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Federal Highway Administration > Publications > Research > ITS > 508 Captions for FHWA-HRT-04-109 Collaborative Research on Road Weather Observations and Predictions by Universities, State DOTs and National Weather Service Forecast Offices
Publication Number: FHWA-HRT-04-109
Date: September 2004

508 Captions for FHWA-HRT-04-109 Collaborative Research on Road Weather Observations and Predictions by Universities, State DOTs and National Weather Service Forecast Offices

Figure 1. Stations included in the Pennsylvania mesonet. Map.

The figure highlights the State of Pennsylvania by providing a gray background and county borders. The surrounding states have white backgrounds and are only identified with state borders. The figure shows the distribution of observational platforms that together form the Pennsylvania mesonet. A “mesonet” is a network of observation sites that have relatively close spacing between them. In general a mesonet has a denser number of stations than of the National Weather Service airport observing network. Scattered across the State of Pennsylvania are four different kinds of symbols:

  1. PennDOT RWIS is the first in the list and is represented by purple triangles. PennDOT is the Pennsylvania Department of Transportation. RWIS is Road Weather Information System. PennDOT has installed 82 RWIS (road side weather sensors) along major highways in the state. The triangles on the map show the locations of these sensors.
  2. DEP COPAMS is the second in the list and is represented by green pentagons. DEP is the Department of Environmental Protection. COPAMS is the Commonwealth of Pennsylvania Air Monitoring System. There are 47 such sites spread around the state clustered mostly around the urban areas of the southwest and east.
  3. PA FAA is the third line in the list. This is associated with automated airport weather stations that are operated either by the Federal Aviation Administration or the Pennsylvania Aviation Division of PennDOT. These stations are represented by red squares on the map. There are 32 of these sensor scattered across the state with most clustered over the western half and southeast portions.
  4. I-FLOWS is the fourth line in the list. This is associated with the Integrated Flood Observing and Warning System which is operated by the state and is represented by small lavender circles. There are nearly 200 water and rainfall observing platforms scattered pretty evenly across the state.

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Figure 2. Contours of temperature lines. Map.

Figure 2 is a map of the northern mid Atlantic States with state and county borders depicted. Overlaid on the map are lines called “isotherms”. Isotherms are lines that connect equal temperatures. This figure was included to show the kind of detail that a mesonet of densely-spaced weather stations can provide. Each isotherm on the map represents two degrees Fahrenheit and even temperatures are depicted ranging from the coldest readings around freezing in the extreme northeast part of the state to near 40 degrees in the far southwest. Temperature ranges on the map are color-coded for easier interpretation with coldest readings (below 32 degrees in blue) ranging to shades of green as readings approach 40 degrees in the southwest. These temperatures were observed on December 9, 2003 at 3 PM Eastern Standard Time (20 Zulu Time or Greenwich Mean Time).

The bottom of the map hosts a legend, shown as a bar with variant temperatures changing colors as the temperature increases. The bar begins in purple, at the coldest marked at zero degrees Fahrenheit and climbs to dark blue and into light blue marked at thirty-two degrees Fahrenheit. From the light blue the bar changes from to light green, into dark green and then into pale yellow marked as sixty-four degrees Fahrenheit. The yellow then changes to orange and into dark red marked as the hottest at ninety-eight degrees Fahrenheit. To begin, the southwestern corner of the map is colored in a light green, the contour lines reading forty degrees Fahrenheit. The western third of the state is colored in a pale green, the contour lines reading thirty-six degrees Fahrenheit. The majority of the middle and eastern part of the state is colored a pale blue, the contour line arching through the latter section with readings of thirty-four degrees. A small section of the northeastern corner of the map is colored in a darker blue, the contour lines reading thirty-two to thirty degrees Fahrenheit.

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Figure 3. Frequency of observations taken by RWIS network during 1 month. Graph.

This bar graph shows a collection of columns rising across its surface from left to right. The vertical axis of this graph ranges from zero to 1200 and represents Frequency while the horizontal axis represents Stations. The columns all begin on zero of the horizontal axis. The first column rises to the point of 150 on the vertical axis. The remaining sixty-four columns gradually increase in length as time goes by, with one set creating a large plateau at the point of 800 on the vertical axis before jumping considerably to the point of 1200 for the final four columns.

This bar graph indicates that there was no uniformity in the frequency that RWIS platforms were polled to get updated weather information. A frequency value of 800 means that the RWIS reported observations for each hour during the span of one month (that this sample was collected). However, almost two thirds of the graph showed that stations polled less than hourly which made it very difficult for the researchers to do useful things with the data (such as initializing weather models).

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Figure 4. Early example of a quantity assurance report on RWIS data. Clicking on the station designation provides facility details. Diagram/Report.

This figure shows a report containing a brief legend at the top, with a column of specifics running down the left-hand side of the document pertaining to five separate blocks of information to the right, cataloged into hours of the day. The legend at the top of the report hosts three lines of information. The first line reads No Failures and is accompanied by a green block. The second line reads Failures Discovered and is accompanied by a red block. The third and final line reads No Data Available and is accompanied by a black block. The column running down the length of the left-hand side of the document is broken into five separate section each with its respective heading. The first heading reads DOTB2 and is followed by five additional lines reading, DPTEMP, RH, TEMP, WINDDIR, and WINDSPD. The second heading reads DOTB5 and is followed by the same five prompts as the first section. The third heading reads DOTB6 and is followed by the same five prompts as the last, with the exception that this section shows the result of clicking on one of the prompts. A small hand points to the prompt reading DOTB6, when clicked a separate window appears. The window contains five lines of information. The first line, the heading, reads DOTB6 Facility Information. The second line reads City: State Route 62 at President. The third line reads County: VENAGO, while the fourth line reads Nearest Town: President. Finally, the last line reads Vendor: boschung. Resuming to the left-hand side of the document, the fourth heading reads DOTB2, the five prompts following it identical to those already mentioned. The fifth and final heading reads DOTB5 and is followed, once again, by the same five prompts.

