How to Read a METAR Report, Page 5 of 10

Good job! Here are the table-decoded observations from Charlotte again:

METARDECODE> clt 7z-18z

STN  TIME VIS PRESS  ALTMR TMP DEW DIR SPD GST WEATHER          CLOUDS                REMARKS
==== ==== === ====== ===== === === === === === ================ ===================== =======
KCLT 0650 0.5 1013.3 29.94  21  20 060   3 -99 FG               BKN001 OVC005         SLP133 T02100196=
KCLT 0719 0.7 -999.9 29.94  21  21 000   0 -99 BR               SCT001 BKN005 OVC022
KCLT 0750 0.7 1013.3 29.94  22  21 060   4 -99 BR               OVC006                SLP133 98059 T02160210=
KCLT 0820 1.5 -999.9 29.94  22  21 080   3 -99 BR               BKN008 OVC014
KCLT 0850 1.5 1013.3 29.94  22  21 080   3 -99 BR               OVC005                SLP133 8/6// T02190206 56003=
KCLT 0950 1.5 1013.3 29.94  22  20 080   4 -99 -RA BR           BKN008 OVC020         RAB45 SLP133 T02170201=
KCLT 1025 1.5 -999.9 29.95  22  20 160   4 -99 BR               FEW005 OVC010         SFC VIS 3=
KCLT 1030 1.5 -999.9 29.96  22  20 240  12 -99 TS BR            FEW005 OVC010         OCNL LTGIC W TSB30 TS W MOV N=
KCLT 1050 1.5 1014.8 29.98  19  19 250  10 -99 +TSRA BR         SCT005 OVC010         FRQ LTGICCG TSB30 TS OHD MOV NE PRESRR SLP148
T01920189=
KCLT 1050 1.5 1014.8 29.98  19  19 250  10 -99 +TSRA BR         SCT005 OVC010         FRQ LTGICCG TSB30 TS OHD MOV NE SHRAB35 PRESRR
 SLP148 T01920189=
KCLT 1130 2.5 -999.9 30.00  19  19 320  11 -99 TS +SHRA SHRA BR SCT005 SCT010 OVC030  OCNL LTGICCG TS N MOV NE=
KCLT 1150   4 1015.2 29.99  19  19 330   9 -99 TS +SHRA SHRA BR FEW005 SCT010 OVC045  OCNL LTGICCG TS N MOV NE SLP152 60072 70072 8/
9// T01850185 10220 20185 53017 K=
KCLT 1150   4 1015.2 29.99  19  19 330   9 -99 -TSRA BR         FEW005 SCT010 OVC045  OCNL LTGICCG TS N MOV NE SLP152 60072 70072 8/ 
9// T01850185 10220 20185 53017=
KCLT 1216   5 -999.9 29.99  18  18 030   5 -99 -SHRA            FEW005 OVC040
KCLT 1216   5 -999.9 29.99  18  18 030   5 -99 -SHRA            FEW005 OVC040         TSE15 MOV E=
KCLT 1250   6 1015.2 29.99  19  18 010   6 -99 -SHRA            FEW005 BKN045 OVC095  TSE15 MOV E SLP152 T01850184=
KCLT 1351  15 1015.2 30.00  19  18 050   5 -99                  BKN045 OVC100         SHRAE30 SLP152 T01940181=
KCLT 1450  15 1014.8 29.98  22  19 040   5 -99                  BKN100                SLP148 60004 8/070 T02200194 58003=
KCLT 1651  15 1013.9 29.96  27  19 080   4 -99                  FEW020 FEW100         SLP139 T02650192=
KCLT 1750  20 1013.4 29.95  28  20 140   4 -99                  SCT030 SCT100 BKN250  SLP134 60004 8/171 T02780199 10278 20183 57012
=

To use these observations for weather forecasting, particularly in the National Collegiate Weather Forecasting Contest, you need to be able to read some of the codes in the remarks. Here, I will discuss one-hour precipitation, three- and six-hour precipitation, exact temperatures, and six-hour maximum and minimum temperatures.

The one-hour precipitation is not reported by Charlotte. If it were, you would see a five-character group starting with a P, such as P0005. The numbers indicate the amount of precipitation, in hundredths of inches, during the current hour.

The six-hour precipitation is reported every six hours, at 0000 GMT, 0600 GMT, 1200 GMT, and 1800 GMT. Look at the 1200 UTC observation (the one taken at 1150 UTC). See the five-character group starting with a 6, highlighted in red? That's the amount of rain (or liquid equivalent of snow), in hundredths of inches, which has fallen during the preceding six hours. To keep a running total of the amount of rain, just add up the successive six-hour totals. In between, every three hours, the 6 group is the intermediate three-hour total.

In our example, at 1200 GMT, CLT reported 60072, or 0.72 inches of rain in six hours. Did they get any more? At 1500 GMT, they reported 60004, for another 0.04 inches of rain in the three hours between 1200 GMT and 1500 GMT. At 1800 GMT, they also reported 60004. Was that an additional 0.04 inches? No. The 1800 GMT observation covers the period 1200 GMT to 1800 GMT, and therefore includes the 0.04 inches reported at 1500 GMT.

Temperatures and dew points are reported to the nearest tenth of a degree Celsius in the nine-digit T group. At 1150 UTC, you will find T01850185, highlighted in purple. This means that the temperature and dew point are both 18.5 C. In the main part of the report, they were only reported to the nearest whole degree, or 19 C. The difference amounts to almost a full degree Fahrenheit.

Maximum and minimum temperatures are reported every six hours. The 1 group contains the max, in tenths of a degree Celsius, and the 2 group contains the min. To get, say, the maximum temperature for a longer period, take the highest max from any given six-hour period within that interval. So what was the maximum temperature at CLT between 0600 UTC and 1800 UTC? At 1200 UTC they reported 10220 (shown in brown), for a high of 22.0 C. At 1800 UTC they reported 10278, for a high of 27.8 C. So the overall high was 27.8. You'll note that the current (1800 UTC) temperature is also 27.8 C, so I bet the temperature is still going up.

Questions or Comments

Technical: E-mail John Fulton < jdfult@nimbus.met.tamu.edu >
Scientific: E-mail Dr. John Nielsen-Gammon. < nielsen@ariel.met.tamu.edu >