SWODY3
SPC AC 310729
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0229 AM CDT WED MAR 31 2010
VALID 021200Z - 031200Z
...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS SRN PLAINS TO ARKLATEX
REGION AND AR...
...SYNOPSIS...
BY 2/12Z...SERIES OF MID-UPPER LEVEL SHORTWAVE TROUGHS -- NOW
CONTRIBUTING TO HEIGHT FALLS OVER MUCH OF WRN CONUS -- WILL LEAD TO
HIGH-AMPLITUDE TROUGH FROM DAKOTAS SSWWD ACROSS CENTRAL HIGH
PLAINS...SRN NM AND INTERIOR NWRN MEX. ANCHORING/SRN SHORTWAVE
TROUGH SHOULD MOVE EWD TO W TX BY 3/00Z...THEN PIVOT GRADUALLY ENEWD
ACROSS CENTRAL/NRN TX AND PERHAPS ARKLATEX REGION BY END OF PERIOD.
MINOR TIMING DIFFERENCES REMAIN IN MOST SHORT-RANGE PROGS...AND
UNLIKE OPERATIONAL SPECTRAL/WRF...SOME SREF MEMBERS INDICATE CLOSED
500 MB LOW BY MIDDLE OF PERIOD OVER W TX. DESPITE THESE MESOSCALE
DIFFERENCES...GENERAL TREND IS FOR MORE PROGRESSIVE AND STRONGER
HEIGHT FALLS AT LOWER LATITUDES THAN PROGS HAVE INDICATED BEFORE.
AT SFC...COLD FRONT SHOULD EXTEND FROM MN LOW SSWWD ACROSS WRN OK
AND E-CENTRAL TX EARLY IN PERIOD...MOVING EWD AND SEWD TO NEAR WRN
WI...NWRN MO...SRN OK AND SW TX BY 3/00Z...WITH DRYLINE INTERSECTING
FRONT OVER SRN OK OR N-CENTRAL TX. BY 3/12Z...FRONT SHOULD
ACCELERATE TO LM...ERN AR AND SWRN LA/SE TX AREA AS MID-UPPER TROUGH
APCHS.
...SRN PLAINS TO ARKLATEX REGION AND AR...
WHILE NOT OPTIMAL FOR THIS TIME OF YEAR...MOISTURE RETURN BY DAY-3
SHOULD BE SUFFICIENT TO SUPPORT DEVELOPMENT OF LINE OF STG-SVR TSTMS
LATE DAY-2 INTO EARLY DAY-3 PERIOD ALONG COLD FRONT...AS THAT
BOUNDARY IMPINGES UPON MOIST SECTOR. EXPECT UPPER 50S TO MID 60S F
DEW POINTS IN PRE-STORM/PRE-FRONTAL AIR MASS ACROSS CENTRAL TX INTO
OK AND SERN KS...VERTICAL SHEAR STRENGTHENING WITH TIME EARLY IN
PERIOD AS UPPER TROUGH AND PRECEDING...NEARLY MERIDIONAL UPPER JET
MAX APCH.
ADDITIONAL DEVELOPMENT OF TSTMS...WITH DAMAGING WIND...LARGE HAIL
AND TORNADOES ALL POSSIBLE...COULD DEVELOP FARTHER S ACROSS PORTIONS
CENTRAL/NRN TX AND SRN OK DURING DAY AS COMBINATION OF LOW-LEVEL
THETAE ADVECTION AND AREAS OF DIABATIC HEATING ASSIST WITH AIR MASS
RECOVERY BEHIND MORNING ACTIVITY. SPATIAL AND TEMPORAL EXTENT OF
SUCH DESTABILIZATION IS UNCERTAIN...OTHERWISE THIS COULD BE
SIGNIFICANT SVR EVENT GIVEN STRENGTH OF DEEP-LAYER WIND FIELDS.
ANTECEDENT LOW CLOUDS MAY RENDER ONLY NARROW CORRIDOR OF STG SFC
HEATING AHEAD OF FRONT AND DRYLINE DURING AFTERNOON. VERTICAL SHEAR
WILL BE STG ENOUGH TO SUPPORT TORNADO POTENTIAL...WHICH WILL DEPEND
LARGELY ON FACTORS SUCH AS PREDOMINANCE OF DISCRETE OR SEMI-DISCRETE
STORM MODES THAT ARE TOO SMALL IN SCALE TO FCST THIS FAR IN ADVANCE.
CONVECTION SHOULD PERSIST INTO EVENING AND OVERNIGHT HOURS OVER
PORTIONS E TX...ERN OK...NWRN LA AND AR...GRADUALLY OUTRUNNING
FAVORABLE DESTABILIZATION FOR SFC-BASED EFFECTIVE INFLOW PARCELS.
SVR PROBABILITIES THEREFORE ARE SLOPED GENTLY DOWNWARD WITH EWD
EXTENT OVER OUTLOOK AREA.
..EDWARDS.. 03/31/2010
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