SWODY1
SPC AC 041949
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0249 PM CDT SAT JUN 04 2011
VALID 042000Z - 051200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE MID-MO
VALLEY...MID-MS VALLEY AND OH VALLEY...
THE ONLY SIGNIFICANT CHANGE FOR THE 20Z OUTLOOK IS TO THE NARROW THE
SEVERE PROBABILITIES ACROSS ERN NM AND FAR WEST TX WHERE INSTABILITY
IS MAXIMIZED AND THE CONVECTIVE POTENTIAL IS GREATEST.
OTHERWISE...ONLY MINOR ADJUSTMENTS TO THE LINES HAVE BEEN MADE FOR
THIS OUTLOOK.
..BROYLES.. 06/04/2011
.PREV DISCUSSION... /ISSUED 1122 AM CDT SAT JUN 04 2011/
...SYNOPSIS...
EXPANSIVE UPPER RIDGE IS NOW CONTROLLING CIRCULATION OVER MUCH OF
CONUS AS AN ANOMALOUSLY DEEP COLD LOW STALLS OFF CA COAST AND
PRIMARY WESTERLIES REMAIN ACROSS SRN CANADA.
COLD FRONT THIS MORNING STRETCHES WSWWD ACROSS CENTRAL LWR MI TO
IL/WI BORDER AND THEN NWRN MO TO SE CO. ERN PORTION OF FRONT WILL
CONT SLOW SEWD MOVEMENT TOWARD LOWER LAKES AND INTO NRN OH VALLEY
WHILE TRAILING PORTION STALLS. PORTION OF FRONT CENTRAL HI PLAINS
WILL LIKELY DRIFT A LITTLE N THIS AFTERNOON AS UPSLOPE FLOW DEVELOPS
ACROSS ERN CO.
A RESERVOIR OF MOIST AND VERY UNSTABLE AIR RESIDES JUST AHEAD OF
COLD FRONT FROM MID MS VALLEY EWD TO SRN LM/IND...GRADUALLY
SPREADING FURTHER E THIS AFTERNOON.
...MID MS AND OH VLYS TO LWR GRT LKS THIS AFTERNOON AND EARLY
TNGT...
THE CURRENT MCS RIDING SEWD ATOP THE RIDGE IS MOVING ACROSS ERN LE
INTO NWRN PA. EXPECT THE OBSERVED INSTABILITY AHEAD OF THIS SYSTEM
TO BE INSUFFICIENT TO MAINTAIN A SEVERE THREAT BEYOND ISOLATED
DAMAGING WIND GUSTS IN THE NEAR TERM INTO NWRN PA.
MODERATE TO STRONG INSTABILITY...WITH SBCAPE AOA 3500 J/KG...IS
ALREADY AVAILABLE S OF FRONT FROM NRN IL INTO NRN IND. WITH THE CAP
NEARLY GONE...POTENTIAL FOR STRONG/SEVERE THUNDERSTORMS WILL
INCREASE BY EARLY/MID AFTERNOON ALONG/AHEAD OF COLD FRONT. DEEP
LAYER SHEAR AROUND 30KT WILL BE ADEQUATE FOR STORM ORGANIZATION WITH
STEEP LAPSE RATES AND CAPE SUPPORTIVE OF BOTH LARGE HAIL AND
DAMAGING WINDS. LARGELY UNIDIRECTIONAL DEEP WLY FLOW SHOULD
SUPPORT DEVELOPMENT OF ONE OR TWO MCSS THAT WILL MOVE MAINLY ESE
ALONG/AHEAD OF FRONT. THIS UPSCALE GROWTH COULD LEAD TO A GREATER
WIND DAMAGE THREAT BY LATER THIS AFTERNOON/EVENING.
ADDITIONAL CLUSTER OF STORMS MAY DEVELOP NEAR THE FRONT THIS
AFTERNOON AND PERSIST WELL INTO THE NIGHT IN AREA OF
STRONGER WAA OVER OH/WV/WRN PA. FURTHER W ACROSS SRN IA INTO NRN MO
POTENTIAL OF MORE SCATTERED THUNDERSTORMS INCLUDING A SEVERE THREAT
EXISTS THIS AFTERNOON...BUT SHOULD BE LESS COVERAGE THAN FURTHER E
UNDER A WEAKER SHEAR REGIME.
...CNTRL/SRN HI PLNS THIS AFTN/EVE...
UPSLOPE TO N OF STALLED FRONTAL ZONE SHOULD LEAD TO SCATTERED
THUNDERSTORMS DEVELOPING OFF THE HIGHER TERRAIN ERN CO AND DRIFTING
EWD ACROSS THE PLAINS. THE FAVORABLE DIRECTIONAL SHEAR AND MLCAPES
AOA 1500 J/K WILL BE SUPPORTIVE OF AT LEAST ISOLATED SEVERE
THUNDERSTORMS INCLUDING SUPERCELLS. PRIMARILY HAIL WILL BE THE
INITIAL THREAT FROM THESE STORMS...BUT CAN NOT RULE OUT
SUPERCELLS/ISOLATED TORNADO'S BY THIS EVENING AS STORMS DEVELOP EWD
ACROSS THE PLAINS OF CO.
...GULF CST REGION THIS AFTN/EARLY EVE...
MODERATE TO STRONG INSTABILITY IS AGAIN DEVELOPING WITH SFC HEATING
TODAY ALONG THE GULF CST FROM SE TX/LA EWD INTO FL AS TEMPS WARM
WELL INTO THE 90S. SCTD TSTMS SHOULD FORM ACROSS THE REGION...WITH
STEEP LOW LVL LAPSE RATES AND WEAK SHEAR POSSIBLY SUPPORTING A FEW
WET MICRO BURSTS AND/OR SVR HAIL EVENTS...MAINLY BETWEEN 20-02Z.
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