DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 250731
SWODY3
SPC AC 250730

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0230 AM CDT WED APR 25 2012

VALID 271200Z - 281200Z

...SYNOPSIS...
MODELS INDICATE THAT THE LARGE-SCALE MID/UPPER FLOW PATTERN WILL
REMAIN BLOCKY THROUGH THIS FORECAST PERIOD...WITH A NUMBER OF
EMBEDDED SMALLER SCALE DEVELOPMENTS REMAINING UNCERTAIN. THIS
INCLUDES THE SUBSEQUENT EVOLUTION OF A HIGH CENTER...WHICH IS
EXPECTED TO DEVELOP OVER THE CENTRAL CANADIAN PROVINCES BY 12Z
FRIDAY...THE SOUTHERN PORTION OF A SPLITTING UPPER IMPULSE MIGRATING
INLAND ACROSS THE PACIFIC NORTHWEST AND NORTHERN INTERMOUNTAIN
REGION...AND ANOTHER LOW EMERGING FROM THE LOWER LATITUDE PACIFIC.
AFTER INITIALLY MAINTAINING ITS CYCLONIC CIRCULATION...MODELS ARE
SUGGESTIVE THAT THE SOUTHERN FEATURE MAY ELONGATE OVER THE MID
MISSOURI VALLEY FRIDAY...TO THE SOUTH OF THE HIGH...WHILE THE HIGHER
LATITUDE IMPULSE REDEVELOPS INTO THE MORE PROMINENT LOW ACROSS THE
NORTHERN ROCKIES.

SOUTH/EAST OF THE HIGH CENTER...AND WEST OF A BROADENING UPPER
CLOSED LOW OVER SOUTHEAST CANADA AND THE NORTHEASTERN U.S...COLD
SURFACE RIDGING MAY NOSE AS FAR SOUTH AS THE MIDDLE MISSISSIPPI AND
LOWER OHIO VALLEYS. AT THE SAME TIME...CONTINUED GRADUAL MOISTENING
OF THE BOUNDARY LAYER OVER THE GULF OF MEXICO MAY CONTINUE...BUT A
SUBSTANTIVE INLAND RETURN FLOW STILL APPEARS UNLIKELY.

...CENTRAL PLAINS INTO MIDDLE MISSISSIPPI VALLEY...
GIVEN UNCERTAINTIES ASSOCIATED WITH BOTH THE EVOLVING UPPER PATTERN
AND THE MAGNITUDE OF THE AVAILABLE LOW-LEVEL MOISTURE...
CONTINUATION OF SEVERE POTENTIAL DEVELOPING ON THURSDAY ACROSS THE
CENTRAL HIGH PLAINS REMAINS UNCLEAR...AS A SURFACE WAVE DEVELOPS
EASTWARD ALONG A FRONT INTO THE LOWER PLAINS AND MIDDLE MISSISSIPPI
VALLEY. AT LEAST SOME SIGNAL EXISTS IN THE GUIDANCE FOR A LATE
AFTERNOON ISOLATED SUPERCELL THREAT...AND SUBSEQUENT UPSCALE GROWTH
OF A MESOSCALE CONVECTIVE SYSTEM DURING THE EVENING...LOW SEVERE
PROBABILITIES APPEAR WARRANTED. BUT...THERE IS NOT ENOUGH
CONFIDENCE FOR SLIGHT RISK PROBABILITIES AT THE PRESENT TIME.

..KERR.. 04/25/2012

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