SPC AC 101241
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0741 AM CDT WED JUN 10 2009
VALID 101300Z - 111200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE SRN HIGH PLAINS TO
ACROSS THE MIDDLE MISSISSIPPI VALLEY/OHIO VALLEY AND CENTRAL
APPALACHIANS AND ADJACENT FOOTHILLS/PIEDMONT...
...SYNOPSIS...
BROAD BELT OF 40-50KT W/WSWLY FLOW EXTENDS FROM COAST-TO-COAST TODAY
BETWEEN LARGE SCALE TROUGHING OVER CANADA AND NRN BORDER
STATES...AND SUB-TROPICAL RIDGE OVER MEXICO/SRN TX AND THE ADJACENT
GULF OF MEXICO. NRN PERIPHERY OF THE SUB-TROPICAL RIDGE AXIS WILL
BECOME SUPPRESSED ACROSS THE SRN GREAT PLAINS TODAY AS A SHORT WAVE
TROUGH EJECTS NEWD FROM AZ/NM.
AT THE SFC...A COMPLEX QUASI-STATIONARY FRONTAL ZONE...FRACTURED IN
A NUMBER OF AREAS BY DIURNAL/EPISODIC CONVECTION...EXTENDS FROM ERN
CO FRONT RANGE SEWD TO KS/OK...AND THEN EWD TO THE LOWER OH VALLEY.
THE FRONT BECOMES A BIT MORE DIFFUSE FROM THE OH VALLEY ACROSS THE
APPALACHIANS TO THE EAST COAST.
TSTM DEVELOPMENT AND EVOLUTION ALONG/NEAR THE ENTIRE EXTENT OF THIS
FRONTAL ZONE WILL BE MODULATED BY SEVERAL COMPLEX FACTORS TODAY
INCLUDING: 1)FORCING ASSOCIATED WITH THE MORE SUBSTANTIAL SHORT WAVE
TROUGH MOVING OUT OF THE SOUTHWEST...AS WELL AS A WEAKER LEADING
LOW-AMPLITUDE SHORTWAVE MOVING FROM MO EWD TO THE OH VALLEY...2)
PLACEMENT/LOCATION OF RESIDUAL STORM OUTFLOW BOUNDARIES AND THEIR
LOCATION WITH RESPECT TO POTENTIAL FRONTAL WAVES/ENHANCED DEEP-LAYER
ASCENT...AND 3) LOW LEVEL MOISTURE AXES/DISCONTINUITIES INCLUDING
RESIDUAL DRYLINE INFLUENCE ANALYZED ACROSS TX PNHDL/WRN OK...AND
DEEPER MOISTURE SURGE SITUATED FROM TX NWD/NEWD TO THE OZARKS.
...SRN PLAINS...
IT IS DIFFICULT TO BE TOO SPECIFIC WITH REGARD TO STORM
DEVELOPMENT/CHARACTER ACROSS THIS LARGE REGION TODAY GIVEN
COMPLEXITIES ALREADY MENTIONED. LARGE SCALE LIFT WITH THE MID/UPPER
TROUGH EJECTING FROM AZ/NM WAS ALREADY CONTRIBUTING TO ISOLATED
STORM DEVELOPMENT OVER A BROAD REGION. RECENT DEVELOPMENT WAS ALSO
INCREASING ALONG CONFLUENCE ZONE FROM TRANS-PECOS AREA NEWD ALONG
THE CAPROCK WHERE LOW LEVEL MOISTURE SURGE WAS OVERCOMING DRIER AIR
IN THE WAKE OF DRYLINE SURGE THAT OCCURRED ON TUESDAY.
STRENGTHENING BACKGROUND ASCENT ON THE LARGE SCALE WILL SUPPORT AN
INCREASE IN STORM COVERAGE THROUGH THE DAY. WITH SURFACE LOW
PRESSURE FORECAST TO PERSIST ACROSS TX/OK...AND THE FRONTAL ZONE
SITUATED ACROSS THE PNHDLS AND NRN OK...EXPECT MORE VIGOROUS AND
ORGANIZED STORMS TO BECOME MOST PREVALENT NEAR THESE FEATURES AND
BOUNDARIES. STORM INTENSITY IN TX MAY BE LIMITED BY SUBSTANTIAL
CONVECTIVE INHIBITION AND WIDESPREAD CLOUD COVER. A CORRIDOR OF
STRONGER SURFACE HEATING/DESTABILIZATION MAY OCCUR FROM TX PNHDL
ACROSS WRN OK...AND NEAR THE FRONT IN OK/SRN KS WHERE LATEST
SATELLITE IMAGERY SUGGESTS MORE LIMITED CLOUD COVER EXISTS THIS
MORNING.
