SPC AC 241623
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1123 AM CDT SAT MAY 24 2008
VALID 241630Z - 251200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM SRN ND/SD SWD INTO PARTS
OF KS/OK...
...THERE IS A SLGT RISK OF SVR TSTMS MUCH OF FL PENINSULA...
...NRN/CENTRAL PLAINS...
THE UNSEASONABLY LARGE WRN UPPER LOW CONTINUES...HOWEVER A
SIGNIFICANT UPPER LOW ALONG WITH A SURFACE LOW HAS BEEN EJECTED AND
WILL MOVE FROM ITS CURRENT LOCATION NERN WY NNEWD ACROSS WRN ND INTO
CANADA TONIGHT. BAND OF STRONG WINDS PROVIDING FAVORABLE SHEAR FOR
ORGANIZED THUNDERSTORMS WILL ROTATE NEWD ON THE E SIDE OF LOW FROM
CENTRAL HIGH PLAINS TO UPPER MS VALLEY LATER TONIGHT.
STABILIZATION IN THE WAKE OF THE LARGE OVERNIGHT MCS CURRENTLY OVER
LOWER MO VALLEY WILL DELAY SOME THE MOISTURE/INSTABILITY RETURN
AHEAD OF THE UPPER SYSTEM INTO THE NRN PLAINS. HOWEVER WITH THE 40KT
LLJ AND CONTINUED PRESENCE OF STEEPER MID LEVEL LAPSE RATES EXPECT
MORE THAN SUFFICIENT THERMODYNAMIC SUPPORT FOR SEVERE THUNDERSTORMS
TO BE IN PLACE BY LATER THIS AFTERNOON GIVEN THE SHEAR AND LARGE
SCALE ASCENT WITH THE UPPER SYSTEM. WITH DEWPOINTS INTO THE MID 60S
SURGING NWD THRU NEB THIS AFTERNOON MLCAPES WILL CLIMB TO AOA 2000
J/KG.
SEVERE THUNDERSTORMS WILL DEVELOP ALONG AND AHEAD OF THE COLD FRONT
MOVING EWD ACROSS CENTRAL SD/NE BY LATE AFTERNOON WITH STRONG
VEERING SHEAR PROFILES SUPPORTING SUPERCELLS. RELATIVELY
COOL...STEEP LAPSE RATES SUPPORT LARGE HAIL AS WELL AS A TORNADO
THREAT WITH ANY SUPERCELL. STORMS WILL EVOLVE INTO A MORE LINEAR
MODE AFTER DARK WITH A CONTINUED SEVERE THREAT INTO THE ERN PORTION
OF NRN PLAINS AS STRONG WIND MAX AND MID LEVEL COOLING MOVE NEWD
INTO UPPER MS VALLEY OVERNIGHT. STORMS WILL BECOME INCREASINGLY
ELEVATED EARLY TONIGHT WITH EWD EXTENT INTO UPPER MS VALLEY WITH A
DECREASING SEVERE THREAT ACROSS MN AND ERN ND.
FURTHER S ALONG THE TRAILING DRY LINE THRU CENTRAL KS/WRN OK...AIR
MASS BECOMES VERY TO EXTREMELY UNSTABLE WITH MLCAPES TO 4000 J/KG.
THE CAP WILL BE MORE OF AN ISSUE THIS AREA GIVEN WARMER MID LEVEL
TEMPS. NEVERTHELESS AT LEAST ISOLATED STORMS ARE LIKELY TO DEVELOP
SWD THRU WRN OK PRIOR TO SUNSET. WITH 30-40 KT OF DEEP LAYER SHEAR
AND GIVEN THE AMOUNT OF INSTABILITY...SUPERCELLS ARE POSSIBLE WITH
ANY STORM THAT CAN BREAK THE CAP. PRIMARY THREAT WILL BE VERY LARGE
HAIL AND ISOLATED TORNADOES. THE SOUTHERN LIMIT OF DEVELOPMENT
ALONG THE DRY LINE IS DIFFICULT TO PIN DOWN PUT CAN'T RULE OUT A
LIMITED THREAT EVEN INTO NWRN TX.
...FL...
THUNDERSTORMS THIS AFTERNOON FL PENINSULA EXPECTED TO BE MORE ACTIVE
GIVEN THE PRESENCE OF A VERY UNSTABLE AIR MASS AND THE WEAK UPPER
TROUGH PASSING THRU THE STATE. WW346 HAS BEEN ISSUED REFLECTING THE
INCREASED POTENTIAL FOR PULSE SEVERE TODAY.
...INTERIOR PAC NW...
A MOIST ELY FLOW TO THE NORTH OF UPPER LOW OVER NRN CA IS
SUFFICIENTLY UNSTABLE FOR STRONG THUNDERSTORMS THIS AFTERNOON AND
EVENING. ERN OR APPEARS TO HAVE THE GREATEST THREAT OF ISOLATED
STRONG/SEVERE STORMS THIS AFTERNOON GIVEN THE PRESENCE OF STEEP MID
LEVEL LAPSE RATES. THE NUMBER AND INTENSITY OF THE STORMS DEPENDENT
ON AMOUNT OF SURFACE HEATING THAT CAN OCCUR OVER AN AREA THIS HAS
CONSIDERABLE CLOUD COVER THIS AM. PRIMARY THREAT WITH STRONGEST
UPDRAFTS WILL BE LARGE HAIL GIVEN THE GENERALLY WEAK SHEAR
PROFILES.
...AR...
COLD POOL ASSOCIATED WITH OVERNIGHT MCS STILL WORKING SEWD ACROSS
LOWER MO VALLEY. LEADING EDGE IS MOVING THRU A GENERALLY WEAKLY
SHEARED ENVIRONMENT UNDER UPPER RIDGE. HOWEVER WITH THE PRESENCE OF
VERY MOIST/UNSTABLE AIR EWD TO MS RIVER...A FEW STRONG/SEVERE STORMS
WILL STILL BE POSSIBLE UNTIL LATER THIS AFTERNOON ALONG/AHEAD OF
SURFACE BOUNDARY.
..HALES/HURLBUT.. 05/24/2008
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z
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