(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 141000
SPC AC 141000
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0400 AM CST THU NOV 14 2013
VALID 171200Z - 221200Z
...DISCUSSION...
SOME UNCERTAINTY LINGERS...BUT TRENDS IN THE MEDIUM RANGE FORECAST
GUIDANCE ARE INCREASINGLY SUGGESTIVE OF THE DEVELOPMENT OF AN
ENVIRONMENT SUPPORTIVE OF AN OUTBREAK OF SEVERE THUNDERSTORMS ACROSS
PARTS OF THE MIDDLE MISSISSIPPI VALLEY EASTWARD THROUGH MUCH OF THE
OHIO VALLEY ON SUNDAY. MOST GUIDANCE NOW APPEARS GENERALLY FASTER
WITH THE CONTINUED EASTWARD PROGRESSION OF A STRONG SHORT WAVE
TROUGH...FROM THE CENTRAL PLAINS EARLY SUNDAY TO THE LOWER GREAT
LAKES/UPPER OHIO VALLEY/CENTRAL APPALACHIANS REGION BY LATE SUNDAY
NIGHT. MOST MODELS ARE NOW SUGGESTIVE THAT THIS WILL BE ACCOMPANIED
BY STRONG SURFACE CYCLOGENESIS...WITH MOST RAPID SURFACE PRESSURE
FALLS ACROSS PARTS OF THE GREAT LAKES REGION AND OHIO VALLEY LATE
SUNDAY AFTERNOON INTO SUNDAY NIGHT.
A 90+ KT 500 MB JET STREAK NOSING THROUGH THE OHIO VALLEY...COUPLED
WITH STRENGTHENING SOUTHERLY WARM SECTOR 850 MB FLOW...PERHAPS IN
EXCESS OF 70 KTS ACROSS PARTS OF THE OHIO VALLEY INTO THE LOWER
GREAT LAKES...WILL CONTRIBUTE TO VERY STRONG DEEP LAYER WIND FIELDS
AND SHEAR. IT ALSO APPEARS INCREASINGLY PROBABLE THAT THIS WILL
COINCIDE WITH AN INFLUX OF SEASONABLY HIGH MOISTURE CONTENT AT LEAST
AS FAR NORTH AND EAST AS THE LOWER OHIO VALLEY...CONTRIBUTING TO
SUFFICIENT CAPE FOR VIGOROUS STORM DEVELOPMENT. SUPERCELLS WITH A
RISK FOR TORNADOES WILL BE POSSIBLE...PARTICULARLY IN EARLY STAGES
OF CONVECTIVE DEVELOPMENT...PERHAPS AS EARLY AS MID DAY ACROSS PARTS
OF THE MIDDLE MISSISSIPPI INTO LOWER OHIO VALLEY VALLEY.
EVENTUALLY...THOUGH...ACTIVITY PROBABLY WILL EVOLVE INTO A SQUALL
LINE WITH DAMAGING STRAIGHT-LINE WINDS BECOMING THE MOST PROMINENT
SEVERE THREAT. IT MAY NOT BE OUT OF THE QUESTION THAT THIS COULD
PROGRESS INTO PARTS OF THE MID ATLANTIC SEABOARD AND NORTHEAST LATE
SUNDAY NIGHT INTO MONDAY...BUT THIS IS STILL TOO UNCERTAIN TO
DELINEATE A REGIONAL SEVERE RISK AREA EAST OF THAT CURRENTLY
DEPICTED. THEREAFTER...CONVECTIVE POTENTIAL THROUGH THE REMAINDER
OF THE PERIOD APPEARS LOW.
..KERR.. 11/14/2013
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