SWODY2
SPC AC 281716
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1216 PM CDT WED SEP 28 2011
VALID 291200Z - 301200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
STACKED CYCLONE OVER THE MIDWEST WILL FINALLY EJECT ENE ON THU AS
AMPLIFYING UPR SYSTEM...NOW OVER SRN CANADA...DIGS INTO THE GRTLKS
REGION. AT THE SFC...BAROCLINIC ZONE ALONG THE APLCN MOUNTAINS WILL
BECOME REINFORCED AS THE MIDWEST DISTURBANCE ACCELERATES TO THE
ENE...MOVING TO THE ERN SEABOARD BY THU EVE. TAIL-END OF THE SAME
FRONT WILL REMAIN ALONG THE GULF COAST AND CNTRL TX.
MEANWHILE...VIGOROUS LOW/MID-LVL FRONTOGENESIS WILL OCCUR FROM LK MI
SWD INTO THE CNTRL PLAINS THU AFTN. THIS FRONT WILL RAPIDLY
TRANSLATE ACROSS THE MIDWEST...OH VLY AND SRN PLAINS THU NIGHT.
...MID-ATLANTIC REGION NWD INTO NY AND WRN NEW ENGLAND...
EJECTION OF THE MIDWEST UPR LOW WILL BE ACCOMPANIED BY STRONG
ASCENT/120+ METER H5 HEIGHT FALLS/ ACROSS THE REGION FROM LATE THU
MORNING INTO THE AFTN. RESULTANT DEEPENING/STRENGTHENING FRONTAL
CIRCULATION WILL SUPPORT BANDS OF CONVECTION/EMBEDDED TSTMS.
CLOUDS/PCPN WILL LIMIT BOUNDARY LAYER DESTABILIZATION...
PARTICULARLY N OF PA. BUT...LOCAL DIABATIC HEATING WILL RESULT IN
POCKETS OF STRONGER INSTABILITY. AT THIS POINT...THERE REMAINS
ENOUGH UNCERTAINTY ON AREAL EXTENT/MAGNITUDE OF BUOYANCY TO MAINTAIN
LOW PROBABILITIES OF SVR WIND/HAIL. OTHERWISE... DEEP-LAYER SHEAR
WILL BE MORE THAN SUFFICIENT FOR ROBUST UPDRAFTS/BRIEF SUPERCELLS.
PARTS OF THE REGION MAY NEED A SLGT RISK UPGRADE IN LATER OTLKS.
...MIDWEST...
ALTHOUGH MOISTURE PROFILES WILL NOT BE PARTICULARLY IMPRESSIVE... AT
LEAST MID-50S SFC DEW POINTS COMBINED WITH HEATING ALONG/AHEAD OF
THE INTENSIFYING FRONT WILL CONTRIBUTE TO A FEW HUNDRED J/KG MLCAPE
BY THU AFTN. EXPECT A FORCED-LINE OF CONVECTION/EMBEDDED TSTMS TO
FORM ACROSS LK MI AND ERN IL EARLY THU AFTN AND PROGRESS RAPIDLY ESE
INTO THE OH VLY BY EVENING. INCREASINGLY WLY LOW/MID-LVL FLOW OF
45-50 KTS WILL RESULT IN BOWING LINE SEGMENTS WITH RISKS OF
SPORADIC/ISOLD DMGG WIND GUSTS AND HAIL. ACTIVITY SHOULD DIMINISH
AFTER SUNSET.
...S TX...
STRONG BOUNDARY LAYER HEATING WILL ONCE AGAIN BE NOTED ACROSS THE
SRN PLAINS...ESPECIALLY MUCH OF CNTRL/SOUTH TX. IN THE MEAN...NWLY
FLOW WILL GRADUALLY DEEPEN ACROSS THIS PORTION OF THE COUNTRY AND A
PRE-FRONTAL WIND SHIFT WILL LIKELY SETTLE TO A POSITION NEAR THE
BALCONES ESCARPMENT BY PEAK HEATING. ALTHOUGH VERTICAL SHEAR WILL
REMAIN WEAK...A FEW HIGH BASED STORMS COULD PRODUCE DMGG WINDS AS
TEMP/DEW POINT SPREADS APPROACH 40-50 DEG WITH COINCIDENT WITH AFTN
READINGS IN THE UPPER 90S-100F.
..RACY.. 09/28/2011
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