SWODY2
SPC AC 210600
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0100 AM CDT WED APR 21 2010
VALID 221200Z - 231200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM ERN CO/WRN KS SWD ACROSS
MUCH OF W CENTRAL TX...
...SYNOPSIS...
LARGE UPPER LOW/TROUGH INITIALLY CENTERED OVER THE SRN GREAT BASIN
WILL SHIFT EWD ACROSS THE ROCKIES TOWARD THE CENTRAL U.S. THIS
PERIOD. MEANWHILE...TROUGH OVER THE NORTHEAST U.S. WILL TAKE ON A
MORE NEGATIVE TILT WITH TIME AS IT SHIFTS EWD TOWARD/INTO THE
ATLANTIC.
AT THE SURFACE...A COLD FRONT WILL CONTINUE CROSSING THE ROCKIES
AHEAD OF THE LARGE WRN SYSTEM...WITH LEE CYCLOGENESIS PROGGED OVER
THE CENTRAL HIGH PLAINS. A WARM FRONT WILL SHIFT NWD WITH TIME
ACROSS OK/AR/KS/MO...WHILE A DRYLINE MIXES EWD ACROSS THE HIGH
PLAINS THROUGH THE DAY -- EVENTUALLY TO BE OVERTAKEN BY THE
ADVANCING COLD FRONT. THE LARGE STORM SYSTEM MOVING INTO THE
CENTRAL U.S. WILL SUPPORT A RELATIVELY WIDESPREAD/
POTENTIALLY-SIGNIFICANT SEVERE WEATHER EVENT -- WHICH COULD REQUIRE
UPGRADE TO MODERATE RISK IN LATER FORECASTS AS UNCERTAINTY
DECREASES.
...ERN CO/WRN KS SWD INTO W CENTRAL TX...
PRIMARILY ELEVATED SHOWERS AND THUNDERSTORMS SHOULD BE ONGOING
ACROSS PARTS OF KS/OK AND EWD INTO SRN MO/NRN AR EARLY...INVOF A
RETREATING WARM FRONT. LOCAL HEATING THROUGH THE MORNING MAY RESULT
IN POCKETS OF SLIGHTLY MORE FAVORABLE DESTABILIZATION INVOF THE
FRONT...WHERE DEWPOINTS NEAR 60 ARE EXPECTED. WITH MODERATE/VEERING
FLOW WITH HEIGHT...A FEW STRONGER/ISOLATED SEVERE STORMS WILL BE
POSSIBLE -- WITH EVEN A TORNADO NOT OUT OF THE QUESTION INVOF THE
WARM FRONT WHERE SELY/ESELY LOW-LEVEL WINDS SHOULD ENHANCE LOW-LEVEL
SHEAR.
THE ONGOING CONVECTION MAY PROVE TO BE A COMPLICATING FACTOR FARTHER
W...PARTICULARLY ACROSS NRN PORTIONS OF THE RISK AREA INTO KS/ERN
CO. DEGREE OF HEATING ACROSS THIS PORTION OF THE THREAT AREA WILL
AFFECT THE DEGREE OF SEVERE POTENTIAL...BUT FOR NOW WILL KEEP
HIGHEST SEVERE PROBABILITY JUST S -- ACROSS THE ERN PANHANDLES AND
WRN OK AND SWD INTO TX ALONG THE EWD-MIXING DRYLINE.
AS THE DRYLINE SHIFTS EWD DURING THE DAY...HEATING OF THE MOISTENING
/LOW 60S DEWPOINTS/ BOUNDARY LAYER AWAY FROM ONGOING
CLOUDS/PRECIPITATION ALONG WITH STEEP MID-LEVEL LAPSE RATES WILL
CONTRIBUTE TO MODERATE DESTABILIZATION...WITH WIDESPREAD 1000 TO
1500 J/KG MIXED-LAYER CAPE EXPECTED BY MID AFTERNOON.
AS MID-LEVEL HEIGHT FALLS AHEAD OF THE ADVANCING UPPER SYSTEM SPREAD
EWD...LARGE-SCALE ASCENT -- FOCUSED NEAR THE DRYLINE -- SHOULD YIELD
THE DEVELOPMENT OF SCATTERED STORMS. WITH INCREASING SWLY MID-LEVEL
FLOW SPREADING EWD THROUGH THE DAY ATOP BOUNDARY-LAYER
SLYS/SELYS...SHEAR WILL BECOME QUITE FAVORABLE FOR SUPERCELLS --
SUGGESTING RAPID ACQUISITION OF ROTATING WITHIN THE DEVELOPING
STORMS. ALONG WITH THE THREAT FOR VERY LARGE
HAIL...LOCALLY-DAMAGING WINDS AND ISOLATED TORNADOES WILL ALSO BE
POSSIBLE. IF AMPLE HEATING/DESTABILIZATION CAN OCCUR INVOF THE SERN
CO SURFACE LOW AND EWD INTO SWRN KS/NWRN OK INVOF THE WARM
FRONT...MORE FAVORABLE SELYS JUST TO THE COOL SIDE OF THE FRONT
WOULD IMPLY GREATER TORNADO POTENTIAL FROM NERN CO/WRN KS INTO NWRN
OK AND PORTIONS OF THE PANHANDLES.
THREAT SHOULD SPREAD SLOWLY EWD THROUGH THE EVENING...AFFECTING OK
AND TX INTO THE OVERNIGHT HOURS. ELEVATED STORMS AND HAIL POTENTIAL
MAY SPREAD AS FAR N AS SRN NEB...AS A NOCTURNAL LOW-LEVEL JET
DEVELOPS FUELING INCREASED CONVECTION N OF THE WARM FRONT.
..GOSS.. 04/21/2010
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