EAS 380 Surface Station Plotting Model Key

Last Updated: February 21, 2008

Station Model Examples

Symbolic Station Model

Here is an Example of a Plotted Station Model, using the METAR observation below:

KSTC 311153Z AUTO 35008G14KT 6SM -RA BR FEW004 OVC011 03/02 A2987 RMK AO2 SLP134 P0006 60068 70113 T00280022 10056 20028 56015 8/6// 9/8//

Wind Barb

1. Plot the wind barb first and arrange other elements around the wind barb.
2. Wind direction (degrees; see meteorological wind coordinate system) and speed (to nearest 5 kt) (Also see Table 9 of handout)
   1. Wind feathers are always plotted on the clockwise side of the wind shaft in the Northern Hemisphere.
   2. When the wind is only 5 kt, it is plotted down the shaft a bit and at an angle
      1. Shown as an example on the NWS HPC station model
   3. Calm winds are shown as a second circle around the station circle.
   4. Variable winds (VRB) or missing winds are plotted as missing (M at lower right of station circle).
      1. Include the VRB-group in the comments.
3. Plot 10's digit of wind direction at end of wind shaft
4. If gusts are given, plot "G" followed by the wind gust after 10's digit of wind direction
5. If you are not good at plotting accurate straight lines, use a protractor. A 240 degree wind should look the same throughout the map.
6. Common Student Errors
   1. Not having consistent wind directions.
   2. Plotting the wind barb last on top of other readings.
   3. Plotting wind feathers on wrong side of wind shaft.
   4. Can't tell the difference between a 5 kt feather and a 10 kt feather.
   5. 10's digit plotted sideways or upside down when looking at the map upright.

Sky Cover (N)

1. In METAR code, the only possibilities are CLR, FEW, SCT, BKN, OVC, missing, and obscured (VV group).
   1. See sky cover symbols.
   2. Table 5 shows all the possibilities for sky cover using the synoptic code, which reports sky cover in tenths.
   3. If the station is automated, you must put A01 or A02 as a comment if:
      1. a person could see clouds at 12,000 feet or higher (less than OVC coverage)
      2. visibility is below 7 miles
      3. UP is being reported (weather discriminator can't identify precipitation)
      4. SN is being reported (melted precip. inaccurate)
2. Common Student Errors
   1. Not putting a dot into a clear sky.
   2. Not doing missing or obscured sky correctly.
   3. Not using A01 or A02 comments for an AUTO report when needed.

Temperature (TTT)

1. Temperature (°C) plotted at upper left of station circle.
   1. Plot in whole degrees for stations without a T-group.
   2. Plot with decimal place for stations with a T-group.
   3. Plot negative sign for negative values.
   4. Plot M if temperature is missing.
2. Common Student Errors
   1. Not using the T-group
   2. Plotting "M" rather than a minus sign for negative values.
   3. Plotting leading zero for -10°C<=T<=+10°C
   4. Dropping decimal place for even degrees, i.e. 5.0°C
      1. You must show the decimal place to denote accuracy

Dew Point Temperature (TdTdTd)

1. Dew Point Temperature (°C) plotted at lower left of station circle.
   1. Plot in whole degrees for stations without a T-group.
   2. Plot with decimal place for stations with a T-group.
   3. Plot negative sign for negative values.
   4. Plot M if dew point temperature is missing.
2. Common Student Errors
   1. Not using the T-group
   2. Plotting "M" rather than a minus sign for negative values.
   3. Plotting leading zero for -10°C<=Td<=+10°C
   4. Dropping decimal place for even degrees, i.e. 5.0°C
      1. You must show the decimal place to denote accuracy

Visibility (VV)

1. Visibility (mi) is plotted directly to the left of the station circle.
2. Fractions of a mile can be in either decimal or fraction form.
3. Visibility is plotted to the left of any current weather symbols.
4. Visibility is plotted directly between temperature and dew point if there are no current weather symbols.
5. Plot "<1/4" for stations reporting M1/4 visibility.
6. Variable visibility is plotted as a comment.
7. Plot M if visibility is missing.
8. Common Student Errors
   1. Plotting weather symbols to the left of the visibility

Current Weather (ww)

1. Current weather symbols are plotted to the right of the visibility and directly left of the station circle.
2. The official "100 types of weather" can be found in Table 8, the NWS Aviation Weather Center, and the San Jose State University Weather Symbols description
   1. METAR code does not allow for the 100 types of weather.
3. Frequently used weather symbols can be found at: NWS HPC Weather Symbol decoding
   1. For drizzle, rain, and snow, the number of symbols change from 2 symbols to 4 symbols for light, moderate, and heavy
   2. For fog
      1. Plot the shallow fog symbol (2 lines) if the visibility >= 1 mile
      2. Plot the deep fog symbol (3 lines) if the visibility < 1 mile
   3. BR is shown as "light fog" (2 lines)
   4. UP is plotted as "sleet"
   5. For weather types without change for intensity,
      1. you may use a plus or minus next to the symbol (Example of +/-)
      2. you may just plot the symbol and show the intensity using the rain symbol (Example of two symbols)
   6. Weather symbols not reported in "current weather" section
      1. Precipitation ended during hour and not reported at current time (right square bracket)
         1. Use one rain ended symbol if rain ended, began, and ended again (see above definition).
         2. Put all precip. ended symbols to left of current weather symbols.
      2. Lightning reported without a thunderstorm.
4. Common Student Errors (this is the second most common source of error besides the pressure tendency)
   1. Weather symbols plotted to left of visibility.
   2. Using the wrong number of drizzle, rain, snow symbols or putting them in a wrong orientation.
   3. Using the deep fog symbol when visibility is a mile or more.
   4. Forgetting to look for through comment section for precipitation ended and lightning comments.
      1. Precipitation ended:
         1. Not plotting all precip. ended symbols to left of current weather.
         2. There is no precipitation began symbol (no left square bracket).
      2. Lightning needed when there is no current thunderstorm
   5. Forgetting to plot lightning.
   6. Plotting +TSRA as a severe thunderstorm. (extra bend in lightning part of thunderstorm symbol)
      1. It's a thunderstorm with heavy rain.
   7. Plotting M for station without current weather.
      1. Assume that nothing is going on, except if shown in comments or an A01 station with lowered visibility

