SWODY2
SPC AC 210600
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0100 AM CDT WED MAY 21 2008
VALID 221200Z - 231200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE NRN HIGH PLAINS SWD
ACROSS KS/OK/N TX...
...SYNOPSIS...
LARGE-SCALE FLOW PATTERN FEATURING AN OMEGA BLOCK OVER NOAM WILL
PERSIST THIS PERIOD...AS NERN U.S./ERN CANADA UPPER LOW MOVES SLOWLY
EWD WITH TIME WHILE THE WRN U.S. VORTEX RETROGRADES WWD. MODELS
CONTINUE TO DEPICT A SHORT-WAVE TROUGH ROTATING NWD ACROSS THE HIGH
PLAINS ON ERN FRINGE OF THE MAIN UPPER SYSTEM...WHICH IS EXPECTED TO
PLAY A ROLE IN THE DAY 2 CONVECTIVE FORECAST.
AT THE SURFACE...A FRONT WILL REMAIN QUASI-STATIONARY FROM THE
SOUTHEAST U.S. WSWWD ACROSS THE LOWER MS VALLEY...AND THEN NWWD
ACROSS THE PLAINS TO A LOW OVER ERN CO. A SECOND COLD FRONT --
EXTENDING SSWWD FROM THIS LOW -- SHOULD DRIFT SLOWLY EWD ACROSS NM
THIS PERIOD...WHILE A DRYLINE EXTENDS N-S ACROSS THE CENTRAL AND SRN
HIGH PLAINS.
...NRN HIGH PLAINS ACROSS NEB/KS/WRN OK/N TX...
WIDESPREAD/ELEVATED CONVECTION SHOULD BE ONGOING AT THE START OF THE
PERIOD...FROM ERN WY/SD/NEB SEWD INTO PARTS OF IA/MO N OF THE
QUASI-STATIONARY SURFACE FRONT WITHIN REGION OF STRONG WARM
ADVECTION/ISENTROPIC LIFT. THOUGH STORMS SHOULD DECREASE IN
COVERAGE/INTENSITY SOMEWHAT THROUGH THE DAY AS THE LOW-LEVEL JET
WEAKENS...A LOCAL THREAT FOR MARGINAL HAIL MAY PERSIST THROUGH THE
MORNING/EARLY AFTERNOON.
MEANWHILE...GULF MOISTURE WILL CONTINUE SPREADING NWWD ACROSS THE
WARM SECTOR ON SELY BOUNDARY LAYER FLOW...BENEATH STEEP MID-LEVEL
LAPSE RATES. THUS...EXPECT MODERATE DESTABILIZATION THROUGH THE
AFTERNOON -- AIDED BY STRONG HEATING. CAPPING SHOULD HINDER
WARM-SECTOR STORM DEVELOPMENT WELL INTO THE AFTERNOON...WITH INITIAL
STORM DEVELOPMENT EXPECTED FROM THE HIGH PLAINS OF ERN WY/THE NEB
PANHANDLE ESEWD JUST TO THE COOL SIDE OF THE WARM FRONT. WITH
TIME...HEATING/MIXING COMBINED WITH THE PASSAGE OF THE UPPER FEATURE
SHOULD RESULT IN AMPLE WEAKENING OF THE CAP TO ALLOW STORMS TO
DEVELOP SWD ALONG THE DRYLINE -- MOST NUMEROUS ACROSS KS AND THEN
DECREASING IN NUMBER SWD ACROSS OK AND INTO TX. WITH MIXED-LAYER
CAPE IN EXCESS OF 2000 TO 2500 J/KG EXPECTED BY LATE
AFTERNOON...STORMS SHOULD QUICKLY INCREASE IN INTENSITY -- AIDED BY
VEERING/INCREASING FLOW WITH HEIGHT. THE BEST JUXTAPOSITION OF
INSTABILITY AND SHEAR SHOULD EXIST ACROSS SWRN NEB...AND THEN SWD
ACROSS W CENTRAL KS. ACROSS THIS REGION...EXPECT SUPERCELLS CAPABLE
OF PRODUCING LARGE HAIL...DAMAGING WINDS...AND ISOLATED TORNADOES.
WHILE OVERALL COVERAGE OF THE THREAT SHOULD DIMINISH
SWD...SIGNIFICANT SEVERE POTENTIAL APPEARS POSSIBLE AT LEAST AS FAR
S AS SWRN OK.
STORMS SHOULD CONTINUE WELL INTO THE EVENING ACROSS THE WARM SECTOR
BEFORE BEGINNING TO DIMINISH OVERNIGHT. SEVERE THREAT SHOULD
CONTINUE THOUGH N OF THE WARM FRONT AS LOW-LEVEL JET
REDEVELOPS...WHERE PRIMARY THREAT SHOULD BE LARGE HAIL.
...GULF COAST REGION...
WIDESPREAD SHOWERS AND THUNDERSTORMS ARE FORECAST FROM ERN TX/LA EWD
ACROSS THE CENTRAL GULF COAST REGION...AS A SHORT-WAVE TROUGH MOVES
NEWD ACROSS E TX/THE GULF OF MEXICO AND INTO THE SERN QUARTER OF THE
CONUS. WHILE INSTABILITY WILL LOCALLY SUPPORT RELATIVELY VIGOROUS
STORMS...ONLY ISOLATED/MARGINAL SEVERE THREAT APPEARS TO EXIST GIVEN
GENERALLY WEAK WIND FIELD. GREATEST THREAT SHOULD EXIST FROM SRN LA
EWD TO THE FL PANHANDLE...AS MODEST MID-LEVEL JET ASSOCIATED WITH
THE UPPER FEATURE SHIFTS ACROSS THE NRN GULF/GULF COAST REGION.
..GOSS.. 05/21/2008
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