Report Created From Product: DY2TWOUS
ACUS02 KWNS 311654
SWODY2
SPC AC 311651
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1151 AM CDT FRI JUL 31 2009
VALID 011200Z - 021200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF OK...N TX...FAR
SWRN MO...AR...NWRN LA...
...SYNOPSIS...
LONGWAVE TROUGH /ANCHORED BY VORTEX OVER ONTARIO/ WILL BE MAINTAINED
E OF THE ROCKIES...DOWNSTREAM FROM MIDLEVEL RIDGING FROM WRN CANADA
INTO THE GREAT BASIN. FARTHER W...A DEEP-LAYER LOW WILL PERSIST OFF
THE CA COAST. WITHIN THIS PATTERN...THE MOST SIGNIFICANT SHORT WAVE
TROUGH WILL TRANSLATE EWD THROUGH THE GREAT LAKES WITH TRAILING
EXTENSION OF THIS FEATURE PROGRESSING FROM THE CNTRL PLAINS INTO OH
VALLEY.
AT THE SURFACE...COLD FRONT ATTENDANT TO ABOVE-MENTIONED SHORT WAVE
TROUGH WILL PROGRESS EWD THROUGH THE GREAT LAKES AND OH VALLEY...AND
MORE SEWD THROUGH THE OZARK PLATEAU. THE WRN EXTENSION OF BOUNDARY
WILL PIVOT ANTI-CYCLONICALLY OVER THE SRN HIGH PLAINS.
...OK/N TX INTO THE OZARK PLATEAU AND ARKLATEX...
STALLED FRONTAL BOUNDARY CURRENTLY ACROSS CNTRL/ERN TX INTO THE
LOWER MS VALLEY WILL LIKELY RETREAT NWD IN ADVANCE OF CNTRL PLAINS
COLD FRONT...ALLOWING FOR THE RETURN OF RICH BOUNDARY LAYER MOISTURE
/DEWPOINTS IN THE UPPER 60S TO LOWER 70S/ INTO AT LEAST INTO OK/AR.
EML/STEEP MIDLEVEL LAPSE RATES WILL REMAIN CONFINED TO THE
ROCKIES...BUT DAYTIME HEATING COUPLED WITH THIS MOISTURE WILL LIKELY
CONTRIBUTE TO A MODERATELY UNSTABLE AIR MASS WITH MLCAPE APPROACHING
1500-2500 J/KG.
WHILE TSTMS ARE EXPECTED TO BE ONGOING ALONG COLD FRONT SAT
MORNING...IT APPEARS THE GREATEST SEVERE THREAT WILL NOT OCCUR UNTIL
MID/LATE AFTERNOON INTO EVENING AS COLD FRONT BEGINS TO ENCOUNTER
THE MORE MOIST/UNSTABLE BOUNDARY LAYER. DEEP ASCENT WILL BE
AUGMENTED BY GLANCING INFLUENCE OF SHORT WAVE TROUGH MOVING THROUGH
THE OZARK PLATEAU/MID MS VALLEY...SUPPORTING CLUSTERS OF
STRONG/SEVERE STORMS. REGION WILL RESIDE ALONG SRN FRINGE OF MODEST
/30-35 KT/ MIDLEVEL FLOW WITH VERTICAL SHEAR MAGNITUDES ON THE
MARGINS OF THAT SUPPORTIVE OF MORE SUSTAINED/ORGANIZED STORMS. HAIL
AND DAMAGING WIND GUSTS WILL BE THE PRIMARY SEVERE THREATS THROUGH
SAT EVENING.
...UPPER GREAT LAKES INTO MIDWEST...
STRONGER FORCING ASSOCIATED WITH SHORT WAVE TROUGH SHOULD SERVE TO
ENHANCE COLD FRONTAL CONVERGENCE/ASCENT WITH SCATTERED STORMS
DEVELOPING ALONG BOUNDARY THROUGH THE DIURNAL HEATING CYCLE. WHILE
MOISTURE/INSTABILITY WILL INCREASE WITH SWD/SWWD EXTENT ALONG
FRONTAL ZONE...VERTICAL SHEAR WILL DECREASE. AS SUCH...SETUP WILL
FAVOR THE DEVELOPMENT OF A FEW STRONG/MARGINALLY SEVERE STORMS SAT
AFTERNOON WITH THE THREAT FOR SOME HAIL/GUSTY WINDS.
...SERN STATES...
A MOIST AND MODERATELY UNSTABLE AIR MASS /MLCAPE OF 1000-2000 J PER
KG/ WILL EXIST ALONG AND E/S OF FRONTOLYTICAL SURFACE BOUNDARY
STRETCHED ACROSS REGION. BELT OF HIGHER MOMENTUM MIDLEVEL FLOW
ASSOCIATED WITH OZARKS/MID MS VALLEY SHORT WAVE TROUGH WILL REMAIN
DISPLACED N/NW OF EFFECTIVE WARM SECTOR...RESULTING IN ONLY MARGINAL
TO WEAK VERTICAL SHEAR. THUS...EXPECT THE DEVELOPMENT OF PULSE
AND/OR MULTICELL STORM CLUSTERS CAPABLE OF MAINLY STRONG WIND
GUSTS.
...SWRN ORE/NRN CA...
LATEST MODEL GUIDANCE SUGGESTS THAT A VORTICITY MAXIMUM WILL LIFT
NWD AROUND ERN PERIPHERY OF MID/UPPER-LEVEL LOW...RESULTING IN AN
INCREASE IN FORCING FOR ASCENT SAT AFTERNOON INTO NIGHT. AMBIENT
AIR MASS IS EXPECTED TO BECOME HOT AND RELATIVELY MOIST WITH MLCAPE
APPROACHING 1000-2000 J/KG. IT APPEARS THAT THE STRONGER MIDLEVEL
FLOW WILL REMAIN TO THE S/W OF AREA THROUGH THE DIURNAL HEATING
CYCLE...WITH AROUND 30 KT OF VERTICAL SHEAR FORECAST ACROSS
INSTABILITY AXIS. HOWEVER...GIVEN THE PRESENCE OF STEEP LAPSE RATES
AND DEEP...WELL-MIXED BOUNDARY LAYER CONDITIONS...SETUP WILL FAVOR
THE DEVELOPMENT OF SOME HAIL AND STRONG WIND GUSTS THROUGH SAT
EVENING.
..MEAD.. 07/31/2009
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