DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 270647
SWODY3
SPC AC 270645

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0145 AM CDT THU MAR 27 2008

VALID 291200Z - 301200Z

..NO SVR TSTM AREAS FORECAST...

..SYNOPSIS...
MID/UPPER LEVEL CYCLONE THAT HAS BEEN PERSISTENT OVER GULF OF AK IS
FCST TO MOVE SEWD THEN EWD ACROSS PACIFIC NW THROUGH DAY-2.
PERTURBATION SHOULD REACH NRN ROCKIES BY 29/12Z...BRACKETED IN ITS
SRN SEMICIRCLE BY CYCLONICALLY CURVED...100-120 KT 250 MB SPEED MAX.
THIS FEATURE SHOULD MOVE EWD GENERALLY CLOSE TO MT/CANADA LINE
EARLY IN PERIOD...BEFORE TURNING NEWD ACROSS SRN PORTIONS SASK AND
MB.

ASSOCIATED/WELL-DEVELOPED SFC LOW IS FCST BY 29/12Z INVOF MT/WY
BORDER...WHICH LIKEWISE WILL EJECT NEWD...REACHING NEARLY VERTICAL
JUXTAPOSITION WITH MIDLEVEL LOW OVER MB BY END OF PERIOD. TRAILING
SFC COLD FRONT SHOULD MOVE SSEWD ACROSS NRN/CENTRAL HIGH PLAINS AND
EWD ACROSS DAKOTAS/WRN MN BEFORE END OF PERIOD. SECONDARY
LEE-SIDE/FRONTAL-WAVE LOW DEVELOPMENT IS LIKELY OVER CENTRAL HIGH
PLAINS INVOF NERN CO. CONSIDERABLE AGREEMENT EXISTS AMONG
OPERATIONAL/DETERMINISTIC AND VARIOUS SREF PACKAGES ON THIS SCENARIO
THROUGH APPROXIMATELY 30/00Z...WITH LOW BECOMING SOMEWHAT MORE
DIFFUSE AS IT SHIFTS SEWD ACROSS SWRN KS DURING ENSUING 12 HOURS.

MEANWHILE...FARTHER SE...SFC FRONTAL ZONE DISCUSSED IN DAY-1/DAY-2
OUTLOOKS IS FCST TO BECOME MORE DIFFUSE AND RETREAT NWD ACROSS SRN
PLAINS DURING THIS PERIOD. MOST FAVORABLE MOISTURE WILL REMAIN S OF
THIS BOUNDARY AND WELL DISPLACED FROM BOTH STRONGEST UPPER LEVEL
FORCING OVER NRN PLAINS...AND STRONGEST LOW LEVEL CONVERGENCE INVOF
CENTRAL HIGH PLAINS FRONT/LOW. FCST SOUNDINGS DO SUGGEST SUFFICIENT
HEATING AND LIFT...BARELY...TO SUPPORT POTENTIAL FOR HIGH-BASED
TSTMS DURING AFTERNOON ACROSS PORTIONS WRN NEB/NERN CO NEAR LOW AND
FRONT...WITH MLCAPES GENERALLY AOB 300 J/KG. SOME OF THIS ACTIVITY
MAY PERSIST EWD ACROSS NEB OVERNIGHT. LACK OF MORE ROBUST
MOISTURE/BUOYANCY PRECLUDES SVR OUTLOOK ATTM. WIDELY SCATTERED
TSTMS ALSO MAY OCCUR ALONG AND S OF WARM FRONT FROM SRN LOW PLAINS
TO MS DELTA REGION...LIMITED IN ORGANIZATION BY WEAKNESS OF BOTH
CONVERGENCE AND SHEAR IN LOW LEVELS.

.EDWARDS.. 03/27/2008

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