Severe Storm Outlook Narrative (AC)
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12
000
ACUS48 KWNS 170956
SWOD48
SPC AC 170955

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0355 AM CST WED DEC 17 2014

VALID 201200Z - 251200Z

...DISCUSSION...
MODEL GUIDANCE CONTINUES TO SUGGEST THAT SURFACE FRONTAL WAVE
DEVELOPMENT...LIKELY NEAR THE GULF COAST BY 12Z SATURDAY...WILL
REMAIN WEAK AS IT MIGRATES ACROSS THE SOUTH ATLANTIC COAST BY 12Z
SUNDAY.  AND SEVERE WEATHER POTENTIAL INTO AT LEAST EARLY NEXT WEEK
SEEMS LIKELY TO REMAIN LOW TO NEGLIGIBLE.  THEREAFTER...THE
LARGE-SCALE PATTERN EVOLUTION BECOMES INCREASINGLY UNCLEAR.

THE MEDIUM RANGE MODELS CONTINUE TO STRUGGLE WITH DEVELOPMENTS OVER
THE MID-LATITUDE PACIFIC...WHERE THE SPREAD OF POSSIBLE SOLUTIONS
REMAINS LARGE CONCERNING THE AMPLIFICATION OF SHORT WAVE
PERTURBATIONS EMANATING FROM AN INITIALLY ZONAL...INTENSE UPPER JET.
 IT STILL APPEARS THAT THIS PATTERN WILL BREAK DOWN INTO A BLOCKIER
REGIME ACROSS THE CENTRAL AND EASTERN PACIFIC.  THE DETAILS...AND
THE INFLUENCE ON THE DOWNSTREAM PATTERN ACROSS NORTH
AMERICA...REMAIN UNCERTAIN.

CURRENT TRENDS SEEM TO CONTINUE TO POINT TO LARGE-SCALE UPPER RIDGE
AMPLIFICATION ALONG THE PACIFIC COAST FOLLOWED BY MAJOR UPPER TROUGH
AMPLIFICATION EAST OF THE ROCKIES...WHICH MAY BE CAPABLE OF
SUPPORTING STRONG CYCLOGENESIS EAST OF THE MISSISSIPPI VALLEY.  SOME
SCENARIOS HAVE INCLUDED RAPID SURFACE LOW DEEPENING FROM THE LOWER
MISSISSIPPI VALLEY THROUGH THE GREAT LAKES REGION...THAT COULD BE
ACCOMPANIED BY ORGANIZED SEVERE WEATHER POTENTIAL ACROSS PARTS OF
THE SOUTHEAST DURING THE MIDDLE TO LATER PORTIONS OF NEXT WEEK
/INCLUDING CHRISTMAS EVE AND CHRISTMAS DAY/.  HOWEVER...LARGELY DUE
TO PREDICTABILITY ISSUES AT THIS POINT...SEVERE PROBABILITIES REMAIN
TOO LOW TO DELINEATE ANY REGIONAL SEVERE RISK AREAS.

..KERR.. 12/17/2014



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.