SPC AC 280544
DAY 2 CONVECTIVE OUTLOOK CORR 1
NWS STORM PREDICTION CENTER NORMAN OK
1244 AM CDT SAT JUN 28 2008
VALID 291200Z - 301200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF THE NERN...MID
ATLANTIC AND SERN STATES...
CORRECTED FOR PROBABILITY GRAPHIC
...SYNOPSIS...
HIGHLY AMPLIFIED UPPER PATTERN WILL CONTINUE INTO SUNDAY WITH LARGE
UPPER TROUGH OVER THE ERN U.S. WITH A CORRESPONDING UPPER RIDGE OVER
THE INTERMOUNTAIN WEST. AN UPPER LOW WILL ALSO PERSIST OVER THE ERN
PACIFIC. AT THE SURFACE A FRONT WILL EXTEND FROM AN OCCLUDED LOW IN
SERN CANADA SWWD THROUGH NY...THE APPALACHIANS AND TX EARLY SUNDAY.
THIS BOUNDARY WILL CONTINUE EWD AND SWD INTO NEW ENGLAND...CAROLINAS
AND THE SERN U.S. WHILE TX PORTION OF FRONT WILL LIKELY STALL.
...MID ATLANTIC THROUGH NERN STATES...
UPPER JET IS FORECAST TO LIFT NEWD ALONG ERN PERIPHERY OF THE UPPER
TROUGH INTO THE NERN U.S. DURING THE DAY. SOME CONVECTION MAY STILL
BE ONGOING EARLY SUNDAY ALONG OR JUST AHEAD OF FRONT ACROSS PARTS OF
THE OH VALLEY AND NERN STATES. WEAK MID LEVEL LAPSE RATES WITH -7C
TO -8C TEMPERATURES AT 500 MB AND POTENTIAL FOR AREAS OF CLOUDS WILL
LIKELY LIMIT OVERALL MAGNITUDE OF INSTABILITY. HOWEVER...WITH UPPER
60S LOW-LEVEL DEWPOINTS IN PLACE...MLCAPE FROM 1500-2000 J/KG WILL
BE POSSIBLE WHERE SUFFICIENT BOUNDARY LAYER WARMING OCCURS. WHILE
THE STRONGER FLOW WILL REMAIN POST FRONTAL...BULK SHEAR MAY INCREASE
TO 35-40 KT...ESPECIALLY OVER PARTS OF NEW ENGLAND AS THE MID LEVEL
JET LIFTS NEWD. VERTICAL SHEAR PROFILES ARE FORECAST TO REMAIN
LARGELY UNIDIRECTIONAL...BUT THE 0-1 KM HODOGRAPHS MAY BECOME
SUFFICIENT FOR A THREAT OF LOW LEVEL MESOCYCLONES OVER PARTS OF NEW
ENGLAND WHERE THE LOW LEVEL JET IS FORECAST TO INTENSIFY. STORMS
WILL LIKELY REDEVELOP BY MID-DAY AS THE ATMOSPHERE DESTABILIZES WITH
STORMS EVOLVING INTO CLUSTERS...LINE SEGMENTS AS WELL AS SOME
DISCRETE CELLS. PRIMARY THREAT APPEARS TO BE DAMAGING WIND...BUT
ISOLATED LARGE HAIL AS WELL AS A TORNADO OR TWO MAY ALSO BE
POSSIBLE...ESPECIALLY OVER THE NERN STATES WHERE THE SUPERCELL
THREAT APPEARS SOMEWHAT GREATER.
...SERN STATES...
VORT MAX IS FORECAST TO ROTATE SEWD THROUGH BASE OF UPPER TROUGH
INTO THE TN VALLEY WITH MODEST HEIGHT FALLS DOWNSTREAM OVER THE SERN
STATES. MODELS INDICATE A 30-40 KT WLY LOW LEVEL JET WILL PERSIST
DURING THE AFTERNOON OVER PARTS OF THE SERN STATES AND CAROLINAS.
STORMS WILL LIKELY BE ONGOING WITHIN ZONE OF ASCENT IN VICINITY OF
THE FRONT ACROSS THE TN VALLEY EARLY SUNDAY. DESPITE WEAK MID-LEVEL
LAPSE RATES...RICH LOW LEVEL MOISTURE AND DIABATIC HEATING WILL
CONTRIBUTE TO MODERATE INSTABILITY IN WARM SECTOR AND ONGOING STORMS
WILL LIKELY INTENSIFY AND DEVELOP SEWD DURING THE AFTERNOON. THE
WARM SECTOR WILL SHIFT SOUTH OF THE STRONGER FLOW ALOFT WITH WEAK
VERTICAL SHEAR EXPECTED...BUT STRONGER MOMENTUM ALONG THE LOW LEVEL
JET AXIS MAY ENHANCE DAMAGING WIND POTENTIAL AS LOW-LEVEL LAPSE
RATES STEEPEN. SEVERE THREAT SHOULD DIMINISH BY LATE EVENING AS THE
BOUNDARY LAYER COOLS.
...SRN PLAINS AND SRN HIGH PLAINS...
STORMS ARE EXPECTED TO REDEVELOP ALONG AND SOUTH OF FRONT OVER CNTRL
THROUGH S TX AS WELL AS OVER THE HIGHER TERRAIN OF NM. WARM
TEMPERATURES ALOFT WILL LIMIT 700-500 MB LAPSE RATES EXCEPT OVER THE
HIGHER TERRAIN OF NM AND AZ. MLCAPE WILL RANGE FROM NEAR 1000 J/KG
OVER NM TO 1500-2000 J/KG OVER TX WHERE RICHER LOW LEVEL MOISTURE
WILL EXIST. WEAK VERTICAL SHEAR WILL LIMIT STORM ORGANIZATION...BUT
ISOLATED DOWNBURSTS AND SMALL HAIL WILL BE POSSIBLE WITH THE
STRONGER STORMS.
...PACIFIC NW...
VORTICITY MAXIMA WILL CONTINUE TO LIFT NWD THROUGH NRN CA AND THE
PACIFIC NW ALONG ERN PERIPHERY OF UPPER LOW THAT WILL EXIST OFF THE
WRN U.S. COAST. POTENTIAL WILL EXIST FOR ISOLATED HIGH BASED STORMS
TO DEVELOP AS THE ATMOSPHERE DESTABILIZES DURING THE LATE AFTERNOON
AND EVENING...ESPECIALLY OVER THE HIGHER TERRAIN. ISOLATED STRONG
WIND GUSTS AND HAIL MAY ACCOMPANY SOME OF THE STRONGER STORMS.
..DIAL.. 06/28/2008
CLICK TO GET WUUS02 PTSDY2 PRODUCT
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z
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