Severe Storm Outlook Narrative (AC)
Issued by NWS

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000
ACUS48 KWNS 201001
SWOD48
SPC AC 201000

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0400 AM CST THU NOV 20 2014

VALID 231200Z - 281200Z

...DISCUSSION...
DAY 4...MODEL CONSENSUS IS THAT LEAD SHORTWAVE TROUGH INITIALLY OVER
THE MS VALLEY EARLY DAY 4 /SUNDAY/ WILL CONTINUE NEWD THROUGH THE OH
VALLEY AND GREAT LAKES REGION...WHILE A STRONG UPPER JET DROPS SEWD
THROUGH THE BASE OF THE LONGWAVE TROUGH. A SFC LOW WILL DEEPEN IN
ASSOCIATION WITH THE EJECTING LEAD WAVE BEFORE OCCLUDING OVER THE
GREAT LAKES. COLD FRONT WILL REACH THE MID-ATLANTIC SWWD INTO THE
NWRN GULF SUNDAY BEFORE MOVING OFF THE ATLANTIC SEABOARD MONDAY.
WIDESPREAD CONVECTION IS EXPECTED TO DEVELOP EARLY SUNDAY OVER THE
NRN GULF INTO THE SERN U.S. ALONG A BROAD WARM CONVEYOR BELT. WHILE
A SYNOPTIC WARM FRONT WILL DEVELOP INLAND...THE EFFECTIVE FRONT
SEPARATING THE MORE UNSTABLE PORTION OF THE WARM SECTOR FROM THE
RAIN COOLED BOUNDARY LAYER WILL LIKELY REMAIN NEAR THE GULF COAST
AREA. THIS SUGGESTS IT WILL LIKELY BE DIFFICULT TO ESTABLISH
SIGNIFICANT INSTABILITY INLAND. BEST THREAT FOR SEVERE STORMS WILL
PROBABLY BE FROM NRN FL INTO SRN GA...BUT CONFIDENCE IN A 30% OR
GREATER RISK AREA IS NOT PARTICULARLY HIGH AT THIS TIME. A SLIGHT
RISK WILL PROBABLY BE NEEDED FOR NRN FL INTO SRN GA IN LATER
UPDATES.

FOR MONDAY /DAY 5/ A FEW STORMS MAY DEVELOP IN VICINITY OF THE FRONT
FROM THE ERN CAROLINAS INTO SRN GA WHERE THE CIRCULATION ASSOCIATED
WITH A STRONG UPPER JET WILL INTERACT WITH THE BAROCLINIC ZONE.
THESE STORMS WILL BE EMBEDDED WITHIN STRONG UNIDIRECTIONAL WIND
FIELDS SUPPORTING A POTENTIAL SEVERE THREAT. HOWEVER...UNCERTAINTY
REGARDING THE THERMODYNAMIC ENVIRONMENT AND WHERE THE EFFECTIVE
BOUNDARY WILL SET UP PRECLUDES INTRODUCING A CATEGORICAL RISK AREA
FOR THIS UPDATE.

DAYS 6-8...BLOCKING PATTERN CHARACTERIZED BY A BROAD UPPER TROUGH
OVER THE ERN HALF OF THE U.S. SHOULD PERSIST THE REMAINDER OF THIS
PERIOD SUPPORTING MOSTLY OFFSHORE FLOW AND STABLE CONDITIONS INLAND.

..DIAL.. 11/20/2014


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