The five blocks of information that consume three quarters of the page to the right hand side also contains their respective headings. The first three headings read RWIS status by hour for 20030701, while the last two read RWIS status by hour for 20030702. These five blocks of information in turn are broken up into individual blocks of information, set in rows, representing hours in a day, beginning at 00 hours and ranging to 23 hours. Each separate block of information contains five rows as mentioned above, each row corresponding to its respective prompt, mentioned earlier, i.e., DPTEMP, RH, TEMP, etc.

In the first section of information, all the hour blocks in the combined five rows are colored in green, suggesting that No Failures were present during that time. In the second section, all the hours blocks in the combined five rows are colored green with the exception of the hour blocks marked 17, which are colored black, suggesting that No Data was Available during that time. The third section is impossible to read, as the window of information from the example of clicking on a prompt, covers the majority of the information set it that specific section. In the fourth section, all the hour blocks in the combined rows are colored green with the exception of the hour blocks marked 19, suggestion No Data Available for that time. In the fifth section, all hour blocks in the combined five rows are colored green with the exception of the hour blocks marked 00, suggesting No Data Available for that time.

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Figure 5. Sample metadata page for an RWIS site. Webpage.

This figure shows an example of a webpage found on an RWIS website. The top of the page hosts the heading, highlighted and broken into three sections, reading Pennsylvania State Climatologist in the first section, Pennsylvania Mesonet centered as the second section and main heading, and Metadata in the third section. Beneath the heading are four prompts, which can be clicked to gain various additional information. The four prompts are in white with a light brown block background. The first prompt reads Site description. The second block reads Site Photos. The third block reads Measured Variables. The fourth block reads Data & Facts. Beneath the prompts is an actual site description, with the heading Station DOT337_2. The left-hand side of the page hosts an actual picture of the environmental sensor station, set on a hill and fenced off, with a background of a snowy ground and trees bare of leaves. The remaining three quarters of the page, to the right hand side, hosts additional information on the station, set inn two respective columns. The first column contains descriptive information while its respective second columns contain specifics to that information, resulting in twelve line of information. The first line reads Station Identifier, DOT337_2. The second line reads Station Name, I-80 Exit 192 at Milepost 194. The third line reads Station Organization, Pennsylvania Department of Transportation. The fourth line reads Station Type, RWIS. The fifth line reads Station Manufacturer, SSI. The sixth line reads Station Latitude, 41.046 degrees. The seventh line reads Station Longitude, minus 77.146 degrees. The eighth line reads Station Elevation, 1518 feet. The ninth line reads Distance from Nearest Town Center, 3.5 miles of Carroll. The tenth line reads County, Clinton. The eleventh line reads Climate Division, 7. And finally, the twelfth line reads NWS Forecasting Office and Zone, State College 45.

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Figure 6. Tabletop exercise from roadway managers training session. Maps.

This figure shows a four-panel graphic with each quarter showing a different weather parameter across Pennsylvania at 3 PM (2000 Zulu Time or Greenwich Mean Time) on 6 January. All four of the charts contain the same background; centered on Pennsylvania showing state and county borders.

  • The upper left quadrant contains an isothermal analysis. This is simply a map with contours showing similar temperatures. The temperature bands range from the coldest (in blue) over the western half of the state to shades of green (representing warmer temperatures) across the extreme southeast.
  • The upper right quadrant is a radar image showing areas of precipitation as different colors. The shades of blue along the northern tier of Pennsylvania represent only light precipitation. Much of the state is under moderate precipitation as shown in shades of green. The heaviest precipitation is shown in shades of yellow and orange over Maryland and northern Virginia. In areas where temperatures are above freezing (from the upper left quadrant map), the precipitation is likely falling as rain. In the high terrain of the mountains and in the west, freezing or frozen precipitation is likely.
  • The lower left quadrant shows a streamline analysis. Streamlines are used to show areas of equal wind direction. They also show areas of confluence and divergence which provides forecasters with a picture of general weather patterns or the presence of fronts.
  • The lower right quadrant shows contours of dew points. Dew points are air temperatures that indicate the amount of moisture that is present in the air. When the air temperature falls to meet its dew point, then there is a chance that fog will form. In this chart, the contours of dew point are drawn across the region showing drier air (in shades of purple) covering the eastern third of the state. The remainder of the state contains shades of blue. Those areas in the upper left and lower right quadrants that have the same blue color are likely to have high relative humidities.

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Figure 7. Comparison of RWIS temperatures with ASOS temperatures as a function of RWIS wind speed for 12 stations. Graph.

This figure shows twelve distinctive lines running across a graph. The vertical axis of this graph ranges from negative 6.00 to positive 6.00 and represents RWIS Temperature - ASOS temperature, while the horizontal axis of this graph ranges from zero to 24 and represents RWIS Wind Speed in knots.

The first line, black with hollow diamonds and labeled Ames, begins at the point of positive 3.60 degrees at zero knots and descends across and leaves the graph at the point of negative 0.90 degrees at 24 knots.

The second line, black with hollow squares and labeled Burlington, begins at the point of positive 1.00 degrees at zero knots and descends to the point of negative 2.40 degrees at 17 knots where it then ascends and leaves the graph at the point of negative 1.90 degrees at 24 knots.

