METAR and Station plots

Meteorological Analysis October 4, 2010 By Tom Collow KSMQ K = identifier for stations in the continental United States For stations located in Alaska and Hawaii the first letter would be “P.” SMQ = station abbreviation SMQ = Somerset, NJ

For a detailed list of station abbreviations go to http://www.nws.noaa.gov/tg/siteloc.shtml 031953Z AUTO

03 = Calendar Date 1953Z = 19:53 Z or UTC UTC = EST + 5 hours, or UTC = EDT + 4 hours So 19:53 Z = 14:53 EST = 15:53 EDT AUTO = automated station could also have COR which means correction to previous report. 02009G16KT

020 = direction from 20° (NNE) 09 = wind speed of 9 knots G16KT = wind gusts of 16 knots

If you see “00000” here, it signifies a calm wind. VRB is used to signify a varying . (ex. VRB02KT) Your Turn • KEWR 072305Z COR 22504KTS

• Where? Newark, NJ

• When? 7th at 23:05 UTC or 19:05 EDT

• Type? Correction to previous report • Wind direction and speed?

from 225° or SW at 4 knots 3/4SM RA 3/4SM = of 3/4 of a statue mile RA = current term RA = moderate see sakai for complete list of terms

Note: RA alone denotes moderate rain -RA would mean light rain +RA would mean heavy rain

Observations can be combined, for example, +TSRA = with heavy rain OVC010

Represents cover in hundreds of feet In the example above, it is overcast at 1000 feet 1 octa = 1/8 of sky SKC = Sky Clear CLR = Sky Clear below 12,000 feet FEW = 1–2 octas covered SCT = scattered = 3–4 octas covered BKN = broken = 5–7 octas covered OVC = overcast = 8 octas covered

Ex. BKN021 FEW120 = Broken at 2100 feet and few clouds at 12000 feet (sometimes more than 1 cloud layer is reported) 17/14 A2992

17/14 = of 17°C Dewpoint of 14°C

An “M” before the numbers denotes a “minus” sign

Ex. 05/M12 = temperature of 5°C and a dewpoint of -12°C

A2992 = altimeter reading of 29.92 in. Hg

Altimeter setting = dependent on only station pressure and elevation, not temperature. Remarks (RMK) SLP = Sea Level Pressure Details on all of the different remarks are available on sakai, I will only have time for the most important ones SLP851 = sea level pressure of 985.1 mb SLP134 = sea level pressure of 1013.4 mb Add either a 9 or 10 to the front of the number and a decimal point after the second number. General rule: add 9 if number is between 500 and 999 add 10 if number is between 000 and 499 Except for extreme circumstances (hurricanes), the pressure range is between 950 mb and 1050 mb.

Use the three digit number in the station plot The 1 and 2 Groups Six Hour Max/Min temperature • 10ttt • Gives maximum temperature over the last 6 hours with enough precision to be converted to the nearest whole degree Fahrenheit. • ttt = temperature = tt.t degrees Celsius • A leading digit of 2 signifies the 6 hour minimum temperature • If the temperature is negative, the “0” term will be replaced by a “1.” • Ex. 10047 21011 • 6 hour max temperature = 4.7°C • 6 hour min temperature = -1.1°C The 5 Group: 3 hour pressure tendency 5XNNN X = code number 1 through 8 (see chart below) nnn = pressure tendency in tenths of millibars Whether pressure is rising or falling depends on X Ex. 53014

Pressure is 1.4 mb higher than it was 3 hours ago.

Ex. 56018

Pressure is 1.8 mb lower than it was 3 hours ago. Temperature Conversion Term: T0ttt0ddd • Gives Celsius temperature and dewpoint in enough precision to be converted to the nearest whole degree Fahrenheit. • ttt = temperature (tt.t), ddd = dewpoint (dd.d) • Example T01720139 • Temperature = 17.2°C = 63°F • Dewpoint = 13.9°C = 57°F • If the temperature is negative, the “0” term will be replaced by a “1.” • Use these in the station plot The P,6, and 7 Groups :

Pnnnn nnnn = precipitation in the last hour in hundredths of inches Ex. P0023 = 0.23” of precipitation in the last hour Instead of P, use 6 for total precipitation over the last 6 hours and 7 for total precipitation over the last 24 hours Ex. 60082 = 0.82” of precipitation in the last 6 hours Ex. 70145 = 1.45” of precipitation in the last 24 hours Wind Speed

Wind Direction ° Temperature, F Sea level Pressure, mb

Current Weather Pressure Tendency

Dewpoint , °F