DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 080552
SWODY1
SPC AC 080550

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1150 PM CST FRI DEC 07 2012

VALID 081200Z - 091200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...

BROAD CYCLONIC FLOW REGIME WILL PERSIST ACROSS THE NATION SATURDAY
WITH A GENERAL AMPLIFICATION OF A TROUGH OVER THE NRN AND CNTRL
ROCKIES IN ASSOCIATION WITH A STRONG UPPER JET MAX NOW DROPPING SEWD
INTO THE PACIFIC NW. PROGRESSIVE SHORTWAVE TROUGH OVER THE UPPER MS
VALLEY WILL MOVE THROUGH THE GREAT LAKES...REACHING THE NERN STATES
SATURDAY NIGHT. COLD FRONT ACCOMPANYING THIS FEATURE WILL CONTINUE
THROUGH THE NERN STATES...BUT TRAILING SECTIONS WILL STALL FROM NRN
TX THROUGH AR...AND MAY BEGIN A SLIGHT NWD RETREAT SATURDAY NIGHT.
MEANWHILE A STRONG COLD FRONT WILL ACCELERATE SEWD THROUGH THE
PLAINS...LIKELY EXTENDING FROM NWRN TX THROUGH KS INTO THE UPPER MS
VALLEY BY THE END OF THIS PERIOD.

...ERN OK AND NERN TX THROUGH LOWER MS AND TN VALLEY REGIONS...

MODIFIED CP AIR WITH DEWPOINTS IN THE LOW TO MID 60S WILL CONTINUE
TO ADVECT NEWD THROUGH THE WARM SECTOR ACROSS ERN TX INTO THE LOWER
MS VALLEY REGION. WHERE LOW CLOUDS MIX OUT...DIABATIC WARMING WILL
LIKELY BOOST MLCAPE TO AROUND 1000 J/KG ACROSS ERN TX WITH WEAKER
INSTABILITY FARTHER NORTH INTO THE LOWER MS VALLEY. A FEW SHOWERS
AND A COUPLE ISOLATED THUNDERSTORMS CANNOT BE RULED OUT SATURDAY
AFTERNOON...BUT CONVECTIVE POTENTIAL DURING THE DAY WILL PROBABLY
REMAIN LIMITED OWING TO WEAK FORCING AND LIKELIHOOD OF AT LEAST A
MODEST CAP.

THUNDERSTORM POTENTIAL SHOULD IMPROVE SATURDAY NIGHT FROM ERN OK AND
ESPECIALLY THE LOWER MS VALLEY NORTH OF STALLED BOUNDARY WITHIN ZONE
OF DESTABILIZATION AND ISENTROPIC ASCENT ASSOCIATED WITH
STRENGTHENING LLJ. THIS ACTIVITY WILL LIKELY BE ELEVATED ABOVE THE
STABLE SFC LAYER. THREAT FOR MARGINALLY SEVERE HAIL CANNOT BE RULED
OUT GIVEN EFFECTIVE CLOUD LAYER SHEAR IN EXCESS OF 40
KT...ESPECIALLY FROM ERN OK INTO WRN AR WHERE INSTABILITY MAY BE
SLIGHTLY GREATER. MODEST MID LEVEL LAPSE RATES SHOULD SERVE AS AN
OVERALL LIMITING FACTOR FOR A MORE ROBUST HAIL THREAT.

..DIAL/MOSIER.. 12/08/2012

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