The third line, black with black triangles and labeled Cedar Rapids, begins at the point of positive 1.90 degrees at zero knots and abruptly ascends to the point of positive 3.00 degrees at 2 knots where it then descends to the point of positive 1.00 degrees at 20 knots. From this point, the line ascends once more and leaves the graph at the point of positive 3.40 degrees at 24 knots.

The fourth line, black with two dashes and labeled Davenport, begins at the point of positive 3.00 degrees at zero knots and gradually descends across and leaves the graph at the point of positive 0.70 degrees at 24 knots.

The fifth line, black with small black squares and labeled Dubuque, begins at the point of positive 2.00 degrees at zero knots and descends to the point of positive 1.80 degrees at 19 knots where it spikes to positive 2.20 degrees at 20 knots. From this point the line descends to positive 0.70 degrees at 22 knots before ascending and leaving the graph at the point of positive 3.40 degrees at 24 knots.

The sixth line, black with black circles and labeled Iowa City, begins at the point of positive 3.10 degrees at zero knots and descends across and leaves the graph at the point of negative 1.00 degrees at 24 knots.

The seventh line, black with a single dash and labeled Marshall Town, begins at the point of positive 1.20 degrees at zero knots and gradually descends and leaves the graph at the point of negative 0.40 degrees at 24 knots.

The eighth line, black with small black rectangles and labeled Mason City, begins at the point of positive 2.20 degrees at zero knots and gradually descends across and leaves the graph at the point of 0.00 degrees at 24 knots.

The ninth line, black with large black rectangles and labeled Ollumwa, begins at the points of positive 1.70 degrees at zero knots and gradually descends across and leaves the graph at 0.00 degrees at 24 knots.

The tenth line, black with black diamonds and labeled Sioux City, begins at the points of positive 3.00 degrees at zero knots and dramatically descends across and leaves the graph at the point of negative 2.00 degrees at 24 knots.

The eleventh line, black with large black squares and labeled Spencer, begins at the points of positive 3.20 degrees at zero knots and gradually descends across and leaves the graph at the point of negative 0.20 degrees at 24 knots.

Finally, the twelfth line, black with hollow triangles and labeled Waterloo, begins at the point of positive 2.00 degrees at zero knots and where it descends drastically to the point of negative 1.00 degrees at 6 knots. From this point the line nearly plateaus and runs across and leaves the graph at the point of negative 1.00 degrees at 24 knots.

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Figure 8. Comparison of ASOS-RWIS winds speeds as a function of direction for four stations. Diagrams.

This figure shows four spheres with arrows protruding from their sides to illustrate the direction of wind speeds. Each sphere represents an individual station. The main diagram itself hosts a heading that reads ASOS-RWIS wind speeds as function of direction. Below the heading appears a legend. The legend reads, less than negative one (colored light blue), negative one to zero (colored green), zero to 1 (colored white), 1 to 2 (colored yellow), 2 to 3 (colored orange) and greater than 3 (colored red) knots.

The first sphere shown is labeled Ames, with a notation of 2.7 given. The first arrow protruding from the Ames sphere is colored orange at twelve o'clock. The second arrow is orange between one and two o'clock. The third arrow is yellow at three o'clock. The fourth arrow is orange between four and five o'clock, while the fifth arrow is also orange at six o'clock. The sixth arrow is white between seven and eight o'clock and, finally, the seventh arrow is green at nine o'clock.

The second sphere is labeled Iowa City with the notation 2.8 given. The first arrow shown is white and is just left of twelve o'clock. The second arrow is yellow between one and two o'clock. The third arrow is green at three o'clock. The fourth arrow is white between four and five o'clock. The fifth arrow is orange at six o'clock, while the sixth arrow is white between seven and eight o'clock. The seventh arrow is white at nine o'clock. Finally, the eighth arrow is green between ten and eleven o'clock.

The third sphere shown is labeled Ottumwa with the notation 2.7 given. The first two arrows shown are colored orange, the first at twelve o'clock and the second between one and two o'clock. The third arrow is white at three o'clock. The next two arrows are orange, the first between four and five o'clock and the second at six o'clock. The next two arrows are yellow, the first between seven and eight o'clock and the second at nine o'clock. The last arrow is orange and is placed between ten and eleven o'clock.

The fourth and final sphere is labeled Burlington with a notation of 3.7 given. The first arrow shown is yellow and is placed at twelve o'clock. The next two arrows are colored orange, the first between one and two o'clock and the second at three o'clock. The fourth arrow shown is colored red between four and five o'clock. The fifth arrow is colored orange at six o'clock. The sixth arrow is white between seven and eight o'clock. The seventh arrow is orange at nine o'clock. The eighth and final arrow is colored orange between ten and eleven o'clock.

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Figure 9. Comparison of RWIS dewpoint temperatures with ASOS dewpoint temperatures as a function of RWIS wind speed for 12 stations. Graph.

This figure shows twelve distinct lines running across a graph. The vertical axis of this graph ranges from negative 6.00 to positive 6.00 and represents RWIS Dewpoint - ASOS Dewpoint, while the horizontal axis of this graph ranges from zero to 24 and represents RWIS wind speed in knots.

The first line, black with hollow diamonds and labeled Ames, begins with a positive 1.00 dewpoint at zero knots where it gradually descends across the graph to negative 1.00 dewpoint at 21 knots. From this point, the dewpoint drops drastically to negative 3.00 at 22 knots before spiking up and off the graph at 0.00 dewpoint at 24 knots.

The second line, black with hollow squares and labeled Burlington, begins with a 0.00 dewpoint at zero knots where it dramatically descends across the graph to negative 4.70 dewpoint at 17 knots before it spikes to positive 0.50 dewpoint at 20 knots. from this point, the dewpoint then drops to negative 1.50 at 23 knots before ascending off the graph at a dewpoint of positive 1.00 at 24 knots.

