Office Forecast and Warning Statistics - NOAA's National Weather Service Forecast Office

Office Forecast and Warning Statistics for NWS Charleston

On this page, you will find office forecast and warning statistics for some of the programs at NOAA National Weather Service Charleston, WV. The statistics are separated by warning or forecast type and are presented in tables, with specific entries defined.

A severe thunderstorm is defined as a thunderstorm which produces a tornado, hail ¾” or greater, or winds of 58 mph or greater.

NOE – Number Of Events – the number of storms which produced severe weather

POD – Probability Of Detection – Percent of storms which produced severe weather for which a warning was issued. Higher is better.

FAR – False Alarm Ratio – Percent of warnings issued for which a severe weather report was not received. Lower is better.

LT – Lead Time – The average number of minutes between the time a severe thunderstorm warning was issued and the severe weather was observed. Higher is better.

2010 GOAL – Annual goal for 2010.

	12 month period ending 6/30/2009	2010 GOAL	2008	2007
NOE	272	--	415	218
POD	89%	86%	84%	92%
FAR	36%	33%	28%	36%
LT	22	20	19	17

A Flash Flood is defined as flooding from very quick rises of streams and creeks that causes an imminent threat to life and property

NOE – Number Of Events – the number of times flash flooding was reported from a storm system.

POD – Probability Of Detection – Percent of times flash flooding was reported from a storm system for which a warning was issued. Higher is better.

FAR – False Alarm Ratio – Percent of warnings issued for which a flash flood report was not received. Lower is better.

LT – Lead Time – The average number of minutes between the time a flash flood warning was issued and the flash flooding was observed. Higher is better.

2010 GOAL – Annual goal for 2010.

	12 month period ending 6/30/2009	2010 GOAL	2008	2007
NOE	12	--	10	7
POD	83%	90%	71%	100%
FAR	61%	--	9%	46%
LT	32	49	33	52

A Winter Storm is considered worthy of a warning if snow accumulates at a rate of 5 inches in a 12 hour period or 6 inches in a 24 hour period.

Also, a Winter Storm is considered worthy of a warning in mixed weather events where significant accumulations of snow, sleet, and/or freezing rain are expected. Such events typically cause potentially life threatening travel conditions and widespread disruptions to commerce.

NOE – Number Of Events – the number of times winter storm criteria was reported in a county.

POD – Probability Of Detection – Percent of times winter weather worthy of a warning was reported from a storm system for which a warning was issued. Higher is better.

FAR – False Alarm Ratio – Percent of warnings issued for which winter weather worthy of a warning was not received. Lower is better.

LT – Lead Time – The average number of hours between the time a winter storm warning was issued and the winter weather reached warning levels. Higher is better.

2010 GOAL - Annual goal for 2010.

	12 month period ending 6/30/2009	2010 GOAL	Winter 08-09	Winter 07-08
NOE	67	--	67	26
POD	97%	90%	97%	100%
FAR	16%	--	16%	32%
LT	32	15	24	25

Rainfall forecast quality is defined using the Probability Of Precipitation (POP) forecast for the first "period" of a forecast. That is, we use the POP forecast for the "today" portion of the morning forecast issuance, or the POP forecast for the "tonight" portion of the afternoon forecast issuance.

PFC – Percent of Forecasts Correct – the percent of the time the POP forecasts were correct. Higher is better.

PI – Percent of Improvement - the percent improvement the POP forecast made to the computer model forecast.

TP – Time Period – Time period for which the statistics are valid.

TP	12 month period ending 6/30/2009	2008	2007
PFC	88%	88%	86%
PI	14%	15%	13%

Temperature forecast quality is defined using the temperature forecast for the first "period" of a forecast. That is, we use the maximum temperature for the "today" portion of the morning forecast issuance, or the minimum temperature for the "tonight" portion of the afternoon forecast issuance. The quality is based on the frequency the maximum or minimum temperature is within 3 degrees of the forecast and within 5 degrees of the forecast.

TFQ3 – Temperature Forecast Quality – the percentage of time the forecast is within 3 degrees of the observed maximum or minimum observed temperature. Higher is better.

TFQ5 – Temperature Forecast Quality – the percentage of time the forecast is within 5 degrees of the observed maximum or minimum observed temperature. Higher is better.

TP – Time Period – Time period for which the statistics are valid.

TP	12 month period ending 6/30/2009	2008	2007
TFQ3	74%	74%	75%
TFQ5	91%	90%	91%

Aviation statistics are based on forecasts/occurrence of IFR or worse flight conditions. IFR is defined as the presence of a ceiling of less than 1000 feet, or of visibility of less than 3 miles. Statistics are calculated for scheduled TAF issuances only (00Z, 06Z, 12Z, and 18Z) and only look at the first 6 hours of the forecast. Observations are verified against the TAF conditions, from either the FM or TEMPO groups, judged to be of most significance to aircraft operations.

POD - Percent of the time IFR or worse flight conditions were observed when the TAF was forecasting such conditions. Higher is better.

FAR - Percent of the time the TAF was forecasting IFR or worse conditions, when no such conditions were observed. Lower is better.

TP – Time Period – Time period for which the statistics are valid.

2010 GOAL - Annual goal for 2010.

TP	12 month period ending 9/30/2009	2010 GOAL	2008	2007
POD	59%	65%	57%	53%
FAR	41%	42%	41%	40%