SWODY1
SPC AC 060049
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0749 PM CDT SUN AUG 05 2007
VALID 060100Z - 061200Z
..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE NRN ROCKIES
TO THE NRN PLAINS...
..THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF THE MIDWEST
FROM IL ACROSS OH...
..UPPER MIDWEST...
BROAD UNSTABLE WARM SECTOR EXTENDS FROM MO/IA EWD ACROSS IL/IND/OH
THIS EVENING AND IS DELINEATED ON THE NRN PERIPHERY BY A WEAK
QUASI-STATIONARY FRONTAL ZONE FROM SWRN IA TO SRN LAKE MI TO NERN
OH. CONVECTION ACROSS THE REGION HAS SO FAR BEEN SPARSE AND HAS
LIKELY BEEN LIMITED BY BOTH WEAK MID LEVEL LAPSE RATES AND LACK OF
STRONGER FORCING ALONG THE BOUNDARY AND OVER THE WARM SECTOR. LATEST
NAM/RUC AND CALIBRATED SREF THUNDER PROBABILITIES MAINTAIN THE
PROSPECTS FOR AT LEAST SCATTERED TSTMS FROM IL EWD TO OH OVER THE
NEXT SEVERAL HOURS. THIS GUIDANCE APPEARS TO BE SUPPORTED BY RECENT
STORM DEVELOPMENT IN NRN IL. THIS ACTIVITY...ALONG WITH A FEW CELLS
ACROSS OH...HAS SHOWN AN INCREASE OVER THE PAST 1-2 HOURS.
EFFECTIVE SHEAR ACROSS THE REGION IS SUFFICIENT FOR UPDRAFT
ORGANIZATION/PERSISTENCE AND EXPECT ONE OR TWO STORM CLUSTERS TO
POSSIBLY GROW UPSCALE AND SPREAD GENERALLY EWD TONIGHT. WHILE HAIL
POTENTIAL WITH THIS ACTIVITY MAY BE LIMITED BY WARM TEMPERATURES
ALOFT...LOW LEVEL SHEAR AND POSSIBILITY OF UPSCALE/SMALL MCS
DEVELOPMENT INDICATES TORNADO/DAMAGING WIND POTENTIAL CANNOT BE
RULED OUT...ESPECIALLY OVER THE NEXT FEW HOURS.
..CNTRL/NRN PLAINS...
A NUMBER OF INTENSE SUPERCELLS INITIATED DURING THE LATE
AFTERNOON/EARLY EVENING ACROSS NRN NEB NWD INTO WCNTRL SD. THIS
ACTIVITY APPEARS TO HAVE OCCURRED NEAR LEE/THERMAL TROUGH AND
RESIDUAL FRONTAL BOUNDARY INTERSECTION ACROSS THE AREA AND MAY HAVE
BEEN FURTHER SUPPORTED BY VERY SUBTLE SHORT WAVE TROUGH PASSAGE
ALOFT. ONGOING ACTIVITY APPEARS TO BE IDEALLY LOCATED WITHIN NARROW
INSTABILITY AXIS WHERE STRONG /40-60KT/ EFFECTIVE BULK SHEAR ALSO
EXISTS. MODEL GUIDANCE INDICATES THAT CONVECTION IN THIS REGION MAY
NOT PERSIST LONG...PERHAPS DUE TO STRONG DIURNAL COMPONENT TO RECENT
DEVELOPMENT AND UPCOMING ONSET OF GRADUAL DIURNAL COOLING. GIVEN
CURRENT INTENSITY AND LOCATION OF ONGOING STORMS...A HIGHER
PROBABILITY HAIL/WIND AREA WILL BE MAINTAINED IN THIS OUTLOOK. IN
ADDITION...COLD FRONT ACROSS NRN SD COULD PROVIDE A BETTER FOCUS TO
SUSTAIN STORMS IN THIS AREA FOR A COUPLE MORE HOURS.
..ROCKIES...
WATER VAPOR IMAGERY DEPICTS POTENT SHORT WAVE VORTEX EJECTING OUT OF
THE LARGER SCALE TROUGH OVER THE PACIFIC NORTHWEST. LARGE SCALE
DYNAMIC FORCING/DPVA ASSOCIATED WITH THIS IMPULSE IS APPARENTLY
OVERCOMING LACK OF GREATER DESTABILIZATION AND AIDING SCATTERED
HIGH-BASED TSTMS ACROSS THE NRN GREAT BASIN AND INTO THE ROCKIES
THIS AFTERNOON. LIFT ACROSS THE MOUNTAINS...AND ALONG/ACROSS THE
DEEP-LAYER SYNOPTIC FRONT BACKED INTO THE SRN MT/NRN WY WILL
CONTINUE TO SUPPORT CONVECTION SPREADING ENEWD ATOP WARM/DRY
BOUNDARY LAYER AIR MASS. FORCING WITH THIS IMPULSE IS FORECAST TO
INDUCE LEE-SIDE CYCLOGENESIS ALONG THE FRONT OVER NERN WY/SERN MT
LATER TONIGHT. THIS DEVELOPMENT MAY MAINTAIN/SUSTAIN THE RISK FOR
TSTMS...PERHAPS IN THE FORM OF AN MCS...ACROSS THE NRN HIGH PLAINS
/ERN MT TO WRN ND/ INTO EARLY MONDAY MORNING.
..MID ATLANTIC...
WELL-DEFINED MCV AND ASSOCIATED LARGE CLUSTER OF POORLY ORGANIZED
CONVECTION WAS BRINGING LOCALLY HEAVY RAIN TO PARTS OF THE MID
ATLANTIC REGION TONIGHT. AIR MASS ACROSS MOST OF THE REGION HAS BEEN
THOROUGHLY OVERTURNED BY ONGOING STORMS WITH THE POSSIBLE EXCEPTION
OF SMALL AREAS OF SRN/SERN VA...AND PERHAPS ERN DELMARVA PENINSULA.
A STRONG TO ISOLATED SEVERE WIND GUST MAY OCCUR IN THE NEXT HOUR OR
SO PRIOR TO REMAINING INSTABILITY BEING DIMINISHED.
.CARBIN.. 08/06/2007
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