The third line, black with black triangles and labeled Cedar Rapids, begins with a positive 2.00 dewpoint at zero knots where it rises gradually to a positive dewpoint of 2.50 at 8 knots before descending across and off the graph to a dewpoint of 0.00 at 24 knots.

The fourth line, black with two dashes and labeled Davenport, begins with a negative 1.00 dewpoint at zero knots and descends very gradually across the graph to a negative dewpoint of 2.00 at 21 knots before ascends ever so slightly and off the graph at a negative dewpoint of 1.90 at 24 knots.

The fifth line, black with small black squares and labeled Dubuque, begins with a positive dewpoint of 2.00 at zero knots where it gradually descends across and leaves the graph at a dewpoint 0.00 at 24 knots.

The sixth line, black with black circles and labeled Iowa City, begins with a positive dewpoint of 2.10 at zero knots where the line gradually descends across and leaves the graph at a negative dewpoint of 1.00 at 24 knots.

The seventh line, black with a single dash and labeled Marshall Town, begins with a negative dewpoint of 1.80 at zero knots where it ascends to a negative dewpoint of 0.80 at 1 knot before descending to a negative dewpoint of 2.00 at 17 knots. From this point the line spikes to a negative dewpoint of 0.50 at 18 knots before dropping to a negative dewpoint of 4.00 at 20 knots and then ascending to a negative dewpoint of 2.00 at 21 knots where the line plateaus until 22 knots. At 22 knots the dewpoint drops again to a negative 3.90 at 23 knots before spiking off the graph at a negative dewpoint of 0.50 at 24 knots.

The eighth line, black with small black rectangles and labeled Mason City, begins with a positive dewpoint of 1.90 at zero knots where it gradually descends across and leaves the graph at a positive dewpoint of 1.00 at 24 knots.

The ninth line, black with large black rectangles and labeled Ottumwa, begins with a positive dewpoint of 4.70 at zero knots where it gradually descends to a positive dewpoint of 3.80 at 19 knots. From this point the the line ascends to a positive dewpoint of 4.70 at 20 knots where it plateaus until 22 knots, then descending to a positive dewpoint of 0.80 at 23 knots before spiking off the graph at a positive dewpoint of 2.00 at 24 knots.

The tenth line, black with black diamonds and labeled Sioux City, begins with a dewpoint of 4.40 at zero knots where it gradually descends across and leaves the graph at a positive dewpoint of 2.40 zt 24 knots.

The eleventh line, black with black squares and labeled Spencer, begins with a positive dewpoint of .080 at zero knots where it then descends across the graph to a negative dewpoint of 1.90 at 18 knots before ascending off the graph at a negative dewpoint of 0.50 at 24 knots.

The twelfth and final line, black with hollow triangles and labeled Waterloo, begins with a positive dewpoint of 2.00 at zero knots where it then descends across the graph to a positive dewpoint of 1.00 at 19 knots. From this point the line then ascends to a positive dewpoint of 1.80 at 21 knots before descending off the graph at a positive dewpoint of 1.00 at 24 knots.

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Figure 10. Locations of the NDOT stations that are available for analysis on the DRI Web site. Map.

This figure shows a map with twenty-three station locations listed and respectively numbered. The numbers, encircled in various colors are placed along specific routes on the map. Number one through 23 respectively, the list of station reads: Carson Valley, Double Springs, Black Springs, Gardnerville, Holbrook Junction, Kingsbury, Tracy Clark, Incline, Diamond Peak, Mount Rose Summit, Bulls Eye, I-580, Washoe Valley, crystal Bay, Sand Harbor, Secret Creek, Spooner Summit, Glenbrook Canyon, Cave Rock, Zephyr Cove, Kahle Drive, Spooner/Carson, and Juntion 50/395. The majority of the stations are located on the map along the routes of 395, 207, and route 25.

Figure 11. A schematic of the DRI-developed real-time forecasting system that assimilates NDOT data in the first 12 hours of the pre-forecasting. Diagram.

This figure shows a diagram containing multiple blocks of information. The diagram itself hosts a heading that reads Structure and applications of the MM5 real-time forecasting system, with a subheading beneath it that reads, DRI - Division Atmospheric Sciences - Atmospheric and Dispersion Modeling Program.

At the center of the diagram appears a rectangular bar. The first quarter of this bar is colored red and is labeled 12 hours. The remaining three quarters of this bar is colored a light blue and is labeled 36 hours, with a block of information directly beneath it, highlighted in blue, which reads MMS Forecast.

To the left of the bar mentioned is the first block of information, which reads Real Time MMS and has arrow pointing to the red section of the bar. Also pointing to the red bar is a block of information above the bar which reads Initial Conditions, NCEP global observation network DRI automatic link. Next to the recently mentioned block is another block of information, having a set of arrows, one pointing to the red section of the bar, the other pointing to the blue section of the bar, which reads Boundary Conditions, ETA model - 48 kilometers, NCEP/NCAR, DRI automatic link.

Directly beneath the red section of the bar is a block of information, which, highlighted in red, reads MMS four-dimensional Data Assimilation. And arrow leads from this block of information to the next directly below it which reads Real Time Access, DRI-WROC. And then, an arrow leads from this last block to one final block of information directly below it, which reads, NDOT Operational Mesonetwork, 23 stations western Nevada.

On the far right hand side of the diagram appears another column of blocks, leading out of the blue section of the bar mentioned, labeled as MMS Output. The first block of information at the very top of this column, highlighted in green reads NDOT Pavement Temperature Model. The next block, highlighted in green reads Applications, air quality, regional transport, wind energy, coupling with oceanic models, coupling with hydrological models, cloud seeding simulations, real-time forecasting (US West Coast). The final block of information, highlighted in green reads NWS, Mesoscale forecasts, National Digital Forecast Database.

