SWODY1
SPC AC 141627
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1127 AM CDT MON MAY 14 2007
VALID 141630Z - 151200Z
..THERE IS A SLGT RISK OF SVR TSTMS FROM THE NRN/WRN GREAT LAKES
ACROSS THE CENTRAL PLAINS...
..THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF CENTRAL/SRN FL...
..THERE IS A SLGT RISK OF SVR TSTMS ACROSS SRN LA INTO ERN TX...
..NRN MS RIVER VALLEY ACROSS THE NRN/WRN GREAT LAKES...
MESSY SEVERE WEATHER SCENARIO EXPECTED TO EVOLVE ACROSS THIS REGION
AHEAD OF POSITIVELY-TILTED SHORTWAVE TROUGH SHIFTING EWD OVER THE
NRN PLAINS. SURFACE COLD FRONT WAS WELL DEFINED THIS MORNING
TRAILING SWWD FROM LOW OVER NRN MN INTO SERN CO...WITH WARM FRONT
EXTENDING ESEWD ACROSS FAR NRN WI AND INTO THE CENTRAL GREAT LAKES.
VISIBLE SATELLITE IMAGERY INDICATES STRONG HEATING IS EXPECTED OVER
MUCH OF THE REGION WHICH WILL HELP PUSH WARM FRONT NWD ACROSS MUCH
OF THE MI U.P. THIS AFTERNOON. MEANWHILE...SURFACE LOW IS EXPECTED
TO TRACK EWD INTO THE WRN U.P. OF MI BY LATER TODAY WITH SURFACE
COLD FRONT MOVING ACROSS THE NRN MS RIVER VALLEY AND INTO THE
CENTRAL PLAINS. WARM SECTOR WILL BECOME UNSEASONABLY WARM WITH
NEAR-RECORD HIGHS EXPECTED INTO MUCH OF MN/WI/WRN U.P. OF MI. THIS
WILL HELP MIX THROUGH VERY STRONG CAPPING BENEATH PRONOUNCED EML
EVIDENT ON MORNING SOUNDINGS. IN ADDITION...MOISTURE ADVECTION
SHOULD SOMEWHAT OFFSET DRYING DUE TO DEEP MIXING OF THE BOUNDARY
LAYER AND MODELS CONTINUE TO MAINTAIN NEAR 60F SURFACE DEW POINTS
AHEAD OF APPROACHING COLD FRONT. THUS...LARGE AREA OF MODERATE TO
STRONG INSTABILITY IS EXPECTED WITH MLCAPE EXCEEDING 2000 J/KG.
STRONG ELEVATED INSTABILITY WITH MUCAPE AROUND 3000 J/KG WILL
CONTINUE TO FEED STORMS NEAR LAKE SUPERIOR THROUGH THE
MORNING...WHICH MAY SUPPORT ISOLATED LARGE HAIL INTO THE EARLY TO
MID AFTERNOON. SLIGHTLY ELEVATED STORMS MAY ALSO BEGIN DEVELOPING
ACROSS SRN MN AHEAD OF COLD FRONT BY THE MID AFTERNOON. ACTIVITY
SHOULD BECOME SURFACE-BASED BY 21Z WITH INCREASED RISK OF DAMAGING
WINDS AND POSSIBLY A TORNADO OR TWO. TORNADO POTENTIAL WILL LIKELY
REMAIN HIGHER NEAR THE LOW CENTER OVER NRN WI AND WRN U.P. OF MI
WHERE SHEAR VALUES WILL BE MUCH MORE FAVORABLE FOR SUPERCELLS. WIND
DAMAGE AND LARGE HAIL THREAT WILL BECOME MORE WIDESPREAD THROUGH THE
EVENING ACROSS WI AND NRN/WRN IA AS ACTIVITY EVOLVES INTO
LINES/CLUSTERS WITH BOWING SEGMENTS.
..CENTRAL PLAINS...
STORMS WILL LIKELY BECOME SCATTERED TO NUMEROUS LATER THIS AFTERNOON
AND EVENING ALONG AND JUST BEHIND SLOW MOVING SURFACE COLD FRONT
FROM ERN NEB INTO THE ERN CO/NWRN KS. THIS ACTIVITY WILL LIKELY
EVOLVE INTO A BROKEN SQUALL LINE AND SHIFT SSEWD THROUGH THE NIGHT.
THOUGH FRONT WILL FOCUS AND SUSTAIN SOME LINEAR ORGANIZATION...DEEP
LAYER SHEAR VALUES WILL REMAIN QUITE MARGINAL FOR SUSTAINED
STORM-SCALE ORGANIZATION /ESPECIALLY AS STORMS PROGRESS FARTHER
SSEWD AFTER DARK/. GIVEN EXPECTED MODERATE INSTABILITY AND
SUSTAINED LOW LEVEL CONVERGENCE...LARGE HAIL AND DAMAGING WINDS
SHOULD ACCOMPANY STRONGER STORMS THROUGH MUCH OF THE EVENING.
..CENTRAL/SRN FL...
LAPSE RATES REMAIN FAIRLY STEEP THIS MORNING AT TBW AND MFL WITH
CONSIDERABLY MORE MOISTURE AND SLIGHTLY LESS LAPSE RATES THAN WERE
THE CASE YESTERDAY. DEEP ELY FLOW SHOULD MAXIMIZE CONVERGENCE INTO
W-CENTRAL/SWRN FL BY LATER TODAY...WHERE STORMS SHOULD BECOME QUITE
NUMEROUS. THOUGH STORMS WILL LIKELY BE PULSE-TYPE OR AT BEST
MULTICELLULAR...COLD AIR ALOFT AND MODERATE TO STRONG INSTABILITY
SHOULD SUPPORT LARGE HAIL AND ISOLATED DAMAGING WINDS DURING THE
AFTERNOON/EVENING.
..SERN TX ACROSS SRN LA...
12Z SOUNDING AT LCH INDICATES MID LEVEL LAPSE RATES REMAIN QUITE
STEEP /H5 TEMPS AROUND -11C/ ATOP A VERY MOIST BOUNDARY LAYER ACROSS
SRN LA INTO PARTS OF ERN TX. IN ADDITION...WEAK SURFACE TROUGH WILL
REMAIN IN PLACE ACROSS THIS REGION WHICH WILL FOCUS SCATTERED TO
NUMEROUS THUNDERSTORMS ONCE AGAIN THIS AFTERNOON. GIVEN AMOUNT OF
INSTABILITY /MLCAPE FROM 1500-2000 J/KG/ AND COLD MID LEVEL
AIR...LARGE HAIL WILL ONCE AGAIN BE LIKELY WITH THE STRONGER CORES.
THOUGH ACTIVITY WILL BE PULSE IN NATURE GIVEN LACK OF
SHEAR...SURFACE TROUGH MAY FOCUS/CONCENTRATE ACTIVITY SUFFICIENT FOR
HIGHER PROBABILITIES OF LARGE HAIL AND CATEGORICAL SLGT RISK FOR
LATER TODAY AND THIS EVENING.
.EVANS/GRAMS.. 05/14/2007
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