Altimeter Setting (PPP)

1. Altimeter setting will be used instead of sea-level pressure in EAS 380, 385, 485, since more stations report altimeter setting and NWS sea-level pressure is not necessarily more accurate.
2. Altimeter setting (converted to mb) is plotted in pressure code to upper right of station circle:
   1. Leading 9 or 10 dropped
   2. Decimal point dropped
   3. M is plotted for stations with missing altimeter setting.
3. Common Student Errors
   1. Decimal point plotted for altimeter setting.
   2. Substituting NWS Sea-Level Pressure for altimeter setting if the station is missing its altimeter setting.

Pressure Tendency (±pppa)

1. Common Student Errors: This is the most frequent source of error in plotted maps. All errors involve not following instructions below:
2. Plotted directly to the right of the station circle as follows:
   1. A sign is plotted (either + or -)
   2. Tendency is plotted
      1. Both units and decimal digits are plotted, even if either is a zero.
         1. 10's digit is only plotted if the net change is at least 10 mb.
      2. No decimal point is plotted.
   3. Tendency symbol is plotted
      1. Use correct symbol as shown in Table 10 or the NWS HPC Station Model Legend for Pressure Change. (Note: The descriptions in this legend are better than those used in Table 10.)

Three-Hour or Six-Hour Melted Precipitation (RRR)

1. Melted Precipitation in the past three hours or the past six hours ("6-group") is plotted at lower right of station circle.
   1. Three-hour precipitation reported at 03Z, 09Z, 15Z, 21Z
   2. Six-hour precipitation reported at 00Z, 06Z, 12Z, 18Z
2. Precipitation is plotted in hundredths of inches, either with or without the decimal point
   1. 60001 would be plotted as 01 or .01
   2. 60010 would be plotted as 10 or .10
   3. 60120 would be plotted as 120 or 1.20
3. 60000 is a trace of precipitation (less than .005 inch) and is plotted as T.
4. Other precipitation groups
   1. "7-group" (24 hr precipitation) is not plotted.
   2. "P-group" (1 hr precipitation) is plotted as a comment.
5. Common Student Errors
   1. Plotting the wrong precipitation group in the precipitation slot.
   2. Plotting the precipitation as a 6-group
   3. Plotting 00 instead of T
   4. Plotting precipitation below comments.

Cloud-Type Groups (CL, CM, CH)

1. Cloud-types are reported in the following formats:
   1. US Military Stations report "8/-group" with symbol for low, middle, and high clouds.
      1. Note: The "9/-group," which notes the sky coverage in eighths for each cloud type, is not plotted, not even as a comment.
   2. Station with humans may report cloud types at each of a cloud height group or in the comments.
   3. Canadian stations often include cloud types in comments. (Scroll to Section 1.3.14 of the University of McGill Canadian METAR Decoding guide)
2. Cloud type symbols are taken from Table 3.
   1. Separate columns for low, middle, and high clouds.
3. Position:
   1. Low cloud symbol is plotted directly below station circle.
   2. Middle and high cloud symbols are plotted directly above station circle with middle under high cloud.
   3. Only one cloud type at each height category (low, middle, height)
4. Common Student Errors:
   1. Ignoring all cloud type comments.
   2. Plotting both "8/-group"and "9/-group" as a comment.

Significant Comments

1. Significant comments are plotted below the station circle as they fit.
2. They are usually plotted in the same code as used in the METAR.
3. Significant comments include:
   1. Type of automated equipment (A01, A02) when it is a factor in the sky cover (see sky cover notes)
   2. One-hour precipitation (P-group)
   3. Precipitation begins and ends groups with times.
   4. Convective cloud groups, e.g., CB, TCU, ACC, ACCAS, LTG, TS, etc., with location relative to the station
      1. Do not plot path of lightning flash, e.g, IC, CG, CC, CA, etc.
   5. Snow increase groups (at least 1" in past hr) and snow depth ("4/-group") when it is snowing.
   6. Pressure rising or falling rapidly group or pressure jump group.
   7. Peak wind gust group with time and direction.
   8. Variable visibility, cloud layer, or wind direction groups.
      1. Also, plot VRB wind as a comment with M at lower right of station model below precipitation (no wind barb can be plotted).
   9. Wind shift comment with time and direction.
4. Do not plot the following as a comment
   1. Anything that belongs in the station model elsewhere.
   2. High and low temperature groups.
   3. NWS Sea-Level Pressure (we are using altimeter setting)
   4. 24-hr precipitation
   5. Non-standard precipitation comments when they are reported every hour, even with no precipitation.
   6. Snow depth when it's not snowing.
   7. Malfunctioning equipment.

Last Updated: February 21, 2008

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