DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 030455
SWODY1
SPC AC 030453

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1153 PM CDT TUE OCT 02 2012

VALID 031200Z - 041200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
A LARGE-SCALE UPPER-LEVEL TROUGH FROM THE MID-MS VALLEY TO THE WRN
GULF COAST WILL EJECT NEWD AND UNDERGO DE-AMPLIFICATION AS IT MOVES
INTO THE WRN EXTENT OF A STRONG RIDGE EXTENDING FROM THE WRN
ATLANTIC TO NEW ENGLAND. MEANWHILE...A COMPACT...VIGOROUS SHORTWAVE
TROUGH WILL DIG FROM THE NRN ROCKIES TO THE NRN PLAINS. A SHARP COLD
FRONT ATTENDANT TO THE LATTER TROUGH WILL SWEEP S/SEWD ACROSS THE
NRN/CNTRL PLAINS. A SURFACE LOW DEVELOPING OVER SWRN/SRN SD BY 12Z
TODAY WILL TRACK ENEWD INTO THE UPPER MS VALLEY...WITH THE
AFOREMENTIONED COLD FRONT EXPECTED TO EXTEND FROM ERN MN SSWWD
THROUGH ERN IA...NWRN MO TO NRN-SWRN OK TO WEST CENTRAL TX. IN THE
EAST...A COLD FRONT WILL DECAY E OF THE APPALACHIANS.

...MID-ATLANTIC REGION TO THE NORTHEAST...
AN ELONGATED WARM CONVEYOR/MOIST PLUME IS EXPECTED TO PERSIST FROM
THE ERN GULF BASIN ACROSS THE CAROLINAS INTO SRN NEW ENGLAND. VERY
WEAK LAPSE RATES WITHIN THIS CORRIDOR WILL CONTRIBUTE TO MEAGER
INSTABILITY THAT MAY PROVE ADEQUATE FOR DEEP CONVECTION ALONG THE
DECAYING FRONT. SOME UPDRAFTS MAY BE ROBUST ENOUGH TO PRODUCE
ISOLATED LIGHTNING. IN THE ABSENCE OF MEANINGFUL FORCING...GIVEN
RIDGING ALOFT...IT APPEARS ENVIRONMENTAL FACTORS WILL BE INADEQUATE
TO WARRANT SEVERE PROBABILITIES THIS PERIOD.

...ERN MT INTO ND AND PART OF NWRN SD...
STRONG UPWARD VERTICAL MOTION IMMEDIATELY DOWNSTREAM OF THE DIGGING
SHORTWAVE TROUGH AND INCREASING LOW LEVEL WAA ATTENDANT TO AN E/SELY
LLJ N OF THE SD LOW SHOULD PROVE SUFFICIENT TO SUPPORT ELEVATED
TSTMS ACROSS ERN MT TO ND. WHILE WEAK INSTABILITY WILL SUPPORT
CONVECTION/EMBEDDED TSTMS /SOME ONGOING AT 12Z TODAY/...SEVERE
WEATHER IS NOT EXPECTED GIVEN THE PRESENCE OF WEAK BULK SHEAR
LIMITING THE POTENTIAL FOR STORM ORGANIZATION.

...CENTRAL PLAINS TO MID MO VALLEY...
DESPITE STEEP LOW/MID-LEVEL LAPSE RATES SPREADING ACROSS THESE AREAS
AND DIABATIC HEATING...POOR MOISTURE RETURN AHEAD OF THE APPROACHING
COLD FRONT WILL LIKELY INHIBIT SURFACE-BASED TSTM DEVELOPMENT THIS
AFTERNOON. A GREATER THREAT EXISTS FOR POST-FRONTAL/ELEVATED TSTMS
FORMING WEDNESDAY NIGHT...GIVEN POTENTIAL SATURATION NEAR 700 MB
AND AN INCREASE IN WAA IN THE 850-700 MB LAYER. ELEVATED INSTABILITY
TO AROUND 500 J/KG COMBINED WITH STEEP MIDLEVEL LAPSE RATES AND
MODERATE CLOUD-BEARING SHEAR COULD YIELD SMALL HAIL WITH THE
STRONGER ACTIVITY.

...LOWER MS VALLEY AND MID SOUTH REGION...
ISOLATED TSTMS MAY DEVELOP WITHIN THE BASE OF EJECTING UPPER TROUGH
OVER PORTIONS OF THE LOWER MS VALLEY AND MID SOUTH. DAYTIME HEATING
WILL PROVE INSTRUMENTAL IN CONVECTIVE DEVELOPMENT BENEATH A POCKET
OF COLD MIDLEVEL TEMPERATURES...BUT WEAK LARGE SCALE FORCING SHOULD
TEND TO LIMIT THE OVERALL COVERAGE.

..PETERS/HURLBUT.. 10/03/2012

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