(All days are valid from 12 UTC - 12 UTC the following day)
Note: A severe weather area depicted in the Day 4-8 period indicates a 30% or higher probability for severe thunderstorms within 25 miles of any point.
PREDICTABILITY TOO LOW is used to indicate severe storms may be possible based on some model scenarios. However, the location or occurrence of severe storms are in doubt due to: 1) large differences in the deterministic model solutions, 2) large spread in the ensemble guidance, and/or 3) minimal run-to-run continuity.
POTENTIAL TOO LOW means the threat for a regional area of organized severe storms appears highly unlikely during the entire period (e.g. less than a 30% probability for a regional severe storm area across the CONUS through the entire Day 4-8 period).
Forecast Discussion
ZCZC SPCSWOD48 ALL
ACUS48 KWNS 150957
SPC AC 150957
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0357 AM CST FRI FEB 15 2013
VALID 181200Z - 231200Z
...DISCUSSION...
AFTER SEVERAL DAYS OF DRYING NORTHWESTERLY LOW-LEVEL FLOW...A
GRADUAL MODIFICATION OF THE BOUNDARY LAYER OVER THE GULF OF MEXICO
APPEARS LIKELY TO COMMENCE EARLY NEXT WEEK...AS A SERIES OF
SIGNIFICANT SHORT WAVE TROUGHS BEGIN TO PROGRESS ACROSS THE NATION.
AN INITIAL IMPULSE PROGRESSING EAST OF THE ROCKIES LATE THIS COMING
WEEKEND...APPEARS LIKELY TO REACH THE PLAINS/MISSISSIPPI VALLEY
REGION TOO SOON...AND TOO FAR NORTH...FOR A SUBSTANTIVE RETURN FLOW
OF MOISTURE TO DEVELOP AND CONTRIBUTE TO AN APPRECIABLE RISK FOR
SEVERE THUNDERSTORMS. HOWEVER...MEDIUM RANGE FORECAST MODELS HAVE
BEEN FAIRLY CONSISTENT FOR SEVERAL DAYS NOW...SUGGESTING THAT THE
STRONG UPSTREAM IMPULSE WILL DIG INTO THE SOUTHERN GREAT
BASIN...BEFORE LIFTING EAST NORTHEASTWARD ACROSS THE CENTRAL AND
SOUTHERN ROCKIES/PLAINS AND MIDDLE MISSISSIPPI VALLEY DURING THE
MIDDLE TO LATTER PORTION OF NEXT WEEKEND. AT THIS POINT...TIMING
INTO THE PLAINS WEDNESDAY NIGHT...AS MORE FAVORABLE INLAND MOISTURE
RETURN BEGINS TO OCCUR OFF THE WESTERN GULF OF MEXICO...DOES NOT
APPEAR OPTIMAL FOR SEVERE WEATHER POTENTIAL. BUT...BY THURSDAY...AT
LEAST ON THE SOUTHERN FRINGE OF STRONGER HIGH-LEVEL DIFLUENCE AND
MID-LEVEL HEIGHT FALLS...THERE APPEARS A GOOD LIKELIHOOD THAT
LARGE-SCALE FORCING FOR UPWARD VERTICAL MOTION AND BOUNDARY LAYER
DESTABILIZATION WILL BECOME FAVORABLY JUXTAPOSED TO SUPPORT THE RISK
FOR SEVERE STORMS...INCLUDING POTENTIAL FOR AT LEAST ISOLATED
TORNADOES.
..KERR.. 02/15/2013
CLICK TO GET WUUS48 PTSD48 PRODUCT
weather.gov 
@NWSSPC
