Monday, May 18, 2009

DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 180730
SWODY3
SPC AC 180728

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0228 AM CDT MON MAY 18 2009

VALID 201200Z - 211200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
AN AMPLIFIED/STAGNANT UPPER FLOW REGIME WILL CONTINUE TO PREVAIL
ACROSS THE SOUTHERN TWO-THIRDS OF THE LOWER 48 INTO WEDNESDAY...AS A
MEANDERING UPPER LOW REMAINS IN THE VICINITY OF FL...WITH ANOTHER
SLOW MOVING UPPER LEVEL LOW POTENTIALLY DEVELOPING NORTHEASTWARD
ACROSS THE SOUTHWEST DESERTS/NORTHWEST MEXICO. FARTHER NORTH...A
SHORTWAVE TROUGH WILL CONTINUE TO SPREAD EASTWARD ACROSS THE CENTRAL
CANADIAN PROVINCES AND ADJACENT NORTHERN PLAINS/UPPER MIDWEST IN
ASSOCIATION WITH THE MAIN BELT OF STRONGER WESTERLIES.

...NORTH CENTRAL PLAINS TO UPPER MIDWEST...
AS THE AFOREMENTIONED SHORTWAVE TROUGH STEADILY ADVANCES
NORTHEASTWARD ACROSS THE NORTHERN PLAINS/UPPER MIDWEST...THE
ASSOCIATED COLD FRONT WILL SPREAD SOUTH-SOUTHEASTWARD ACROSS THE
NORTH CENTRAL PLAINS AND UPPER MIDWEST. AIDED BY THE GRADUAL DECAY
OF THE UPPER RIDGE AND STRONG AFTERNOON/BOUNDARY LAYER
HEATING...MAINLY ISOLATED TSTMS SHOULD DEVELOP ALONG/JUST NORTH OF
THE SOUTHEAST ADVANCING FRONT ACROSS SD/NORTHERN NEB...AND PERHAPS
IN VICINITY OF A SHARPENING LEE TROUGH AND/OR VIA EARLY ONSET OF
POST-FRONTAL UPSLOPE REGIME ACROSS THE WESTERN NEB/NORTHEAST CO
VICINITY. THE STRONGEST SHEAR WILL LAG THE FRONT...BUT MODEST
MOISTURE /SURFACE DEWPOINTS MAINLY IN THE 40S F/ AND DEEP MIXING
COULD SUPPORT SOME MULTICELLULAR STORMS CAPABLE OF STRONG
GUSTS/HAIL. ANY SUCH THREAT WOULD LIKELY DIMINISH BY AROUND SUNSET.

FARTHER NORTHEAST...AWAY FROM THE HIGH PLAINS AND DEEPER BOUNDARY
LAYER MIXING...MID LEVEL CAPPING AND RELATIVELY MORE UNCERTAIN
SURFACE-BASED CONVECTIVE INITIATION PRECLUDES ANY LOW SEVERE
PROBABILITIES INTO MN AT THIS TIME.

...SOUTHERN FL PENINSULA...
SOME STRONG TSTMS MAY REMAIN POSSIBLE INTO WEDNESDAY ACROSS THE
SOUTHERN HALF OF THE FL PENINSULA. FORECAST UNCERTAINTIES WITH THE
EVOLUTION OF THE PARENT UPPER LOW OFF THE FL WEST COAST...AND
INHERENT UNKNOWNS REGARDING THE EXTENT OF DAY 2 CLOUD
COVER/PRECIPITATION...PRECLUDE ANY LOW SEVERE PROBABILITIES AT THIS
TIME.

..GUYER.. 05/18/2009

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