SPC AC 131254
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0754 AM CDT SUN JUN 13 2010
VALID 131300Z - 141200Z
...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO EARLY
TONIGHT FROM THE SRN HIGH PLAINS TO THE MID MS VALLEY...
...SRN HIGH PLAINS TO MID MS VALLEY THROUGH TONIGHT...
THE CLOSED LOW CENTERED OVER UT WILL DRIFT EWD THROUGH EARLY MONDAY
AND BEGIN TO EVOLVE INTO MORE OF AN OPEN WAVE...AS EMBEDDED SPEED
MAXIMA EJECT NEWD TO THE CENTRAL PLAINS. AN ASSOCIATED SURFACE
FRONT WILL MOVE SLOWLY SEWD ACROSS SRN IA/NEB...KS...AND THE TX
PANHANDLE. THE SURFACE PATTERN HAS BEEN COMPLICATED BY OUTFLOW FROM
OVERNIGHT CONVECTION...WITH THE EFFECTIVE FRONT NOW EXTENDING FROM
NW MO TO S/SE KS AND NW OK. ONGOING CONVECTION SHOULD CONTINUE TO
REINFORCE THE COLD POOL/OUTFLOW BOUNDARY... WHICH WILL PROVIDE A
FOCUS FOR ADDITIONAL THUNDERSTORM DEVELOPMENT LATER TODAY. OTHER
MORE ISOLATED STRONG/SEVERE STORMS ARE EXPECTED ALONG THE DRYLINE
INTO W TX.
BOUNDARY LAYER DEWPOINTS IN THE UPPER 60S TO LOWER 70S PERSIST
ACROSS THE WARM SECTOR THIS MORNING TO THE SE OF THE OUTFLOW/
FRONT...BENEATH MIDLEVEL LAPSE RATES NEAR 7 C/KM. DAYTIME HEATING
IN THE WARM SECTOR WILL RESULT IN AFTERNOON MLCAPE VALUES OF
2000-3000 J/KG...AND THIS INSTABILITY WILL AGAIN BE FAVORABLE FOR
SEVERE STORMS CAPABLE OF PRODUCING DAMAGING WINDS AND LARGE HAIL.
DEEP-LAYER VERTICAL SHEAR WILL BE SUFFICIENT FOR SUPERCELLS IN A
RELATIVELY NARROW CORRIDOR NEAR THE FRONT/OUTFLOW...ON THE ERN
FRINGE OF THE 30-50 KT SWLY MIDLEVEL FLOW. THE GREATER PROBABILITY
FOR SUPERCELLS WITH A COUPLE OF TORNADOES WILL BE WITH STORMS MOVING
ALONG THE SURFACE BOUNDARY WHERE LOW-LEVEL SHEAR WILL BE
MAXIMIZED...AND TEMPERATURE-DEWPOINTS SPREADS WILL BE LOWER. THE
INITIAL AFTERNOON SUPERCELLS SHOULD BEGIN TO GROW UPSCALE INTO ONE
OR MORE THUNDERSTORM CLUSTERS THAT WILL SPREAD NEWD FROM THE TX
PANHANDLE ACROSS NW/N CENTRAL OK INTO CENTRAL AND ERN KS WITH SOME
RISK FOR DAMAGING WINDS AND HAIL.
FARTHER E INTO MO/IL...SOME FORM OF THE ONGOING CLUSTERS WILL
CONTINUE EWD FROM NRN MO/SRN IA INTO IL TODAY. VERTICAL SHEAR WILL
REMAIN RELATIVELY WEAK OVER THIS AREA...BUT MODERATE INSTABILITY
WILL SUPPORT A RISK FOR DAMAGING DOWNBURST WINDS AND MARGINALLY
SEVERE HAIL WITH THE STRONGEST EMBEDDED STORMS.
...MID ATLANTIC REGION THIS AFTERNOON...
ONE WEAK MIDLEVEL TROUGH WILL EXIT THE TIDEWATER REGION THIS MORNING
WHILE AN UPSTREAM TROUGH OVER OH/KY PROGRESSES ESEWD TO VA/NC THIS
AFTERNOON. THE ARRIVAL OF THIS WAVE WILL BE PHASED WITH THE DIURNAL
CYCLE AND A WEAK SURFACE TROUGH...SUCH THAT SCATTERED THUNDERSTORM
DEVELOPMENT IS EXPECTED BY EARLY-MID AFTERNOON FROM ERN PA SWD
ACROSS VA TO CENTRAL NC. THE STORMS WILL THEN MOVE ESEWD TO THE
COAST BY THIS EVENING. THOUGH VERTICAL SHEAR AND MIDLEVEL LAPSE
RATES WILL BE RATHER WEAK...INSTABILITY SHOULD BE SUFFICIENT FOR
ISOLATED STRONG/DAMAGING DOWNBURST WINDS THIS AFTERNOON.
..THOMPSON/SMITH.. 06/13/2010
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
|
