SPC AC 241958
DAY 1 CONVECTIVE OUTLOOK CORR 1
NWS STORM PREDICTION CENTER NORMAN OK
0258 PM CDT THU APR 24 2008
VALID 242000Z - 251200Z
...THERE IS A MDT RISK OF SVR TSTMS LATE THIS AFTN AND EVE ACROSS
PARTS OF SOUTHERN NEBRASKA...NORTHERN AND CENTRAL KANSAS....
...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MODERATE RISK
AREA ACROSS THE CNTRL/SRN PLAINS THRU THE MID MO VALLEY....
CORRECTED TO ADJUST GEN TSTM LINE IN ORDER TO CORRECT NDFD GRID
...SYNOPSIS...
IN THE WAKE OF AN INITIAL POLAR SHORT WAVE IMPULSE...NOW LIFTING
ACROSS THE CENTRAL CANADIAN/U.S. BORDER AREA...A SURFACE COLD FRONT
HAS ADVANCED EAST OF THE NORTHERN PLAINS RED RIVER VALLEY...AND
SOUTHEASTWARD INTO THE MID MISSOURI VALLEY AND NORTH CENTRAL HIGH
PLAINS. SOUTHWARD SURGE MAY BE A BIT QUICKER THAN EARLY
PROGGED...AND FRONT/DRY LINE INTERSECTION BY 25/00Z MAY END UP IN
THE VICINITY OF NORTHWEST KANSAS. A BIT FARTHER SOUTH...A SURFACE
LOW ALONG THE DRY LINE IS EXPECTED TO CONSOLIDATE OVER SOUTHWEST
KANSAS...AS THE VIGOROUS UPSTREAM POLAR IMPULSE OVER THE GREAT BASIN
TURNS EASTWARD TOWARD THE CENTRAL ROCKIES. AS THIS OCCURS...AND
SURFACE HEATING CONTINUES ACROSS THE CENTRAL/SOUTHERN HIGH
PLAINS...THE DRY LINE IS EXPECTED TO SHARPEN UP ACROSS
SOUTHWEST/SOUTH CENTRAL KANSAS AND WEST CENTRAL OKLAHOMA INTO
NORTHWEST TEXAS.
SOUTH OF COLD FRONT...AND EAST OF DRY LINE...A MOIST BOUNDARY LAYER
AIR MASS CONTINUES TO DESTABILIZE BENEATH A STRONG CAPPING ELEVATED
MIXED LAYER WHICH HAS EMANATED FROM THE ROCKIES/PLATEAU REGION. BY
LATE AFTERNOON...MIXED LAYER CAPE IN EXCESS OF 2000 J/KG SHOULD BE
FAIRLY WIDESPREAD ACROSS THE CENTRAL/SOUTHERN PLAINS. IT STILL
SEEMS PROBABLE THAT CONSIDERABLE INHIBITION WILL PERSIST...WHILE
DEEP LAYER AND LOW-LEVEL SHEAR PROFILES GROW INCREASINGLY FAVORABLE
FOR SUPERCELLS...AS A SOUTHERLY LOW-LEVEL JET STRENGTHENS...AND A
BROAD BELT OF 40-50 KT WESTERLY 500 MB FLOW NOSES INTO THE CENTRAL
PLAINS.
...SOUTHWEST KANSAS INTO NORTHWEST TEXAS...
MODELS HAVE BEEN PERSISTENT IN INDICATING LITTLE IN THE WAY OF
CONVECTIVE QPF ACROSS REGION. THIS APPEARS TO BE THE PRIMARY
CONTRIBUTING FACTOR TO THE UNCERTAINTY AND INCONSISTENCY IN THE
CONVECTIVE OUTLOOK. AND...IT CERTAINLY SUGGESTS WIDESPREAD
CONVECTIVE DEVELOPMENT IS UNLIKELY. HOWEVER...THE LARGE-SCALE
SYNOPTIC PATTERN BENEATH DIFLUENT CYCLONIC UPPER FLOW IS SUPPORTIVE
OF POTENTIAL FOR AT LEAST ISOLATED TO WIDELY SCATTERED SUPERCELL
FORMATION WHERE CAPPING LOCALLY WEAKENS ALONG THE DRY LINE. IF THIS
OCCURS...SUSTAINED STORM DEVELOPMENT APPEARS LIKELY IN AN
ENVIRONMENT FAVORABLE FOR THE PRODUCTION OF VERY LARGE HAIL AND
LOCALLY DAMAGING WIND GUSTS. HODOGRAPHS ARE EXPECTED TO BECOME
SUPPORTIVE OF TORNADIC ACTIVITY FROM PARTS OF SOUTHWEST INTO CENTRAL
KANSAS...WITH POTENTIAL LESS CERTAIN WITH SOUTHWARD EXTENT ACROSS
OKLAHOMA INTO NORTHWEST TEXAS. WINDOW OF OPPORTUNITY FOR CONVECTIVE
DEVELOPMENT WILL PROBABLY CLOSE AS INHIBITION STRENGTHENS AGAIN WITH
THE LOSS OF DAYTIME HEATING...AFTER 25/02-03Z.
...SOUTHERN NEBRASKA AND PARTS OF NORTHERN/CENTRAL KANSAS...
OTHERWISE...THE COLD FRONT AND COLD FRONT/DRY LINE INTERSECTION ARE
STILL EXPECTED TO PROVIDE THE FOCUS FOR THE INITIATION OF STORMS
LATE THIS AFTERNOON. A FEW SUPERCELLS WITH THE POTENTIAL FOR VERY
LARGE HAIL/DAMAGING WIND GUSTS AND TORNADOES SEEM PROBABLE WITH
INITIAL DEVELOPMENT...BEFORE INCREASING MID/UPPER FORCING SUPPORTS
INCREASINGLY WIDESPREAD CONVECTIVE DEVELOPMENT. A GRADUAL
CONSOLIDATION OF ACTIVITY INTO AN EASTWARD ADVANCING MESOSCALE
CONVECTIVE SYSTEM APPEARS POSSIBLE THIS EVENING...WITH THERMODYNAMIC
PROFILES FAVORABLE FOR STRONG SURFACE COLD POOL DEVELOPMENT...AND AN
ACCOMPANYING RISK FOR BROADER SCALE DAMAGING WINDS.
..KERR.. 04/24/2008
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z
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