SWODY1
SPC AC 221958
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0258 PM CDT FRI OCT 22 2010
VALID 222000Z - 231200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN AND
CENTRAL PLAINS INTO NERN CO...
...NWRN TX TO ERN TX PANHANDLE/WRN OK...
THE SLIGHT RISK HAS BEEN EXPANDED A LITTLE FARTHER WWD ACROSS NWRN
TX AND THE ERN TX PANHANDLE. A MORE SUBSTANTIAL SHORTWAVE TROUGH
HAS MOVED NWD INTO KS THIS AFTERNOON...WITH WATER VAPOR IMAGERY
SHOWING RATHER FLAT RIDGING ACROSS THIS REGION. HOWEVER...AN
APPARENT MIDLEVEL SPEED MAX IS APPROACHING W/NW TX AT THIS TIME PER
WATER VAPOR IMAGERY AND OBJECTIVE ANALYSES. FORCING FOR ASCENT WITH
THIS FEATURE MAY BE ABLE TO COMPENSATE FOR LIMITED SURFACE
HEATING/DESTABILIZATION ACROSS NW TX/ERN TX PANHANDLE INTO PARTS OF
WRN/SRN OK INTO THE EVENING. FOR ADDITIONAL NEAR TERM GUIDANCE ON
THIS AREA...PLEASE SEE MCD 1965.
...NERN CO/NWRN KS...
STEEP LAPSE RATE ENVIRONMENT...OWING TO BOTH SURFACE HEATING AND
COLD MIDLEVEL TEMPERATURES /-16 TO -18 C AT H5/ ATTENDANT TO CLOSED
LOW...FORCING FOR ASCENT WITHIN EXIT REGION OF 50 KT SLY MIDLEVEL
JET OVER WRN KS...AND CONVERGENCE ALONG SEVERAL BOUNDARIES WILL
SUPPORT ADDITIONAL TSTM DEVELOPMENT THIS AFTERNOON. GIVEN THE
POTENTIAL FOR A TORNADO AND/OR LANDSPOUT DUE TO ENHANCED LOW LEVEL
VORTICITY BENEATH THE CLOSED LOW AND AN ISOLATED HAIL THREAT...THE
SLIGHT RISK AREA HAS BEEN EXPANDED WWD INTO NERN CO. WEAK
INSTABILITY WILL TEND TO LIMIT OVERALL SEVERE COVERAGE...SUGGESTING
THIS PORTION OF THE SLIGHT TO BE CONDITIONAL AS COMPARED TO AREAS
FARTHER SOUTH OVER THE SRN PLAINS.
..PETERS.. 10/22/2010
.PREV DISCUSSION... /ISSUED 1118 AM CDT FRI OCT 22 2010/
...CNTRL/SRN PLAINS...
A COMPLEX WEATHER SCENARIO IS UNFOLDING TODAY OWING TO THE EARLY
NNEWD PROGRESSION OF STRONG MIDLEVEL VORTICITY MAXIMUM THROUGH THE
SRN INTO CNTRL HIGH PLAINS...AWAY FROM A MORE MOIST AND UNSTABLE
BOUNDARY LAYER RESIDING S OF THE RED RIVER IN TX. FORCING FOR
ASCENT ATTENDANT TO THIS MIDLEVEL FEATURE WILL LIKELY SUPPORT THE
NWD/NEWD DEVELOPMENT OF TSTMS TODAY FROM CNTRL OK INTO CNTRL/ERN KS
WHERE ISOLATED OCCURRENCES OF MAINLY HAIL WILL BE POSSIBLE.
