SWODY2
SPC AC 281711
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1111 AM CST TUE DEC 28 2010
VALID 291200Z - 301200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
STG HEIGHT FALLS ALOFT ARE FCST OVER ROCKY MOUNTAIN STATES AND GREAT
BASIN DURING THIS PERIOD. BY 30/12Z...SERIES OF SPEED/VORTICITY
MAXIMA -- NOW MOVING AROUND SRN/WRN SIDES OF MID-UPPER LEVEL LOW
OVER GULF OF AK -- WILL HAVE CROSSED PAC NW AND EVOLVED INTO DEEP
TROUGH FROM NRN ROCKIES SWD ACROSS GREAT BASIN TO NWRN MEX. MOST
WRF/SPECTRAL MEMBERS OF SREF FCST CLOSED 500-MB CYCLONE OVER NRN
ROCKIES BY END OF PERIOD...ANCHORING THAT TROUGH. SEPARATE/WEAKER
TROUGH -- NOW EVIDENT IN UPPER AIR ANALYSES AND MOISTURE CHANNEL
IMAGERY FROM SWRN KS SWWD ACROSS S-CENTRAL BAJA -- IS FCST TO WEAKEN
AND PIVOT NEWD...EFFECTIVELY DIVIDING INTO TWO PRIMARY VORTICITY
MAXIMA BY END OF PERIOD...SRN ONE CROSSING NWRN GULF TO REACH LOWER
DELTA REGION.
AT SFC...LOW OVER NRN ROCKIES AT 29/12Z IS FCST TO MOVE ESEWD ACROSS
WY...CONSOLIDATING LATE IN PERIOD WITH INITIALLY SEPARATE REGIME OF
CYCLOGENESIS OVER CENTRAL HIGH PLAINS. BY 30/12Z...EXPECT PRIMARY
SFC LOW OVER KS/NEB BORDER REGION BETWEEN HLC-LNK. THIS LOW WILL BE
ATTACHED TO COLD FRONT EXTENDING WWD ACROSS NERN CO. BY THAT
TIME...STRENGTHENING BRANCH OF SFC FRONTAL ZONE...MOVING SLOWLY
EWD...WILL EXTEND NNEWD FROM LOW OVER ERN SD AND NWRN MN.
...W GULF COASTAL PLAIN...
CONVECTION MAY BE ONGOING AT BEGINNING OF PERIOD IN REGIME OF
STG/ELEVATED WAA BUT WEAK BUOYANCY...ACROSS PORTIONS N-CENTRAL TX
INTO ARKLATEX REGION. THIS ACTIVITY SHOULD MOVE NEWD INTO WEAKER
INSTABILITY AND DIMINISH THROUGH PERIOD...HOWEVER EMBEDDED THUNDER
MAY OCCUR AS FAR NE AS PORTIONS LOWER OH VALLEY. MORE CONDITIONAL
CONVECTIVE POTENTIAL EXISTS EARLY IN PERIOD OVER S-CENTRAL
TX...WHERE CINH WILL BE STRONGER...BUT ALSO VERTICAL SHEAR WILL BE
FAVORABLE. EWD EXTENSION OF THIS REGIME AND/OR ADDITIONAL TSTM
DEVELOPMENT IS EXPECTED OVER PORTIONS SE TX DURING DAY WITH AT LEAST
MRGL WIND/TORNADO THREAT. ACTIVITY THEN SHOULD SHIFT ENEWD INTO
REGIME OF MUCH WEAKER INSTABILITY OVER LA/MS DURING EVENING.
SFC BOUNDARIES WILL BE SUBTLE...LARGELY RELATED TO LAND/SEA THERMAL
GRADIENT AND AREAS OF DIFFERENTIAL DIURNAL HEATING INLAND. BROADLY
CONFLUENT BOUNDARY-LAYER FLOW IS EXPECTED ACROSS PORTIONS MID-UPPER
TX COASTAL PLAIN AND E TX DURING AFTERNOON...AMIDST WEAK CINH.
MIDLEVEL DCVA PRECEDING SRN-STREAM TROUGH WILL PASS OVER THIS REGION
ALSO. ASSOCIATED ENHANCEMENT OF MIDLEVEL LAPSE RATES WILL BE
JUXTAPOSED WITH ONGOING WAA REGIME AND NEAR-SATURATED SFC CONDITIONS
INLAND TO YIELD SFC-BASED BUOYANCY...DESPITE INCOMPLETELY MODIFIED
RETURN-FLOW AIR WITH RELATIVELY COOL TEMPS IN 60S F INLAND TO LOW
70S COAST. MODIFIED FCST SOUNDINGS SHOW MLCAPE 1000-1500 J/KG
OFFSHORE...DECREASING BELOW 300 J/KG OVER NE TX IN AREAS STABILIZED
BY CLOUDS/PRECIP. DEEP-LAYER SHEAR MAY SUPPORT ORGANIZED CLUSTERS
OF TSTMS...WITH POCKETS OF ENHANCED SRH SUITABLE FOR STORM ROTATION
ALSO POSSIBLE. ATTM THREAT APPEARS TOO CONDITIONAL/ISOLATED TO
WARRANT CATEGORICAL OUTLOOK...THOUGH IT MAY BE CONCENTRATED FURTHER
BY MESOSCALE FOCI.
..EDWARDS.. 12/28/2010
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