DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 161632
SWODY1
SPC AC 161630

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1030 AM CST SUN DEC 16 2012

VALID 161630Z - 171200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM CSTL TX ENE INTO THE CNTRL
GULF CST STATES...

...SYNOPSIS...
MODERATE TO FAST WSW FLOW WILL CONTINUE FROM THE S CNTRL STATES TO
THE MID ATLANTIC CST...ON NRN FRINGE OF PERSISTENT GULF OF MEXICO
RIDGE. SEVERAL DISTURBANCES IN THIS FLOW WILL MODULATE TSTM/SVR
POTENTIAL THROUGH THE PERIOD.

AN IMPULSE/JET STREAK NOW IN S CNTRL TX SHOULD CONTINUE ENE TO THE
ARKLAMS BY EVE...AND INTO THE SRN APPALACHIANS EARLY
MON...DEAMPLIFYING IN THE PROCESS. FARTHER N...STRONGER SHORTWAVE
TROUGH NOW OVER SW KS ALSO SHOULD DEAMPLIFY AS IT SHEARS ENE INTO
CONFLUENT FLOW OVER THE LWR OH VLY/MIDWEST. FINALLY...UPSTREAM
TROUGH NOW IN AZ MAY SOMEWHAT STRENGTHEN AS IT CONTINUES ESE INTO
THE SRN PLNS TNGT/EARLY MON. THIS WILL SERVE TO STRENGTHEN MID/UPR
LVL FLOW ACROSS THE S CNTRL AND SERN STATES LATER IN THE PERIOD.

AT LWR LVLS...MAIN FEATURE OF NOTE WILL BE SHALLOW RAIN-REINFORCED
QSTNRY FRONT ATTM EXTENDING FROM S CNTRL TX ENE INTO MS/AL. THIS
BOUNDARY LIKELY WILL REMAIN NEARLY STNRY THROUGH THE PERIOD AND WILL
BE THE FOCUS OF THE STRONGEST CONVECTION/STORMS. FARTHER N AND
NW...SHALLOW COLD FRONT NOW EXTENDING FROM LK MI SW INTO THE CNTRL
HI PLNS MAY BECOME BETTER DEFINED WITH TIME AS FRONTOGENESIS OCCURS
IN ITS VICINITY IN RESPONSE TO UPR SYSTEM AMPLIFYING ESEWD FROM AZ.

...CSTL TX ENE INTO THE CNTRL GULF CST STATES TODAY/TNGT...
AN EXTENSIVE BAND OF SHOWERS/TSTMS LIKELY WILL PERSIST THROUGH THE
PERIOD ALONG AFOREMENTIONED QSTNRY FRONT FROM CSTL TX NE INTO
LA...MS...AND AL. THE FOCUS FOR STRONGEST DEVELOPMENT SHOULD SHIFT
SLOWLY EWD WITH TIME AS /1/ TX UPR IMPULSE CONTINUES ENEWD AND /2/
ASSOCIATED CONFLUENT LLJ EDGES EWD INTO LA/MS FROM CURRENT POSITION
IN SE TX.

COMBINATION OF MODERATE TO STRONG CLOUD-LAYER SHEAR...MOISTENING
LOW-LVL ENVIRONMENT /PWS INCREASING TO 1.50-1.75 INCHES/...A WEAK
ELONGATING COLD POOL...AND PERSISTENT UPR DIVERGENCE WILL YIELD A
SETUP FAVORABLE FOR A LONG-LIVED WSW-ENE ORIENTED QLCS. EMBEDDED
SUSTAINED STORMS/OCCASIONAL SUPERCELLS MOVING PARALLEL TO THE
SLOWLY-PROGRESSIVE BOUNDARY WILL HAVE THE POTENTIAL TO PRODUCE
LOCALLY DMGG WIND AND POSSIBLY A TORNADO OR TWO...ESPECIALLY LATER
TODAY/TNGT AS LOW LVL AIR MASS MOISTENS AND 700 MB FLOW STRENGTHENS
TO AROUND 50 KTS OVER THE CNTRL GULF CST STATES. A LIMITED RISK ALSO
WILL EXIST FOR A FEW STORMS TO FORM AHEAD OF THE BOUNDARY FROM CSTL
TX THIS AFTN...INTO PARTS OF LA/MS AND AL LATER TODAY/TNGT.

...LWR OH VLY...
APPROACH OF AMPLIFYING AZ UPR IMPULSE...AND MOISTENING AHEAD OF
IT...MAY YIELD A SEPARATE AREA OF SHOWERS/STORMS LATE TNGT/EARLY MON
OVER PARTS OF THE LWR OH VLY. COOL MID LVL TEMPS AND PRESENCE OF
AMPLE CLOUD-LAYER SHEAR FOR SUSTAINED STORMS MAY SUPPORT A FEW CELLS
CAPABLE OF HAIL...ALTHOUGH OVERALL SVR POTENTIAL LOOKS QUITE LOW.

..CORFIDI/COHEN.. 12/16/2012

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