SWODY2
SPC AC 071722
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1122 AM CST WED MAR 07 2012
VALID 081200Z - 091200Z
...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS CENTRAL TX TO
CENTRAL/SRN AR...
...SYNOPSIS...
SPLIT-FLOW PATTERN FCST ALOFT...RELATED TO STG SHORTWAVE TROUGH AND
EMBEDDED 500-MB CYCLONE NOW EVIDENT IN MOISTURE CHANNEL IMAGERY OVER
SRN UT/NRN AZ REGION. 12Z 500-MB ANALYSIS DEPICTED TWO INTERNAL
CENTERS WITH THAT CYCLONE...ALONG WITH NEARLY SYMMETRIC/300-M
ISALLOHYPSIC DIFFERENTIAL. AS POSITIVELY TILTED/NRN-STREAM TROUGH
NOW OVER NRN PLAINS MOVES AWAY...SWRN CONUS CYCLONE WILL
CONSOLIDATE...WHILE BECOMING MORE REMOVED FROM PREVAILING WLYS AND
MORE POSITIVELY TILTED. DURING 8/12Z-9/00Z TIME FRAME...CYCLONE
SHOULD MOVE EWD ACROSS NM. OPERATIONAL SPECTRAL/NAM AGREE WITH LOW
REACHING TX PANHANDLE BY 9/12Z. BY CONTRAST...ALL 10 WRF MEMBERS OF
7/09Z SREF SUBSTANTIALLY RETROGRADE 50-MB LOW SWWD ACROSS NM AND
INTO AZ DURING LATTER HALF OF PERIOD...STRONGLY INFLUENCING SREF
MEAN. BECAUSE THAT SREF PACKAGE DID NOT INCLUDE LATEST 12Z RAOB
DATA...THIS FCST WILL LEAN HEAVILY TOWARD OPERATIONAL MODELS.
STILL...SOME UNCERTAINTY NEEDS TO BE FACTORED INTO THIS
SCENARIO...GIVEN HISTORIC PATTERN TENDENCIES OF SUCH CYCLONES TO
STALL/RETROGRADE MORE THAN PROGGED.
SFC COLD FRONT -- NOW OVER SERN MN...SERN NEB AND SWRN KS -- IS
EXPECTED TO MOVE SEWD ACROSS MID-UPPER MS VALLEY AND UPPER GREAT
LAKES INTO EARLY DAY-2...EXTENDING SWWD INTO FRONTAL-WAVE LOW OVER
NW TX BY ABOUT 8/12Z. BY 9/00Z...EXPECT LOW TO REACH CENTRAL TO NE
TX...WITH FRONT SWWD INTO COAHUILA AND ENEWD OVER SERN OK/SWRN AR
REGION ACROSS MID TN. BY END OF PERIOD...FRONT SHOULD REACH
NC...CENTRAL/NRN AL...THROUGH FRONTAL WAVE INVOF SHV/GGG AREA...THEN
SWWD ACROSS DEEP S TX.
...CENTRAL TX TO CENTRAL/SRN AR...
SCATTERED ELEVATED TSTMS ARE FCST TO BE ONGOING AT 8/12Z ACROSS
PORTIONS OK...WITH POTENTIAL FOR OCNL HAIL...PER DAY-1 OUTLOOK.
THIS POST-FRONTAL CONVECTION WILL DEVELOP FARTHER SWD WITH TIME
DURING DAY...APACE WITH FRONTAL MOVEMENT.
MORE SUBSTANTIAL/SFC-BASED SVR POTENTIAL SHOULD DEVELOP DURING
AFTERNOON AS FRONTAL ZONE AND SFC WAVE ENCOUNTER
DESTABILIZING/MOISTENING WARM SECTOR. TSTMS ARE EXPECTED TO FORM ON
BOTH SIDES OF SFC FRONT AND INCREASE IN COVERAGE THROUGH
AFTERNOON/EVENING. OCNL SVR HAIL WILL REMAIN POSSIBLE...WITH
POTENTIAL FOR DAMAGING GUSTS PRIMARILY FROM THAT CONVECTION
ALONG/AHEAD OF FRONT. DIABATIC HEATING SHOULD DIMINISH WARM-SECTOR
CINH ENOUGH TO PERMIT AT LEAST ISOLATED TO WIDELY SCATTERED
PREFRONTAL DEVELOPMENT ALSO. SFC DEW POINTS COMMONLY MID-60S F
SHOULD OFFSET MODEST LAPSE RATES ALOFT ENOUGH TO SUPPORT MLCAPE IN
100-2000 J/KG RANGE...AMIDST 40-50 KT EFFECTIVE SHEAR MAGNITUDES.
WEAK SFC WINDS AND SECONDARY RELATIVE WEAKNESSES AROUND 2-3 KM AGL
WILL WEAKEN HODOGRAPHS...ALTHOUGH THEIR CURVATURE AND 0-1 KM
MAGNITUDES STILL SHOULD YIELD ENOUGH SRH FOR AT LEAST TRANSIENT
SUPERCELL THREAT. AS SUCH...AND WITH LOW LCL LIKELY...A FEW
TORNADOES ALSO ARE POSSIBLE. HOWEVER...THIS POTENTIAL MAY BE
MITIGATED BY LIKELIHOOD OF QUICK TRANSITION TO MESSY CONVECTIVE
MODES OF QUASI-LINEAR AND/OR CLUSTERED NATURE.
SVR PROBABILITIES DECREASE WITH NEWD EXTENT ALONG/AHEAD OF COLD
FRONT DUE TO VEERING/WEAKENING LOW-LEVEL WINDS...DECREASING
LOW-LEVEL SHEAR/CONVERGENCE...AND WEAKER BOUNDARY-LAYER THETAE. SVR
PROBABILITIES ALSO WILL DIMINISH WITH TIME AND SEWD EXTENT OVERNIGHT
AS PROGRESSIVE/ANAFRONTAL REGIME IMPINGES ON NOCTURNALLY COOLING AIR
MASS...WITH BULK OF CONVECTION FCST TO BE ELEVATED AND BEHIND SFC
BOUNDARY.
..EDWARDS.. 03/07/2012
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