SWODY1
SPC AC 050450
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1150 PM CDT SAT OCT 04 2008
VALID 051200Z - 061200Z
...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS SRN HIGH PLAINS INTO
NW TX AND SW OK...
...SYNOPSIS...
IN MID-UPPER LEVELS...DEEP SYNOPTIC TROUGH FCST TO CONTINUE SHIFTING
EWD ACROSS WRN CONUS. STG EMBEDDED SHORTWAVE TROUGH -- INITIALLY
EVIDENT IN MOISTURE CHANNEL IMAGERY AND VWP/RAOB DATA OVER SERN NV
AND LOWER CO RIVER REGION -- IS FCST TO MOVE ESEWD THEN EWD ACROSS
AZ/NM...REACHING SRN HIGH PLAINS BY END OF PERIOD.
MEANWHILE...WEAKER/SECONDARY SHORTWAVE TROUGH NOW OVER NRN/ERN UT
AND WRN WY WILL EJECT NNEWD ACROSS ERN WY AND ERN MT...AS NEARLY
ZONAL SPEED MAX ON BACK SIDE OF SYNOPTIC SCALE TROUGH SPREADS EWD
OVER PACIFIC NW.
AT SFC...DISCRETE LOW IS EXPECTED TO EVOLVE FROM AREA OF LEE-SIDE
TROUGHING ACROSS CENTRAL HIGH PLAINS...THEN MOVE NEWD ACROSS
SD...WITH COLD FRONT TRAILING SWWD OVER CENTRAL/ERN CO...AND WARM
FRONT LIFTING NWD ACROSS SD/IA. NEARLY OVERLAID LEE TROUGH AND
PACIFIC COLD FRONT SHOULD EXTEND SSWWD FROM ERN CO ACROSS ERN NM BY
6/00Z...MOVING EWD TO WRN KS...TX/OK PANHANDLES AND PERMIAN BASIN
REGION BY END OF PERIOD. THIS BOUNDARY MAY BE ILL-DEFINED IN SOME
AREAS BECAUSE OF CONVECTIVE PROCESSES NEARBY AND TO ITS E...OVER SRN
HIGH PLAINS.
...SRN HIGH PLAINS...PERMIAN BASIN AND LOWER PECOS VALLEY...
SCATTERED-NUMEROUS TSTMS ARE FCST ACROSS THIS REGION IN AT LEAST TWO
PRIMARY TEMPORAL REGIMES THAT MAY OVERLAP ENOUGH SPATIALLY TO COVER
ONE OUTLOOK AREA.
1. AREA OF TSTMS IS POSSIBLE EARLY IN PERIOD...PERHAPS BEGINNING
BEFORE 5/12Z...ACROSS TX PANHANDLE...MOVING EWD AND
EXPANDING/BACKBUILDING SWD DURING DAY TOWARD PROGRESSIVELY MORE
UNSTABLE SFC-BASED EFFECTIVE PARCELS WHERE AIR MASS IS MORE STRONGLY
HEATED DIABATICALLY. AS MID/UPPER TROUGH APCHS AND HEIGHT GRADIENT
ALOFT INCREASES...DEEP-LAYER SHEAR PROFILE LIKEWISE SHOULD
STRENGTHEN IN SUPPORT OF SVR POTENTIAL. BY 05/21Z...45-50 KT
EFFECTIVE SHEAR MAGNITUDES ARE POSSIBLE...SUPPORTING POTENTIAL FOR
STORM ROTATION.
HOWEVER...LIMITING FACTORS FOR SVR THREAT INVOLVE INSTABILITY AND
PROBABLE MESSY/CLUSTERED STORM MODES. WITH STRONGEST COOLING ALOFT
STILL DISPLACED W OF THIS ACTIVITY FOR MOST OR ALL
AFTERNOON...BUOYANCY WILL BE LIMITED SUBSTANTIALLY BY WEAK LAPSE
RATES...AND ALSO BY LACK OF MORE ROBUST BOUNDARY LAYER MOISTURE.
UPSTREAM BRO/CRP/DRT RAOBS FROM 5/00Z SUGGEST NWWD ADVECTION OF SFC
MOISTURE EARLY IN PERIOD MAY BE OFFSET BY VERTICAL MIXING OVER
EDWARDS PLATEAU AND LOWER PECOS VALLEY REGIONS...WITH DEW POINTS
GENERALLY 50S F IN PROSPECTIVE INFLOW REGION FOR ACTIVITY.
ACCORDINGLY MODIFIED WRF-KF SOUNDINGS YIELD MLCAPES AROUND 500-800
J/KG AWAY FROM CONVECTION...BUT ALSO WEAK MLCINH IN DISFAVOR OF
SUSTAINED DISCRETE STORM MODE.
2. SECONDARY DEVELOPMENT MAY OCCUR FARTHER W DURING MID-LATE
AFTERNOON INTO EARLY EVENING ACROSS ERN NM AND TRANS-PECOS REGION OF
W TX...MOVING EWD ACROSS SRN HIGH PLAINS AND PERMIAN BASIN DURING
EVENING AND OVERNIGHT HOURS. MUCH OF THIS ACTIVITY WOULD BE MOVING
INTO AIR MASS SEEMINGLY STABILIZED TO GREAT EXTENT BY EARLIER
ACTIVITY. HOWEVER...COMBINATION OF LOW LEVEL WAA AND MIDLEVEL
ASCENT/COOLING MAY ALLOW SUFFICIENT RECOVERY FOR ORGANIZED SVR
POTENTIAL...AMONG SHEAR PROFILES STILL SUITABLE FOR SVR.
ONE OR TWO PRIMARY AREAS OF TSTMS SHOULD MOVE EWD ACROSS CAPROCK AND
WRN LOW PLAINS OVERNIGHT...SVR POTENTIAL BECOMING MORE MRGL
OVERNIGHT AS TSTMS MOVE INTO PROGRESSIVELY LESS UNSTABLE AIR MASS.
..EDWARDS/CROSBIE.. 10/05/2008
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