Nighttime Public Weather Outlooks to be Issued by The Storm Prediction Center

Cool-season nighttime tornadoes pose a particular challenge to forecasters, and are also a substantial threat to the public.  In the wake of the Super Tuesday Outbreak of February 2008, it was found that many people did not expect tornadoes, especially in February, and especially at night. Late night tornado events also pose a significant challenge to public safety officials when alerting the public to the impending threat can be extremely difficult after people have gone to bed. While it is recognized that the bulk of these events will remain difficult to forecast and highly uncertain, the SPC is in the best position to offer guidance and meteorological support ahead of these "high impact, low probability" events. To that end, this is a initial attempt to improve our commitment to saving lives and protecting property.

Beginning December 1, 2009 and lasting through March 31, 2010, the Storm Prediction Center will issue Public Severe Weather Outlooks (PWO) following the issuance of a 2000 UTC and/or 0100 UTC Day 1 Outlook (SWODY1) when a 10 percent probability of significant tornadoes (hatched area) is forecast after dark anywhere in the CONUS.  These PWOs will be specifically worded to address the threat of nighttime tornadoes and issued even if an earlier PWO was issued for significant severe weather during daylight hours.

Here is an example of what this product would look like:

PUBLIC SEVERE WEATHER OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0600 PM CST WED JAN 06 2010

...SEVERE THUNDERSTORMS EXPECTED OVER PARTS OF XXXX OVERNIGHT...

THE NWS STORM PREDICTION CENTER IN NORMAN OK IS FORECASTING THE
POSSIBLE DEVELOPMENT OF TORNADOES OVER PARTS OF XXXX OVERNIGHT.

CONDITIONS ARE EXPECTED TO SUPPORT THE POTENTIAL FOR A FEW STRONG AND
POSSIBLY LONG-LIVED TORNADOES.

WHILE OVERALL SEVERE THUNDERSTORM COVERAGE IS NOT EXPECTED TO BE
WIDESPREAD...THE POTENTIAL FOR A SIGNIFICANT TORNADO AFTER DARK 
WARRANTS HEIGHTENED SAFETY PRECAUTIONS.

TORNADOES DURING THE OVERNIGHT HOURS AT THIS TIME OF YEAR CAN BE
PARTICULARLY DANGEROUS BECAUSE THEY ARE USUALLY FAST-MOVING
AND OBSCURED BY RAIN AND DARKNESS.

THE AREAS MOST LIKELY TO EXPERIENCE THIS ACTIVITY INCLUDE

       XXXX AND XXXX

STATE AND LOCAL EMERGENCY MANAGERS ARE MONITORING THIS DEVELOPING
SITUATION. THOSE IN THE THREATENED AREA ARE URGED TO REVIEW SEVERE
WEATHER SAFETY RULES AND TO LISTEN TO RADIO...TELEVISION...AND NOAA
WEATHER RADIO FOR POSSIBLE WATCHES...WARNINGS...AND STATEMENTS
TONIGHT.

..CARBIN.. 01/06/2009

$$


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