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Figure 12. Geographical setup of the real-time MM5 forecasting domains. Map.

The map is a line drawing of the western one-third of the United States. The map is set inside a large square defined as D01 with longitudinal and latitudinal indices along the top, bottom and sides. Across the top and bottom the reference points read left to right as 130 W, 120 W and 110 W, and along both sides the read 40 N and 30 N. A smaller square defined as D02 is drawn on top of the map around a section that has the State of Nevada in the middle. Included in the square around Nevada are the southeastern corner of Oregon and the southern half of Idaho to the north; the western half of Utah and the northwestern corner of Arizona to the east and south; and the majority of the State of California to the south and west.

Figure 13. Time series of wind speeds measured at NDOT Washoe Valley station and simulated with MM5 without FDDA, with run A FDDA options, and with Run C FDDA options. Graph.

This figure shows a one distinct line with various symbols stretching across a graph. The vertical axis of this graph ranges from zero to 20 and represents Wind speed in miles per second, while the horizontal axis of this graph ranges from zero to 25 and represents Hour of simulation. The upper left-hand corner of this graph hosts three lines of information, the first reading Corr. Coeff (Base-Meas):0.4665, the second reading Corr. Coeff (Run A Meas):0.70854, and the third reading Corr. Coeff (Run C-Meas):0.75245. The bottom right hand corner of this graph hosts a legend containing line and symbol specifics. The line is black with a single dash and is labeled Measurements. The first symbol is an X and is labeled Baseline (no FDDA). The second symbol is a circle labeled FDDA Run A and the third symbol is a triangle labeled FDDA Run C.

The line of measurement begins at the point of 12 miles per second on the vertical axis at zero hour on the horizontal axis. The line then descends to 6 miles per second at hour 1 before spiking to 12 miles per second at hour 2. From this point the line drops to 4 miles per second at hour 3 and rises to 8 miles per second at hour 3 and a half before descending to 4 miles per second again at nearly hour five. The line then oscillates between 2 miles per second and 6 miles per second until it reaches hour eleven. From hour eleven the line climbs to 10 miles per second at hour 13 before falling to 6 miles per second at hour 14. The line then oscillates between 6 miles per second and 8 and a half miles per second until hour 16, where the line spikes to 19 miles per second before falling once more 6 miles per second at hour 23. From this point the line climbs again and leaves the graph at 14 miles per second on hour twenty-five.

The first symbol, the X is found at various points along the previous line's trail with a few spots where the symbol has gone astray, at 12 miles per second for hours five and seven, and at 10 miles per second at hours seven and eight. For the remainder of the graph, the baseline nearly follows the measurement's trail.

The second symbol, the circle is found at various points along the previous line's trail though its path begins at a lower rate than the measurement line. The FDDA Run A begins at the point of 6 miles per second on zero hour. The FDDA Run A then runs a wavered line along the point of 4 miles per second until it reaches hour fifteen, at which point the line then begins to ascend and rejoin the initial line of measurement.

The third symbol, the triangle is found at various points along the line of measurement across the entire graph. It rarely strays from the line, and only minimally at best compared to the other symbols on the graph.

Return to Figure 13

Figure 14. Vertical profiles of temperature, dewpoint temperature, and winds measured by radiosonde in Reno, Nevada, on March 31, 2003 at 00 Universal Time (4 p.m. local time)(left panel) and on April 1, 2003 at 12 Universal Time (4 a.m. local time)(right panel)

These charts are called Skew-T LogP Pseudo Adiabatic Charts. They are used to show vertical profiles (hence the title “sounding”) of temperature, dew point and wind as weather balloons ascend. The two charts are from balloon releases at Reno Nevada. The left chart is from 00 Universal Time (4 a.m. Pacific Standard Time) 31 March, 2003. The right chart is from 12 Universal Time (4 a.m. Pacific Standard Time ) 1 April, 2003

The charts have several lines:

  • The horizontal lines are isobars or lines of equal pressure. Pressure is measured in millibars or as indicated on this map hPa which is a hector-Pascal. The pressure at the bottom of the chart is just over 1000 hPa which is standard atmospheric pressure. As one moves up the chart, the horizontal bars get farther apart because the air pressure exponentially reduces. The lowest pressure is 100 hPa at the top of the image.
  • There are red lines that diagonally go from the lower left to the upper right on the chart. These are isotherms or lines of equal temperature in degrees Celsius. The values start out around +20 C at the lower right on the chart and rapidly fall to -180 C at the top left showing how cold the atmosphere can be miles aloft.
  • There are orange and blue lines that curve up from the bottom to the top that are called moist adiabats representing how an air parcel would rise if it were saturated. The dotted blue lines are the dry adiabats that represent how an air parcel rises when it is not saturated.
  • The feather-like “wind barbs” along the right side of the image represent wind speed and direction. Each full barb on the stem represents 10 knots. Each half barb is 5 knots. Each pennant is 50 knots. Winds blow toward the origination point on the stem.

Unfortunately, no one is going to understand what I just wrote unless you have a degree in meteorology. So, here is what the author was trying to show. The left chart shows that the thick red line (which is the trace of temperature) and the thick blue line (which is the trace of dew point) are not very close together. This means that the lowest 20,000 feet of the atmosphere was pretty dry (i.e. no precipitation). Winds at low levels were light out of the southeast becoming westerly at 20-40 knots with height.

