SWODY2
SPC AC 310547
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1247 AM CDT WED MAR 31 2010
VALID 011200Z - 021200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
MID-UPPER HEIGHTS CONTINUE TO FALL OVER WRN CONUS AND RISE OVER MOST
OF ERN STATES...AS MID-UPPER CYCLONE MOVES OFFSHORE MID-ATLANTIC/SRN
NEW ENGLAND REGION...AND SERIES OF SHORTWAVE TROUGHS AFFECT W COAST
STATES. MOST IMPORTANT OF THESE PERTURBATIONS WILL BE SHORTWAVE
TROUGH -- NOW EVIDENT IN MOISTURE CHANNEL IMAGERY INVOF 41N138W. AS
THIS FEATURE MOVES TOWARD MEAN TROUGH...IT WILL AMPLIFY
CONSIDERABLY. THIS TROUGH THEN SHOULD TURN EWD AND MOVE FROM
POSITION OVER SRN CA AND NRN BAJA AROUND 1/12Z TO NM AND INTERIOR
NWRN MEX BY 2/12Z...AS PART OF REGIME OF HIGH-AMPLITUDE TROUGHING
EXTENDING NNEWD ACROSS DAKOTAS. AHEAD OF THAT...AND DURING LATTER
HALF OF PERIOD...120-140 KT/SSWLY 250 MB SPEED MAX WILL TRANSLATE
EWD ACROSS NRN/CENTRAL PLAINS AND CENTRAL/SRN HIGH PLAINS.
VIGOROUS LEE-SIDE TROUGHING AND FRONTOGENESIS IN LOW-LEVELS SHOULD
RESULT IN 1/12Z SFC CYCLONE OVER NWRN CO WITH QUASISTATIONARY
FRONTAL ZONE CURVING EWD/NEWD OVER NEB TO SRN MN. BY 2/00Z...LOW
SHOULD RESIDE OVER CENTRAL/SWRN NEB AT INFLECTION POINT IN FRONTAL
ZONE. FRONT SHOULD EXTEND SSWWD ACROSS WRN TX PANHANDLE AND SERN
NM...MOVING SLOWLY EWD OVERNIGHT ACROSS WRN KS...AND INTO WRN OK AND
NW TX. DRYLINE WILL BECOME BETTER-DEFINED WITH TIME FROM
W-CENTRAL/SWRN KS SWWD ACROSS W-CENTRAL/SW TX...AS BROAD SWATH OF
PARTIALLY MODIFIED RETURN-FLOW AIR ADVECTS MOISTURE POLEWARD THROUGH
WARM SECTOR.
...CENTRAL/SRN PLAINS...
SFC ANALYSIS SHOWS SUFFICIENT MARINE MODIFICATION HAS OCCURRED TO
YIELD BROAD FIELD OF 60-64 F SFC DEW POINTS OVER ROUGHLY SWRN 1/3 OF
GULF...WITH 50S F ASHORE ENTIRE TX COASTAL PLAIN. MODIFIED 31/00Z
RAOBS AROUND GULF INDICATE MARINE BOUNDARY LAYER IS RELATIVELY
SHALLOW AND MAY BE EASILY MIXED WHERE STG DIABATIC HEATING DOES TAKE
PLACE...AT LEAST TO EXTENT THAT STG CAPPING WILL PERMIT. MIXING AND
RELATED BOUNDARY LAYER DESTABILIZATION COULD BE RESTRICTED DIURNALLY
DUE TO LOW CLOUDS COVERING MUCH OF MOIST SECTOR...ALTHOUGH NARROW
CORRIDOR AHEAD OF FRONT/DRYLINE SHOULD CLEAR LONG ENOUGH FOR AT
LEAST A FEW HOURS OF STG HEATING. EXPECT PLUME OF LOW-50S TO
LOW-60S F SFC DEW POINTS BY 2/00Z FROM N-CENTRAL/NW TX TO N-CENTRAL
KS.
SEVERAL DAYS OF PRIOR SWLY FLOW ALOFT WILL HAVE YIELDED STOUT
ELEVATED MIXED-LAYER AIR MASS CHARACTERIZED BY STEEP MIDLEVEL LAPSE
RATES...BUT ALSO STG CAPPING OF BOUNDARY LAYER BENEATH. THIS SHOULD
PRECLUDE AFTERNOON TSTMS OVER MOST OF OUTLOOK AREA...ALTHOUGH
DEEP-LAYER SHEAR PROFILES WILL SUPPORT CONDITIONAL SVR POTENTIAL
WITH ANY TSTM THAT CAN DEVELOP. IF AN ISOLATED DIURNAL TSTM CAN
FORM...PRIND PROBABILITY WOULD BE RELATIVELY MAXIMIZED BY LATE
AFTERNOON OVER N-CENTRAL OR W-CENTRAL KS -- NEAR COLD FRONT/DRYLINE
INTERSECTION AND IN RELATIVE PROXIMITY TO RELATIVE LOW-LEVEL
CONVERGENCE MAX REPRESENTED BY SFC CYCLONE. THREAT IS TOO
CONDITIONAL/ISOLATED FOR CATEGORICAL OUTLOOK ATTM.
MAIN CONVECTIVE POTENTIAL..AND CONDITIONAL SVR THREAT...WILL BE NEAR
END OF PERIOD IN CORRIDOR FROM N-CENTRAL KS TO WRN OK AND NW AND
W-CENTRAL TX. AS TIME PROGRESSES AFTER 2/06Z...PROBABILITY WILL
INCREASE FOR LINE OF TSTMS TO DEVELOP ALONG KS/OK SEGMENT OF COLD
FRONT SSWWD TOWARD AND PERHAPS ALONG DRYLINE. QUESTION ATTM IS NOT
SO MUCH WHETHER THIS WILL OCCUR...BUT INSTEAD...TO WHAT EXTENT
BEFORE VERSUS AFTER 2/12Z. TIMING WILL DEPEND ON MESOSCALE FACTORS
SUCH AS STRENGTH OF FRONTOGENETIC FORCING AND CONVECTIVE-SCALE
LIFT...IN ENVIRONMENT WHERE FLOW BACKING WITH HEIGHT IN 800-600 MB
LAYER INDICATES LIKELIHOOD THAT LINEAR MODE WOULD BECOME DOMINANT
FAIRLY QUICKLY AFTER INITIATION. SOME SUBSET OF THIS CORRIDOR MAY
BE UPGRADED CATEGORICALLY IF CONFIDENCE INCREASES IN A FEW HOURS OF
ORGANIZED CONVECTION BEFORE 12Z...GIVEN STRENGTH OF DEEP-LAYER WIND
FIELDS.
..EDWARDS.. 03/31/2010
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