SWODY1
SPC AC 192000
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0300 PM CDT THU MAY 19 2011
VALID 192000Z - 201200Z
...THERE IS A MDT RISK OF SVR TSTMS ACROSS CENTRAL KANSAS AND A
PORTION OF NORTHWEST AND WESTERN OKLAHOMA...
...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK AREA
FROM WEST TX TO SRN NEB...
...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE NORTHEAST
FROM SERN NY AND ERN PA AND NJ TO DELMARVA...
...OK/KS...
INTENSE SUPERCELL DEVELOPMENT ALONG THE DRYLINE IN WRN OK OVER THE
PAST TWO HOURS...AND HIGHER CONFIDENCE IN SIGNIFICANT SEVERE STORMS
ACROSS CENTRAL KS THIS AFTERNOON HAVE RESULTED IN AN INCREASE IN
HAIL AND TORNADO PROBABILITIES ACROSS THESE AREAS...AND THE
INTRODUCTION OF A MDT RISK OF SEVERE STORMS THIS AFTERNOON AND
TONIGHT.
SUPERCELLS IN OK WILL CONTINUE TO POSE A VERY LARGE HAIL THREAT AS
WELL AS SOME TORNADO POTENTIAL AS THEY TRACK NNEWD ACROSS WRN
PORTIONS OF THE STATE THROUGH THE AFTERNOON. MEANWHILE...A MORE
VOLATILE ENVIRONMENT APPEARS TO BE DEVELOPING NEAR TRIPLE-POINT LOW
INVOF WRN AND CNTRL KS. STORM INITIATION APPEARS IMMINENT ALONG THE
WARM FRONT TO THE WEST OF ICT TO HLC. AIRMASS DESTABILIZATION
CONTINUES ACROSS THIS AREA AND SHOULD FUEL INTENSE STORM UPDRAFTS.
LOCALLY BACKED LOW LEVEL FLOW TOPPED BY CLASSIC DIFFLUENT EXIT
REGION OF MID/UPPER JET WILL SUPPORT SUPERCELLS GIVEN EFFECTIVE
DEEP-LAYER SHEAR OF 40-60KT. IN ADDITION TO VERY LARGE
HAIL...EFFECTIVE SRH ON THE ORDER OF 200 M2/S2 ALONG THE WARM FRONT
SHOULD ALSO SUPPORT THE POTENTIAL FOR A COUPLE TO A FEW STRONG
TORNADOES. GIVEN THE SUPPORTIVE INGREDIENTS IN PLACE...BUT STILL
SOME QUESTIONS ABOUT STORM EVOLUTION/COVERAGE...SUFFICIENT
CONFIDENCE EXISTS FOR AN UPGRADE TO MDT RISK WITH THIS OUTLOOK.
..CARBIN.. 05/19/2011
.PREV DISCUSSION... /ISSUED 1122 AM CDT THU MAY 19 2011/
...CENTRAL/SOUTHERN PLAINS...
SATELLITE IMAGERY THE PAST 6 HOURS SHOWS THE UPPER WINDS HAVE
STARTED TO BACK ACROSS THE SRN/CENTRAL HIGH PLAINS...IN RESPONSE TO
ONE SHORTWAVE TROUGH LIFTING NWWD FROM THE CENTRAL PLAINS TOWARD THE
NRN ROCKIES...AND AN IMPRESSIVE SHORTWAVE TROUGH MOVING ESEWD
THROUGH SRN CA TOWARD AZ. THIS SHOULD RESULT IN THE DRYLINE TO NOT
MIXING AS FAR EAST AS WED...PERHAPS ONLY TO NEAR A DDC-GAG-ABI LINE
BY LATE AFTERNOON. WV IMAGERY SUGGESTS A WEAK WAVE IS MOVING INTO
WRN NM AND PRIMARY LIFT WILL SPREAD TOWARD ERN CO/WRN KS LATE IN THE
DAY...BUT THE DYNAMICAL FORCING SHOULD BE WEAK OVER MOST OF THE
WARM SECTOR. MOST MODELS...INCLUDING THE HIGH RESOLUTION
VERSIONS...ARE CONSISTENT IN STORMS DEVELOPING 21-00Z IN AREA OF
STRONGER LOW LEVEL CONVERGENCE NEAR INTERSECTION OF DRYLINE AND WARM
FRONT IN CENTRAL KS. THE APPROACHING WAVE MAY ALSO AID STORM
DEVELOPMENT SWD ALONG DRYLINE INTO NWRN OK. MODERATE INSTABILITY AND
DEEP LAYER SHEAR AT 50-60 KT WILL FAVOR SUPERCELLS. THIS COMBINATION
OF SHEAR AND INSTABILITY SHOULD SUPPORT HAIL IN EXCESS OF 2
INCHES...WIND DAMAGE AND TORNADOES...ESPECIALLY CLOSER TO THE WARM
FRONT IN KS.
...SWRN OK SWWD INTO SWRN TX...
DRYLINE WILL RETREAT WWD DURING THE NIGHT AND MAY PROVIDE FOCUS FOR
THUNDERSTORMS TO DEVELOP...AFTER 06Z...AS LARGE SCALE FORCING
INCREASES FROM THE WEST. THE COMBINATION OF DEWPOINTS CLIMBING BACK
INTO THE MID 60S...STEEP MID LEVEL LAPSE RATES AND MID LEVEL SPEED
MAX AT 50 KT WILL PROVIDE SUFFICIENT SHEAR AND INSTABILITY FOR
SUPERCELLS. GIVEN THE TIME OF NIGHT AND SLIGHTLY STABLE BOUNDARY
LAYER...EXPECT SEVERE HAIL TO BE THE MAIN THREAT... THOUGH STRONG
DOWNDRAFTS MAY ALSO RESULT IN WIND DAMAGE.
...MID ATLANTIC STATES INTO SOUTHERN NEW ENGLAND...
THE UPPER LOW IS CURRENTLY LOCATED OVER FAR NRN WV AND IS FORECAST
TO SHIFT EWD ACROSS NRN MD THROUGH THE DAY. AT MID MORNING...WV
IMAGERY SHOWS AN IMPRESSIVE SHORTWAVE MOVING NEWD AROUND UPPER LOW
FROM NRN VA TOWARD ERN PA/NJ. CONVECTION HAS RECENTLY DEVELOPED
AHEAD OF THIS FEATURE IN ERN PA AND SHOULD MOVE/SPREAD NWD THROUGH
THE DAY ACROSS ERN PA/NJ AND NY. ALTHOUGH INSTABILITY IS NOT
PARTICULARLY STRONG...SOME WARMING HAS RESULTED IN MLCAPES TO AROUND
500 J/KG. THIS INSTABILITY COMBINED WITH DEEP LAYER SHEAR AROUND 30
KT AND MID LEVEL LAPSE RATES BETWEEN 6.5-7.0 C/KM FAVOR MULTICELL
STORMS WITH HAIL AND STRONG GUSTY WINDS.
ANOTHER IMPULSE WAS LOCATED NEAR THE KY/WV BORDER AND ALL MODELS ARE
SUGGESTIVE OF CONVECTION DEVELOPING LATER THIS AFTERNOON IN THE
DELMARVA AREA WITH THIS SYSTEM. STORMS THAT DEVELOP WILL BE
WITHIN A SLOWLY DRYING BOUNDARY LAYER AND WHEN COMBINED WITH WLY
WINDS ALOFT AND STEEPENING LOW LEVEL LAPSE RATES...STRONG AND
POSSIBLY SEVERE WIND GUSTS ARE POSSIBLE.
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