SPC AC 051233
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0733 AM CDT FRI JUN 05 2009
VALID 051300Z - 061200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER THE CENTRAL/SRN HIGH
PLAINS EWD INTO THE CENTRAL PLAINS...
...CENTRAL HIGH PLAINS...
INCREASING SWLY MID/UPPER LEVEL FLOW WILL CONTINUE TO OVERSPREAD THE
CENTRAL ROCKIES AND ADJACENT HIGH PLAINS TODAY AHEAD OF UPPER LOW
EJECTING ACROSS THE GREAT BASIN. MODELS SUGGEST SURFACE LOW
PRESSURE CENTER WILL DEVELOP OVER NERN CO DURING THE AFTERNOON WITH
STRONG HEATING INTO CENTRAL/SERN CO SHIFTING DRY LINE/LEE TROUGH EWD
NEAR THE KS BORDER. BOUNDARY LAYER AHEAD OF DRY LINE AND
EAST-NORTHEAST OF THE LOW CENTER WILL REMAIN SUFFICIENTLY MOIST FOR
MODERATE INSTABILITY BY THE MID AFTERNOON...AS TEMPERATURES WARM
INTO THE 70S F AND DEW POINTS HOLD IN THE LOWER 50S F.
THUNDERSTORMS ARE EXPECTED TO DEVELOP WITHIN DEEP UPSLOPE REGIME AND
OVER HIGHER TERRAIN FROM CENTRAL CO INTO ERN WY BY THE MID TO LATE
AFTERNOON. THIS ACTIVITY WILL LIKELY EVOLVE INTO SUPERCELLS AND
ORGANIZED CLUSTERS AS IT OVERSPREADS INSTABILITY AXIS OVER THE HIGH
PLAINS THROUGH THE EVENING...GIVEN EFFECTIVE SHEAR IN EXCESS OF 50
KT. IN ADDITION TO LARGE HAIL /SOME OF WHICH COULD BE QUITE
LARGE/...A FEW TORNADOES ARE EXPECTED WITH ANY LONGER-LIVED
SUPERCELL ACROSS NERN CO/ERN WY/WRN NEB...ESPECIALLY INTO THE EARLY
EVENING AS LOW LEVEL HODOGRAPHS ENLARGE DUE TO STRENGTHENING
NOCTURNAL SSELY LLJ. ACTIVITY WILL LIKELY BUILD UPSCALE INTO A MCS
DURING THE MID TO LATE EVENING WITH ADDITIONAL ELEVATED DEVELOPMENT
OCCURRING OVERNIGHT ALONG NOSE OF 50+ KT LLJ WHICH WILL LIKELY
MAINTAIN A RISK OF LARGE HAIL AND ISOLATED DAMAGING WINDS EWD OVER
THE CENTRAL PLAINS.
...SRN HIGH PLAINS...
STRONG HEATING ALONG THE DRYLINE WILL ONCE AGAIN ASSIST ISOLATED
THUNDERSTORM DEVELOPMENT SWD INTO THE TX SOUTH PLAINS. BOUNDARY
LAYER AIRMASS IS GRADUALLY MOISTENING ACROSS THIS REGION AS SFC
ANTICYCLONE SHIFTS EAST ACROSS TX. ALTHOUGH SHEAR PROFILES WILL NOT
BE THAT STRONG...IT APPEARS DEEP LAYER SHEAR WILL BE MORE THAN
ADEQUATE FOR A FEW ORGANIZED MULTI-CELL THUNDERSTORMS...OR PERHAPS
AN ISOLATED SLOW MOVING SUPERCELL. LARGE HAIL AND DAMAGING WINDS
ARE THE PRIMARY THREATS.
...WRN WY TO ERN ORE...
UPPER TROUGH WILL BECOME ORIENTED ALONG AN AXIS FROM SWRN MT TO
CNTRL CA BY EARLY EVENING...WHILE QUITE COLD MID LEVEL
TEMPERATURES...H5 TO -18C...SETTLE INTO THE GREAT BASIN BENEATH THIS
FEATURE. STRONG MID LEVEL FLOW EJECTING ACROSS UT WILL ALLOW A
RATHER PRONOUNCED DRY SLOT TO SURGE ACROSS THE GREAT BASIN
INTO UT. GREATER MOISTURE PLUME CHARACTERIZED BY PW VALUES ON THE
ORDER OF 0.75 INCHES WILL HOLD ACROSS MUCH OF WRN WY/ID INTO ERN
ORE...WELL REMOVED FROM STRONGER SWLY FLOW REGIME. SCATTERED
THUNDERSTORMS SHOULD EASILY DEVELOP WITHIN THIS MOIST
ENVIRONMENT...POSSIBLY INITIATING AS EARLY AS 18Z. ISOLATED LARGE
HAIL AND GUSTY WINDS ARE THE PRIMARY THREATS. AT THIS TIME IT
APPEARS AIRMASS OVER UT WILL DRY TOO QUICKLY AND REMAIN TOO STABLE
TO SUPPORT ANY MEANINGFUL THREAT FOR ORGANIZED SEVERE THUNDERSTORMS
INTO THE GREAT BASIN.
...SOUTHEAST...
WEAKENING UPPER LOW WILL PERSIST OVER THE SOUTHEAST TODAY WITH
ASSOCIATED AXIS OF MODEST SWLY LOW TO MID LEVEL WINDS. PROFILES
WILL REMAIN VERY MOIST AND ONLY MARGINALLY TO MODERATELY UNSTABLE...
HOWEVER APPEARS AN ISOLATED STRONG/DAMAGING WIND GUST REMAINS
POSSIBLE WITH STRONGER STORMS INTO THE EARLY EVENING.
..EVANS/HURLBUT.. 06/05/2009
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
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