In the right chart, the red and blue lines actually meet around 700 hPa (which is about 10,000 feet). This means clouds and possibly rain. The winds are all out of the southwest and are much stronger with many readings in the 50-80 knot range.

These two graphics show the state of the atmosphere before and during a storm in Reno.

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Figure 15. Time series of temperature (upper panel) and wind speed (lower panel) at the Reno, Nevada, station for the period from April 1—2, 2003. Graphs.

This figure shows two separate graphs, each with one distinct line and two distinct symbols.

The first graph shows one distinct line and two separate symbols. The vertical axis of this graph ranges from negative 5 to positive 25 and represents Temperature in degrees Celsius, while the horizontal axis ranges from zero to 50 and represents the Hour of simulation. The upper right hand corner of the graph hosts a brief legend. Within the legend is the one distinct line, labeled Measurements, a red X labeled Baseline (no FDDA), and a blue circle labeled FDDA Run. The line of measurement begins at positive 22 degrees for hour zero. The line then descends to positive 12 degrees for hour 15. From there, the line ascends to positive 25 degrees for hour 20 before falling drastically to zero degrees for hour 38. The line then climbs to positive 7 degrees at hour 48 where it comes to an end. Both the red X and blue circle follow nearly the same suit as one another, beginning at positive 17 degrees for hour zero before falling to positive 6 degrees for hour 15. They then ascend to positive 10 degrees for hour 20 before falling again to negative 3 degrees for hour 37 before ascending once more to positive 3 degrees at hour 50.

The second graph shows one distinct line and two separate symbols. The vertical axis of this graph ranges from zero to positive 15 and represents Wind Speed in miles per second, while the horizontal axis ranges from zero to 50 and represents the Hour of simulation. The upper right hand corner of the graph hosts a brief legend. Within the legend is the one distinct line, labeled Measurements, a red X labeled Baseline (no FDDA), and a blue circle labeled FDDA Run. The line of measurement begins at 10 miles per second for hour zero before dropping to 5 miles per second for hour 5. The line then oscillates between 10 miles per second and 7 miles per second until hour 16 where the line spikes to 15 miles per second for hour 20. The line then rapidly descends to zero miles per second at hour 35 before climbing again to 13 miles per second for hour 40. The line finally drops to 4 miles per second at hour 45 and oscillates a few times before coming to rest at 8 miles per second for hour 48. Both the red X and blue circle follow nearly the same suit as one another, beginning at 8 miles per second for hour zero and then dropping to 4 miles per second at hour 2. They then gradually ascend to 12 miles per second at hour 22 before dropping again to 1 mile per second for hour 38. From this point they ascend once more where they come to an end at 10 miles per second for hour 50.

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Figure 16. A schematic of the NDOT pavement temperature model with its major physical components. Diagram.

This figure shows a drawing of a minivan set on a piece of pavement. The heading to this diagram reads Heat Fluxes of Pavement Energy Budget. In front of the van is a series of arrows some leading into the pavement, some leading out of the pavement and one beneath the pavement. The first arrow leads into the pavement and is labeled short wave radiation. The next three arrows lead into and out of the pavement. The first is labeled long wave radiation. The second is labeled sensible heat. The next is labeled latent heat. The next arrow is shown leading into the pavement and is labeled traffic. Finally, the arrow beneath the pavement is leading both into it and out of it and is labeled conduction from ground.

Figure 17. Computer screen with a menu for predicted meteorological parameters to be input for the pavement temperature model run.

This figure shows a copy of a computer screen with various readouts. The title at the top of the menu bar of the screen reads Shortcut to F.bat. The page heading reads Model Input - VTMI Icebreak Model. The page hosts a variety of information. The first line near the top of the page reads Site MP0.15 Incline, Start Date 31 -Oct - 02, Time 0400. The next line of information reads Surface temp 17.0, Depth temp 14.1, F1 SWAP, F2 LOAD. F10 SAVE, Realistic Update, F5 Abrt. The next grouping of information is broken into columns. The first column reads, at 1200, air temp 9.8, dew point 7.4, wind speed (kts) 11, cloud cover 8, cloud type LC, and precipitation 0. The next column reads, at 1500, air temp 11.0, dew point 9.0, wind speed (kts) 2, cloud cover 8, cloud type LC, and precipitation LR. The third column reads, at 1800, air temp 9.2, dew point 7.2, wind speed (kts) 2, cloud cover 8, cloud type LC, and precipitation MR. The next column reads, at 2100, air temp 6.6, dew point 4.6, wind speed (kts) 4, cloud cover 2, cloud type LC, and precipitation MR. The next column reads, at 0000, air temp 3.4, dew point 1.4, wind speed (kts) 4, cloud cover 8, cloud type LC, and precipitation MR. The sixth column reads, at 0300, air temp 1.2, dew point 0.2, wind speed (kts) 4, cloud cover 8, cloud type LC, and precipitation MR. The next column reads, at 0600, air speed 3.0, dew temp 2.0, wind speed (kts) 4, cloud cover 8, clout type LC, precipitation MR. The next column reads, at 0900, air temp 5.4, dew point 2.4, wind speed (kts) 4, cloud cover 8, cloud type LC, and precipitation MR. The final column reads, at 1200, air temp 11.5, dew point 7.5, wind speed (kts) 6, cloud cover 8, cloud type LC, and precipitation MR.

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Figure 18. Computer menu screen with a list of stations for which the pavement temperature forecast can be obtained.