STORMS SHOULD BECOME INCREASINGLY ORGANIZED AS MID LEVEL FLOW
STRENGTHENS ACROSS THE ENTIRE WARM SECTOR THROUGH THE DAY. STORM
SCALE AND MESOSCALE INFLUENCES YET TO DEVELOP/OCCUR WILL PLAY A
SIGNIFICANT ROLE IN HOW AND WHERE SEVERE WEATHER THREAT IS REALIZED.
IN ADDITION TO WIND...LARGE HAIL...AND SOME TORNADO
POTENTIAL...UPSCALE ORGANIZATION INTO AN MCS OR TWO APPEARS LIKELY
FROM KS TO TX LATER TODAY AND INTO TONIGHT. IT IS POSSIBLE THAT
HIGHER SEVERE WEATHER PROBABILITIES MIGHT BE DEPICTED IN LATER
OUTLOOKS AS STORMS INCREASE AND ORGANIZE THROUGH LATER TODAY.
...MIDWEST/LOWER OH VALLEY...
A ZONE OF ENHANCED STORM POTENTIAL MAY BECOME ESTABLISHED FROM MO/IL
EWD ACROSS THE LOWER OH VALLEY THROUGH THE DAY. LIFT WITH THE
LOW-AMPLITUDE DISTURBANCE NOW DRIVING STORMS ACROSS SERN MO WILL
CONTINUE TO PROVIDE SUPPORT FOR TSTM DEVELOPMENT ALONG THE RESIDUAL
FRONTAL BOUNDARY DRAPED ACROSS THE REGION. DESPITE WIDESPREAD CLOUDS
ACROSS THE REGION ATTM...POCKETS OF GREATER SURFACE-BASED
DESTABILIZATION APPEAR POSSIBLE GIVEN RICH LOW LEVEL MOISTURE AND
PERSISTENT PLUME OF STEEP LAPSE RATES. EFFECTIVE FLOW AS FORECAST
WILL SUPPORT SUPERCELLS AND LINE SEGMENTS WITH HAIL AND WIND DAMAGE
POTENTIAL.
...EAST...
ANOTHER DAY OF DIURNAL/TERRAIN-INDUCED DEEP CONVECTION IS FORECAST
FROM PA/WV SWD ACROSS THE CAROLINAS. STORMS WILL LIKELY INITIATE
ACROSS THE HIGHER TERRAIN EARLY AIDED BY DIFFERENTIAL
HEATING...BROADLY DIFFLUENT MID/UPPER LEVEL FLOW...AND WEAK HEIGHT
FALLS. THIS ACTIVITY WILL THEN MOVE EAST INTO LOWER ELEVATIONS WHERE
STRONG HEATING AND DESTABILIZATION WILL CONTRIBUTE DOWNBURST AND
SEVERE HAIL POTENTIAL. DEEP-LAYER SHEAR ON THE ORDER OF 20-30KT
INDICATES PRIMARY CONVECTIVE MODE SHOULD BE MULTICELLULAR.
HOWEVER...SOME LOCAL/GREATER ORGANIZATION IS POSSIBLE AS STORM
MERGERS GENERATE EXPANDING/STRONG COLD POOLS.
...HIGH PLAINS...
MOIST UPSLOPE FLOW WILL AGAIN AID STORM DEVELOPMENT ACROSS CO/SERN
WY AND ADJACENT AREAS OF NE/KS TODAY WITHIN SUFFICIENTLY SHEARED
FLOW FOR SUPERCELLS. WHILE LIFT WITH THE APPROACHING SHORT WAVE
TROUGH MAY LEAD TO MORE NUMEROUS STORMS COMPARED TO PRIOR
DAYS...INCREASING CLOUD COVER WITH THIS SYSTEM MAY ALSO ACT TO
INHIBIT GREATER DESTABILIZATION. NONETHELESS...PRESENCE OF LARGE
SCALE ASCENT...LOCALLY STRONGER LOW LEVEL SHEAR ALONG RESIDUAL
FRONTAL ZONE...AND STEEP LAPSE RATES...SHOULD LEAD TO AT LEAST A FEW
SEVERE STORMS WITH HAIL AND HIGH WIND POTENTIAL. IT IS POSSIBLE THAT
THIS CONVECTION COULD CONGEAL INTO A SMALL MCS AND MOVE ACROSS WRN
KS/NE LATER TONIGHT.
..CARBIN/HURLBUT.. 06/10/2009
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
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