SPC AC 061252
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0752 AM CDT SAT JUN 06 2009
VALID 061300Z - 071200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE SRN HIGH PLAINS INTO
THE CENTRAL PLAINS...
...CENTRAL PLAINS INTO THE SRN HIGH PLAINS...
SURFACE FRONT...REINFORCED BY FRIDAY NIGHT/S MCS ACROSS NEB...WILL
LIKELY REMAIN PRIMARY FOCUS FOR SEVERE THUNDERSTORM DEVELOPMENT THIS
AFTERNOON/OVERNIGHT. THIS FRONT SHOULD REMAIN FROM PORTIONS OF ERN
IA INTO NRN KS...AND THEN EXTEND MORE NWWD ALONG THE CENTRAL HIGH
PLAINS TODAY. CAPPING AND ONLY MODEST BOUNDARY LAYER MOISTURE FOR
EARLY JUNE ACROSS THE SRN PLAINS MAY LIMIT DIURNAL DEVELOPMENT OF
THUNDERSTORMS TODAY. HOWEVER...MODELS SUGGEST SUFFICIENT HEATING
WILL GREATLY DIMINISH INHIBITION BETWEEN 21-00Z. SHOULD STORMS
DEVELOP DURING THE DAY...SHEAR WILL BE MORE THAN ADEQUATE FOR
SUPERCELLS AS BROAD AREA OF 40-60 KT SWLY MID LEVEL FLOW PERSISTS.
LOW LEVEL SHEAR WILL ALSO REMAIN ADEQUATE FOR A THREAT OF TORNADOES
INTO THE EARLY EVENING.
LATEST GUIDANCE INDICATES MORE LIKELY SCENARIO WILL BE FOR
INCREASING STORMS OVER PARTS OF CENTRAL/NRN KS INTO FAR SRN NEB
DURING THE EVENING ALONG NOSE OF 40-50 KT SLY LLJ. THIS ACTIVITY
WILL LIKELY INCREASE INTO A SEVERE MCS...AND POSSIBLE BOWING
SYSTEM...DURING THE EVENING AS IT PROGRESSES ENEWD ALONG NOSE OF
VEERING LLJ OVERNIGHT ACROSS NRN MO/SRN IA.
FARTHER SOUTH...STRONG TO SEVERE THUNDERSTORMS WILL ONCE AGAIN
DEVELOP INVOF DRY LINE INTO WRN TX LATE TODAY. SHEAR IS MUCH WEAKER
INTO THIS REGION...ALTHOUGH DEEP LAYER SHEAR AROUND 30 KT SHOULD
STILL SUPPORT ORGANIZATION INTO HIGH-BASED CLUSTERS/LINES WITH
THREATS OF LARGE HAIL AND ISOLATED DAMAGING WINDS. OVERALL SEVERE
THREAT OVER THIS REGION IS EXPECTED TO WANE THROUGH THE MID TO LATE
EVENING.
...SERN U.S...
MORNING SOUNDINGS ACROSS FL INDICATE POTENTIAL FOR A VERY UNSTABLE
AIR MASS WHERE POCKETS OF HEATING CAN OCCUR UNDER SLOW MOVING
MID/UPPER LEVEL LOW TODAY. H5 TEMPS NEAR -12C AT TBW ARE SUPPORTING
H7-H5 LAPSE RATES NEAR 7 C/KM THIS MORNING...WITH LITTLE INHIBITION.
EXPECT CONVECTION WILL DEVELOP EARLY IN THE DAY AND BECOME
INCREASINGLY WIDESPREAD OVER MUCH OF FL...INTO SERN GA/FAR SRN SC
THROUGH THE AFTERNOON. STRONGER STORMS WILL BE CAPABLE OF ISOLATED
LARGE HAIL/DAMAGING WINDS...ALTHOUGH SEVERE THREAT MAY BE LIMITED BY
EARLY START AND EXTENSIVE CONVECTION INHIBITING AFTERNOON
HEATING/INSTABILITY.
...NRN ME...
VERY STRONG MID LEVEL JET WILL OVERSPREAD THIS REGION TODAY WITH H5
WINDS IN EXCESS OF 90KT. IN ADDITION...VERY COLD H5 TEMPERATURES
NORTH OF JET AXIS WILL CONTRIBUTE TO STEEP LAPSE RATES WITHIN
STRONGLY SHEARED WLY FLOW REGIME. EXPECT FAVORABLE LEFT EXIT REGION
OF UPPER JET WILL OVERSPREAD NRN NEW ENGLAND...COINCIDENT WITH
FRONTAL PASSAGE IN THE 00Z-03Z TIME FRAME...AND LIKELY SUPPORT
THUNDERSTORMS DESPITE WEAK INSTABILITY. AT THIS TIME IT APPEARS
BOUNDARY LAYER MOISTURE/INSTABILITY WILL BE A BIT TOO LOW TO WARRANT
MORE THAN LOW PROBABILITIES FOR HAIL AND DAMAGING WINDS.
..EVANS/HURLBUT.. 06/06/2009
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
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