This figure shows a copy of a computer screen with various readouts. The title at the top of the menu bar reads Shortcut to F.bat. The heading at the top of the page reads Model Control. The page is broken into twelve lines of information, each with a respective category. The six categories in order reads Site, Name, Source Copy, Input, Model, and Text. Neither of the twelve lines show any data for the categories of Source Copy or Text. The first line reads D3 J4, Pinto Summit, with no data for Input or Model. The second line reads D3 J5, Antelope Summit, with no data for Input or Model. The third line reads D3 J6, Robinson Summit, with no data for Input or Model. The next line reads NV 01, MP0.15 Incline, 18:45, 18:45. The next line reads NV 02, MP5 Diamond Peak, 18:45, 18:45. The list of twelve lines continues in this manner. The very bottom of the page hosts several prompts highlighted in green block which read, F1 NEW, F2 EDIT, F3 LOAD, F4 COPY, F5 RUN, F6 VIEW, F7 PRNT, F8 ALL, F9 DSEL, and F10 QUIT.

Figure 19. A time series of the forecaster pavement temperature at the Incline Village station for the test case for the period of 3 a.m. on October 31, 2002, to 3 a.m. on November 1, 2002. Graph.

This figure shows a copy of a computer screen, which in turn shows a graph, and several lines of various information. The top of the page hosts several lines of data. The first line reads Realis, Wet, L. Frost, L. Dew. The second reads Pessim, Wet Prec, H. Frost, H. Dew. The third line reads Actuals, Dry, Ice, Snow. Two other lines of data are given following the latter three. The first reads Realistic map: Damped. The second reads Pessimistic map: Unknown.

The actual graph on the page shows one distinct line. The vertical axis ranges from 2 to 18, while the horizontal axis ranges from 03 through 00 to 03. The line begins at 17 on the vertical axis and 03 on the horizontal axis where it descends gradually to the point of 12 on the vertical axis and 13 on the horizontal axis. From this point the line then slopes downward to the point of 4 on the vertical axis and 18 on the horizontal axis where it then slopes back up and ends at 7 on the vertical axis and 02 on the horizontal axis.

The bottom of the page hosts several prompts highlighted in green blocks which reads, F1 PREV, F2 NEXT, F3, F4 Real, F5 PESS, F6, F7 ISSU, F8 NEW, F9 EDIT, and F10 QUIT.

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Figure 20. Time series of the pavement temperature predicted by the NDOT IceCast Pavement Model for various changes in meteorological input parameters with respect to the baseline run. Graph.

This figure shows a cluster of distinct lines on a graph. The vertical axis of this graph ranges from negative 12 to positive 13 and represents Temperature in degrees Celsius, while the horizontal axis ranges from zero to 24 and represents hours after the start of the model. Twenty-two lines represent to following: Temperature plus 2, Temperature plus 1. Temperature minus 1, Temperature minus 2 Dewpoint plus 2, Dewpoint plus 1, Dewpoint minus 1, Dewpoint minus 2, Wind Speed plus 2, Wind Speed plus 1, Wind Speed minus 1, Wind Speed minus 2, Total Cloud Cover plus 4, Total Cloud Cover plus 8, Precipitation plus 1, Precipitation plus 2, Surface Temperature plus 1, Surface Temperature plus 2, Temperature minus 1, Surface Temperature minus 2, and Depth Temperature plus 1.

The bulk of the lines follow nearly the same suit, all beginning between the range of 1 to 6 degrees positive for the first hour and with all but two lines rising to near 6 degrees positive at the second hour . Total Cloud Cover plus 4 and Total Cloud Cover plus 8 descend from the starting point and after the second hour, all other lines descend. The descent is sharp from the 2nd to the 5th hour when all lines are at the minus 2 degrees point on the graph. The lines fall more gradually after that. The lowest point for most lines occur around the 19th hour. Temperatures range from minus 7 to minus 12 degrees at that time. After a slow ascent, at the 21st hour, all lines rise steeply over the 22nd and 24th hours. There is a cluster around 12 to 13 degrees, another cluster around 6 to 7 degrees, and a third cluster around minus 2 degrees. The lines reach the end of the chart at this point.

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Figure 21. Change of the predicted minimum pavement temperature as a function of changing meteorological inputs by step units. Graph.

This figure shows a graph with twenty-four columns either rising above the point of zero on the vertical axis or falling below the point of zero. The vertical axis of this graph ranges from negative 2 to positive four with all twenty-four columns beginning at the point of zero. The first column titled Temperature plus 2 rises to positive 1.3. The second column titled Temperature plus 1 rises to positive 0.75. The third column titled Temperature minus 1 descends to negative 1.65. The fourth column titled Temperature minus 2 descends to negative 1.5. The fifth column titled Dewpoint plus 2 rises to positive 0.15. The sixth column titled Dewpoint plus 1 rises to positive 0.12. The seventh column titled Dewpoint minus 1 descends to negative 0.09. The eighth column titled Dewpoint minus 2 descends to negative 0.12. The ninth column titled Wind Speed plus 2 descends to negative 0.05. The tenth column titled Wind Speed plus 1 descends to negative 0.025. The eleventh column titled Wind Speed minus 1 rises to positive 0.025. The twelfth column titled Wind Speed minus 2 stays at zero. The thirteenth column titled Total Cloud Cover plus 4 rises to positive 1.9. The fourteenth column titled Total Cloud Cover plus 8 rises to positive 3.25. The fifteenth column titled Precipitation plus 1 rises to positive 2. The sixteenth column titled Precipitation plus 2 rises to positive 1.98. The seventeenth column titled Surface Temperature plus 1 rises to positive 0.25. The eighteenth column titled Surface Temperature plus 2 rises to positive 0.05. The nineteenth column titled Surface Temperature minus 1 descends to negative 0.025. The twentieth column titled Surface Temperature minus 2 descends to negative 0.05. The twenty-first column titled Depth Temperature plus 1 rises to positive 0.25. The twenty-second column titled Depth Temperature plus 2 rises to positive 0.35. The twenty-third column titled Depth Temperature minus 1 descends to negative 0.15. Finally, the twenty-fourth column titled Depth Temperature minus 2 descends to negative 0.25.

