SWODY1
SPC AC 041251
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0751 AM CDT FRI JUN 04 2010
VALID 041300Z - 051200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE LWR MO/MID MS VLYS TO
THE LWR GRT LKS...
...THERE IS A SLGT RISK OF SVR TSTMS OVER THE CNTRL GULF CST/LWR MS
VLY...
...SYNOPSIS...
ZONAL FLOW WILL CONTINUE ACROSS THE NRN HALF OF THE NATION THIS
PERIOD...AS HEIGHTS SLOWLY RISE OVER THE SWRN STATES AND SE TX LOW
WEAKENS UPON MOVING E TO THE LA/MS BORDER. WITHIN THE WLYS...
SHORTWAVE TROUGH NOW OVER SRN SK WILL SHEAR ESE ACROSS THE UPR GRT
LKS...WHILE ADDITIONAL LWR AMPLITUDE FEATURES MOVE E OR ESE FROM THE
PACIFIC NW/NRN RCKYS TO THE MID MS VLY/GRT LKS.
FEATURES WILL REMAIN WEAK AT THE SFC. IN THE MEAN...HOWEVER...A
WAVY FRONTAL ZONE WILL PERSIST FROM NEB/IA INTO NY/NEW ENGLAND.
...MIDWEST/CNTRL GRT LKS THIS AFTN/EVE...
CONVECTIVELY-ENHANCED MID-LVL SHORTWAVE TROUGH NOW OVER WI/IA WILL
MOVE E ACROSS MI/IND LATER TODAY. UNCERTAINTY PERSISTS REGARDING
DEGREE OF LOW-LVL DESTABILIZATION AHEAD OF THE TROUGH GIVEN
DOWNSTREAM CLOUDS...SOMEWHAT LIMITED MOISTURE...AND RELATIVELY EARLY
TIMING OF THE WAVE. BEST ESTIMATE ATTM IS THAT THE GREATEST
DESTABILIZATION /WITH SBCAPE AOA 1500 J PER KG/ WILL OCCUR FROM E
CNTRL IL E INTO IND AND MOST OF OH.
TSTMS SHOULD FORM IN AREA OF SFC HEATING AHEAD OF CLOUD SHIELD FROM
CNTRL IL INTO IND/OH THIS AFTN. STORMS ALSO MAY FORM A BIT FARTHER
N IN ZONE OF CONFLUENT 850 MB FLOW OVER SRN LWR MI.
A FEW SUPERCELLS COULD OCCUR...ESPECIALLY OVER SRN MI/NRN IND AND
NRN OH. THESE COULD YIELD DMGG WIND AND A TORNADO. BUT
INCREASINGLY UNIDIRECTIONAL FLOW WITH TIME SUGGESTS THAT ACTIVITY
WILL TRANSITION TO BROKEN LINE SEGMENTS...WITH EMBEDDED SMALL BOWS
YIELDING DMGG WIND. THE STORMS MAY SPREAD AS FAR E AS THE LWR GRT
LKS BY EVE...WITH GRADUAL WEAKENING EXPECTED THEREAFTER.
...MID MS/MID MO VLYS THIS AFTN THROUGH TONIGHT...
IN WAKE OF WI/IA UPR IMPULSE...FLOW WILL REMAIN ZONAL/SLIGHTLY
CYCLONIC OVER THE MID MS/LWR MO VLY REGION THROUGH TONIGHT. STRONG
HEATING AND SUFFICIENT BOUNDARY LAYER MOISTURE SHOULD SUPPORT ISOLD
TSTM DEVELOPMENT ALONG WEAK FRONT FROM NW IL THROUGH SRN IA/NRN MO
INTO ERN NEB. COMBINATION OF STEEP MID-LVL LAPSE RATES AND 40 KT
WNWLY DEEP LAYER SHEAR COULD YIELD A COUPLE SUPERCELLS WITH LARGE
HAIL AND DMGG WINDS BY LATE IN THE DAY.
AN UPSTREAM DISTURBANCE NOW OVER ORE SHOULD APPROACH THE LWR MO VLY
TONIGHT. COUPLED WITH DIURNAL STRENGTHENING OF SWLY LLJ...SETUP MAY
SUPPORT ADDITIONAL STRONG TO SVR STORMS FROM NRN/ERN NEB ESE INTO
IA. THIS ACTIVITY MAY GROW INTO AN MCS OR TWO...WHILE OTHER
ACTIVITY PERSISTS ESE INTO IL/IND. SUFFICIENT CLOUD LAYER SHEAR AND
CAPE WILL EXIST FOR A CONTINUED THREAT FOR SVR HAIL...AND POSSIBLY
DMGG WIND...THROUGH EARLY SAT.
...CNTRL GULF CST THROUGH LATE THIS AFTN...
A BAND OF 30-40 KT UNIDIRECTIONAL LOW- TO MID-LVL SW FLOW WILL CROSS
ERN LA/SRN MS TODAY...IN ERN SEMICIRCLE OF SLOWLY MOVING UPR LOW NOW
OVER SE TX. DAYTIME HEATING OF WEAKLY CAPPED ENVIRONMENT SHOULD
SUPPORT INTENSIFICATION OF TSTMS NOW PRESENT IN AN ARC ALONG COLD
FRONT-LIKE FEATURE FROM NEAR KPOE THROUGH KLFT INTO THE GULF.
PERSISTENT MULTICELLS/SMALL BOWS WITHIN THIS ACTIVITY COULD YIELD
DMGG WIND GIVEN 35-40 KT MEAN FLOW. MORE ISOLD STORMS MAY
FORM/INTENSIFY AHEAD OF THIS BAND ALONG WEAK WARM FRONT/WIND SHIFT
EXTENDING E INTO SRN MS. THE LATTER STORMS COULD PRODUCE A TORNADO
OR TWO GIVEN LOW LCLS AND MODEST BUT BACKED LOW LVL FLOW.
...S ATLANTIC CST THIS AFTN...
ANOTHER ROUND OF DIURNALLY-ENHANCED TSTMS WILL DEVELOP ALONG
RESIDUAL OUTFLOW AND SEA BREEZE BOUNDARIES TODAY...ESPECIALLY OVER
CNTRL/ERN FL NWD INTO CSTL SC/GA. FORECAST SOUNDINGS SHOW DEEP AND
SUBSTANTIAL CAPE WITH WEAK SHEAR. SETUP MAY YIELD A FEW STORMS WITH
LOCALLY DMGG WIND/SVR HAIL.
...TN VLY/CNTRL APPALACHIANS THIS AFTN...
OLD STNRY FRONT EXTENDING SW-NE FROM THE LWR TN VLY TO THE CNTRL
APPALACHIANS MAY SERVE AS ANOTHER FOCUS FOR DIURNALLY-ENHANCED
TSTMS. REGION WILL BE REMOVED FROM THE FASTER WLYS...SUGGESTING
THAT PULSE MULTICELLS WILL BE THE DOMINANT CONVECTIVE MODE. A FEW
LOCALLY DMGG WIND AND/OR MARGINALLY SVR HAIL EVENTS MAY OCCUR.
..CORFIDI/STOPPKOTTE.. 06/04/2010
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