DAY48SVR: Nws Storm Prediction Center Norman Ok

ACUS48 KWNS 150958
SWOD48
SPC AC 150957

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0357 AM CST SUN FEB 15 2009

VALID 181200Z - 231200Z

...DISCUSSION...

DAY 4...

STRONG SRN BRANCH UPPER JET WILL ADVANCE INTO THE LOWER MS...TN AND
OH VALLEYS WED WHERE IT WILL MERGE WITH NRN STREAM IMPULSES WITH
SUBSEQUENT CONSOLIDATION AND AMPLIFICATION OF A TROUGH OVER THE ERN
STATES WED NIGHT. SURFACE LOW TRACK WILL REMAIN TIED TO STRONGER
FORCING WITHIN UPPER JET EXIT REGION. THIS FEATURE WILL LIFT NE INTO
THE OH VALLEY OR GREAT LAKES REGION DURING THE DAY. TRAILING COLD
FRONT WILL SWEEP EWD THROUGH THE OH VALLEY AND SERN STATES. THOUGH
OVERALL PATTERN REMAINS SIMILAR AMONG THE MODELS...SOME DIFFERENCES
EXIST IN TIMING AND MESOSCALE DETAILS.

SEVERE WEATHER PROSPECTS REMAIN CONTINGENT PRIMARILY ON DEGREE OF
INSTABILITY THAT CAN DEVELOP IN WARM SECTOR. GULF FRONTAL INTRUSION
MONDAY WILL DELAY BOUNDARY LAYER MODIFICATION OVER THE WRN GULF. BY
WEDNESDAY AN AXIS OF PARTIALLY MODIFIED GULF AIR WILL ADVECT NWD
THROUGH THE LOWER MS VALLEY AND A PORTION OF THE SERN STATES ALONG A
STRONG SWLY LOW LEVEL JET. SEVERAL CLUSTERS OF STORMS MAY DEVELOP
ALONG AND EAST OF ADVANCING FRONT WITHIN THE LOW LEVEL CONFLUENT
FLOW REGIME FROM THE LOWER MS VALLEY INTO PARTS OF THE SERN STATES.
THIS ACTIVITY WILL BE EMBEDDED WITHIN STRONG KINEMATIC PROFILES AND
ANY SURFACE BASED STORMS COULD POSE A THREAT FOR SEVERE WEATHER.
WARM SECTOR INSTABILITY WILL LIKELY REMAIN MARGINAL DUE IN PART TO
WIDESPREAD CLOUDS. THE MARGINAL THERMODYNAMIC ENVIRONMENT AND
LIKELIHOOD THAT THE STRONGER FORCING WILL REMAIN NORTH OF MOIST AXIS
COULD SERVE AS POTENTIAL LIMITING FACTORS.

FARTHER NORTH INTO SRN PARTS OF THE OH VALLEY...COLDER AIR ALOFT AND
STRONGER FORCING WILL EXIST IN VICINITY OF UPPER JET EXIT REGION
WHICH COULD COMPENSATE FOR MORE LIMITED LOW LEVEL MOISTURE. IF
SURFACE HEATING COULD DEVELOP IN DRY SLOT...SOME POTENTIAL FOR
SURFACE BASED STORMS WOULD EXIST WITH A CORRESPONDING INCREASE IN
THE SEVERE TREAT. THIS AREA WILL CONTINUE TO BE MONITORED.

DAY 5-8...SEVERE POTENTIAL APPEARS LOW AT THIS TIME.

..DIAL.. 02/15/2009

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