Return to Figure 21

Figure 22. NYSDOT RWIS stations for which manually downloaded data have been analyzed. Map.

This figure shows a satellite photo of the Hudson Valley of New York with various spots marked, representing the Hudson Valley Ambient Meteorological Study airports and State Department of Transportation stations. Three Department of Transportation stations in particular are pointed out by red lines drawn outside the map with their names indicated. The three are in the center of the map and are located near each other on a north/south line. The northern most one is called rt29, the middle one is called rt5, and the southern most one is called i88

Figure 23. Panoramic views of three of the weather stations studied. Photographs.

This figure shows three photos of weather stations.

The first station, labeled as i88, can be seen resting at the top of a small hill. The white tower rises level to the treetop line found behind the structure. A few hundred yards to the left of the tower sits a bridge, a guardrail stretching from the bridge, in front of the station and out of frame to the right hand side of the photograph. The photo was taken at some distance hindering any actual detail for description.

The second station, labeled Rt. 5 shows the white tower rising out of frame, the structure fenced in and sitting on a large expanse of grass. The quality of the photograph hinders any additional detail concerning the structure.

The third station, labeled rt29 shows the bottom half of the tower fenced in securely. The structure sits in an expanse of grass a bit overgrown with foliage, with a road and a vehicle parked somewhat at a distance in the background.

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Figure 24. Wind roses and transmission factors for surface weather stations. Diagrams.

A wind rose is a climatological tool that is used to describe how often the winds blow from a particular direction and at what speed. As an example, at Washington’s National Airport, the winds generally blow from either the south or the north because it is on the Potomac River. During the winter, with frequent frontal passes, the winds typically blow out of the northwest at high speeds. So, if we were to create a wind rose for National Airport, we would have a circle representing the compass of all possible directions. We would have thick black lines about half the radius point to the north and south. We would have a longer thick line pointing to the northwest. By looking at this rose, it would be easy to see the distribution of north, south and northwest winds. On the roses in figure 24, there are light gray outlines in each rose. That shows the distribution of general wind speed and direction around the whole compass. So, at National, even though most of the time the winds blow from the north, south or northwest, there are occasions when the wind blows from other directions. These occasions are represented by the light gray lines.

With that background, figure 24 has 9 wind roses. Each rose represents one weather station. In many cases, the winds tend to blow from specific directions. For example, at station 1 (top left), it is pretty clear by looking at the light gray line that most of the winds blow either from the northwest or the southeast. The most significant winds blow from the west, northwest and north as shown by the thick black lines. Strong winds from the southwest and north northeast are pretty rare. These kinds of images can show if there are terrain or structure blockage that affect the accuracy of the weather sensors.

Return to Figure 24

Figure 25. Locations of Meso West stations (plus symbols), RWIS station (Green triangles), and Union Pacific Railroad stations (yellow diamonds). Map.

This figure shows a map of the Western Hemisphere of the United States with symbols placed at specifics points along its face. The Meso West stations, represented by plus symbols, saturate the areas of California, Oregon and Washington. They also have a strong appearance in the states of Indiana, Montana, Utah, and Colorado, with sparser showings in Nevada, Arizona, Wyoming and New Mexico.

The RWIS stations, represented by green triangles appear to have a heavy showing in Washington, Montana, Colorado and Utah, with condensed appearances at the northern border of California and Nevada, the northern border of California and Oregon, and the southern border of Indiana and Utah. The stations are also sparsely dispersed through the state of Nevada.

The Pacific Railroad stations, represented by yellow diamonds, forms a crude Y, with its stem beginning in the state of Nebraska and running through the state of Wyoming, splitting at the borders of Wyoming and Indiana. The split carries one line of the Y through Indiana and into Oregon, ending near the border of Oregon and Washington. The other half of the split carries the line through Colorado and the southern portion of Nevada before coming to an end in southern California.

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Figure 26. Summary of current weather and road state in Utah available in Meso west. Webpage.

This figure shows a copy of a webpage containing an amassed amount of information. The heading at the top of this page reads Current Conditions along Transportation Corridors: December 17, 11:02 MST. The left-hand side of this page hosts several prompts in one column. The column of prompts reads Summaries, Images, Forecasts, and Other Sites. The remainder of the page and its information is then organized in several columns. The first column presents the Station Location with Station Name. The names of the stations in question are then listed beneath this heading, grouped as the stations in each various location. The next column is labeled ID and lists the respective station ID's, highlighted in blue and underlined. The next column is labeled Time, with the respective times the conditions were taken inserted here for each station. The next three columns represent temperature variants. The first, being Air Temperature in degrees Fahrenheit. The second, being Road Temperature in degrees Fahrenheit. And the third being Freezing Temperature in degrees Fahrenheit. The next column is labeled Road State, and hosts the road conditions, mostly wet or dry. The next column is labeled Speed in knots, and refers to wind speed at the time the conditions were recorded. The next column is labeled Direction, referring to wind direction. Finally, the last column is labeled RH in percentage or the relative humidity which is an estimation of the amount of moisture that is in the air. The higher the humidity, the closer the air is to saturation. Often times, the air is saturated when it rains or if there is fog. The air can be saturated (called 100 percent humidity) during the early morning around sunrise. As the sun heats the air (and the amount of moisture stays the same) the “relative” humidity decreases. RH is reported in percent as a ratio of the amount of dry air to saturated air.

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United States Department of Transportation - Federal Highway Administration