ACUS02 KWNS 031728
SWODY2
SPC AC 031726
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1226 PM CDT WED JUN 03 2009
VALID 041200Z - 051200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER A PORTION OF THE CNTRL
HIGH PLAINS...
...THERE IS A SLGT RISK OF SVR TSTMS OVER A PORTION OF THE PACIFIC
NW REGION...
...SYNOPSIS...
LARGE SCALE UPPER PATTERN WILL REMAIN DOMINATED BY A BROAD TROUGH
FROM THE UPPER MS VALLEY THROUGH THE GREAT LAKES AND NERN U.S. AND A
CUTOFF LOW ALONG THE CA COAST THAT WILL DRIFT SLOWLY EAST. SHORTWAVE
RIDGE AXIS WILL EXTEND ALONG THE ROCKIES. FARTHER SOUTH A SRN STREAM
UPPER TROUGH WILL MOVE SLOWLY EWD THROUGH THE SERN STATES AND NRN
GULF REGION.
AT THE SURFACE A COLD FRONT SHOULD EXTEND FROM SRN VA SWWD THROUGH
SERN TX. THE WRN PORTIONS OF THIS BOUNDARY WILL ADVANCE SEWD WHILE
REMAINING NEARLY STATIONARY ACROSS SRN VA.
...CNTRL HIGH PLAINS AREA...
WITH RICHER GULF MOISTURE RESIDING SOUTH OF FRONTAL BOUNDARY ACROSS
SRN TX...ONLY MODIFIED CP AIR WITH 40S TO LOW 50S DEWPOINTS WILL
CHARACTERIZE THE BOUNDARY LAYER EAST OF THE HIGHER TERRAIN. PLUME OF
STEEP MID LEVEL LAPSE RATES WILL ADVECT EWD ABOVE THE BOUNDARY
LAYER AND IN CONJUNCTION WITH STRONG DIURNAL HEATING WILL CONTRIBUTE
TO AN AXIS OF MODEST INSTABILITY WITH 500-1000 J/KG MLCAPE.
THIS REGION WILL REMAIN WITHIN ZONE OF WEAK LARGE SCALE
FORCING...AND PRESENCE OF EML WILL LIKELY RESULT IN A CAP EAST OF
THE MOUNTAINS. THESE FACTORS COULD POTENTIALLY LIMIT STORM COVERAGE.
NEVERTHELESS...OROGRAPHIC FORCING DRIVEN IN PART BY DIABATIC HEATING
SHOULD RESULT IN ISOLATED-WIDELY SCATTERED THUNDERSTORM DEVELOPMENT
OVER THE HIGHER TERRAIN. BELT OF NWLY UPPER FLOW WILL STRENGTHEN TO
40-50 KT AS HEIGHT GRADIENT INCREASES BETWEEN UPPER RIDGE AND
IMPULSE MOVING SWD THROUGH SRN SASKATCHEWAN. LIGHT SELY LOW LEVEL
FLOW BENEATH BELT OF STRONGER WINDS ALOFT WILL CONTRIBUTE TO STORMS
MOVING OFF HIGHER TERRAIN INTO THE HIGH PLAINS WHERE THEY WILL HAVE
POTENTIAL TO INTENSIFY AS THE BOUNDARY LAYER DESTABILIZES. BULK
SHEAR OF 40-45 KT WILL SUPPORT SUPERCELL STRUCTURES WITH LARGE HAIL
AND ISOLATED DAMAGING WIND GUSTS THE PRIMARY THREATS.
...PACIFIC NW AREA...
IN-SITU MOISTURE WITH 40S DEWPOINTS BENEATH COLD AIR ALOFT /-14C TO
-15C AT 500 MB/ WILL CONTRIBUTE TO 500-1000 J/KG MLCAPE AS THE
BOUNDARY LAYER WARMS DURING THE AFTERNOON. A SERIES OF VORTICITY
MAXIMA ROTATING NWD THROUGH UPPER LOW AND RELATIVELY MOIST DEEP
LAYER PROFILES WILL RESULT IN A FAVORABLE ENVIRONMENT FOR STORMS TO
DEVELOP ALONG PREFERRED TERRAIN FEATURES AS THE ATMOSPHERE
DESTABILIZES. STORMS WILL BE EMBEDDED WITHIN BELT OF 35-40 KT E-SELY
MID-UPPER FLOW ALONG NRN PERIPHERY OF THE UPPER LOW WHICH IN
CONJUNCTION WITH STEEP LAPSE RATES AND 20+ TEMPERATURE - DEWPOINT
SPREADS WILL AUGMENT THE THREAT OF ISOLATED DAMAGING WIND. SOME OF
THE STRONGER STORMS MAY ALSO BECOME CAPABLE OF PRODUCING ISOLATED
LARGE HAIL.
...SERN STATES...
WIDESPREAD CLOUDS SND WEAK LAPSE RATES WILL RESULT IN A GENERALLY
MARGINAL THERMODYNAMIC ENVIRONMENT FOR SEVERE STORMS IN MOST OF THIS
REGION. NUMEROUS SHOWERS/STORMS WILL LIKELY DEVELOP ALONG AND SOUTH
OF FRONT AND IN ASSOCIATION WITH LARGE SCALE LIFT ASSOCIATED WITH
EWD ADVANCING UPPER TROUGH. WHERE SUFFICIENT DIABATIC HEATING
OCCURS...LOW LEVEL LAPSE RATES MAY STEEPEN ENOUGH TO SUPPORT A
THREAT OF ISOLATED STRONG WIND GUSTS.
A BELT OF STRONGER LOW-MID LEVEL FLOW IS FORECAST TO SHIFT FROM NRN
FL/SERN GA NEWD INTO THE ERN CAROLINAS IN ASSOCIATION WITH VORT MAX
LIFTING NEWD THROUGH UPPER TROUGH. NAM FORECAST 0-1 KM HODOGRAPHS
SUGGEST A THREAT OF LOW LEVEL MESOCYCLONES AND POTENTIAL ISOLATED
TORNADO RISK FROM SE GA THROUGH THE ERN CAROLINAS. HOWEVER...WARM
AIR ALOFT...POOR LAPSE RATES AND LIKELIHOOD OF WIDESPREAD CLOUDS
SHOULD POSE A LIMITING FACTOR FOR A MORE ROBUST SEVERE EVENT.
..DIAL.. 06/03/2009
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