MORNING VISIBLE SATELLITE IMAGERY AND 12Z MESOSCALE MODEL GUIDANCE
SUGGEST THAT A CORRIDOR OF STRONGER DIABATIC HEATING AND RESULTANT
DESTABILIZATION /I.E. MLCAPE APPROACHING 500-1500 J PER KG/ MAY
DEVELOP BY AFTERNOON WITHIN MIDLEVEL DRY SLOT AND ALONG WRN EDGE OF
MORE PERSISTENT TSTM ACTIVITY FROM PARTS OF WRN KS SWD INTO THE ERN
TX PNHDL/WRN OK. WHILE LARGE-SCALE FORCING FOR ASCENT WILL TEND TO
RAPIDLY DIMINISH THROUGH THE PEAK OF THE DIURNAL HEATING /ESPECIALLY
OVER THE TX PNHDL INTO WRN OK/...SUSTAINED CONVERGENCE ALONG THE
PACIFIC FRONT/DRYLINE AND RESIDUAL CONVECTIVE OUTFLOW BOUNDARIES MAY
BE SUFFICIENT TO INITIATE AND SUSTAIN ISOLATED STORMS THIS AFTERNOON
INTO EVENING. FORECAST HODOGRAPHS INDICATE VERTICALLY VEERING WIND
PROFILES WITH SUFFICIENT LOW AND DEEP-LAYER SHEAR TO SUPPORT
ROTATING STORMS WITH A RISK FOR SEVERE HAIL AND PERHAPS A TORNADO OR
TWO.
A SEPARATE TSTM REGIME WILL LIKELY PERSIST TODAY INTO TONIGHT ACROSS
PORTIONS OF S-CNTRL/SERN OK INTO N-CNTRL/NERN TX INVOF SYNOPTIC WARM
FRONT CURRENTLY RETREATING NWD TOWARD THE RED RIVER. ONGOING STRONG
TSTMS E OF FSI WILL LIKELY CONTINUE TO MOVE EWD TODAY WITH LOW-LEVEL
WAA SUPPORTING PREFERENTIAL STORM DEVELOPMENT ALONG THE SRN END OF
CONVECTIVE BAND. BREAKS IN THE CLOUDS COUPLED WITH A MOISTENING
BOUNDARY LAYER WILL CONTRIBUTE TO THE DEVELOPMENT OF A MODERATELY
UNSTABLE AIR MASS /MLCAPE OF 1000-1500 J PER KG/ BY AFTERNOON WITHIN
A KINEMATIC ENVIRONMENT FEATURING 40-50 KT OF EFFECTIVE BULK SHEAR.
MOREOVER...THE SRN EXTENSION OF A 35-45 KT SLY LLJ WILL RESIDE OVER
THE AREA...RESULTING IN RELATIVELY LARGE LOW-LEVEL HODOGRAPHS WITHIN
A MOIST/LOW LCL ENVIRONMENT. AS SUCH...THE THREAT WILL EXIST FOR
ISOLATED TORNADOES IN ADDITION TO HAIL AND LOCALLY DAMAGING WIND
GUSTS.
FOR ADDITIONAL NEAR TERM GUIDANCE ON THIS AREA...PLEASE SEE MCD
1963.
OVERNIGHT...ADDITIONAL SEVERE STORMS WILL BE POSSIBLE OVER WRN
PORTIONS OF THE EDWARDS PLATEAU REGION INTO W-CNTRL TX. THIS
ACTIVITY WILL BE FORCED BY THE ARRIVAL OF NEXT UPSTREAM IMPULSE
WHICH IS FORECAST TO AMPLIFY/INTENSIFY OVER NWRN MEXICO. DESPITE
THE TIME OF DAY...THE PROXIMITY TO A MOIST...UNSTABLE AIR MASS ALONG
WWD-RETREATING DRYLINE/PACIFIC FRONT SHOULD SUPPORT VIGOROUS UPDRAFT
GROWTH WITHIN A MODERATELY SHEARED /40-50 KT THROUGH THE LOWEST 6
KM/ ENVIRONMENT WHERE A RISK FOR SEVERE HAIL AND DAMAGING WIND GUSTS
WILL EXIST INTO SATURDAY MORNING.
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