DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 160701
SWODY2
SPC AC 160659

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1259 AM CST SAT NOV 16 2013

VALID 171200Z - 181200Z

...THERE IS A MDT RISK OF SVR TSTMS FROM EXTREME ERN IL INTO
IND...OH...SRN MI AND NRN KY...

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE GREAT LAKES THROUGH
THE OH AND TN VALLEYS AND A PORTION OF THE NERN AND SERN STATES...

...SYNOPSIS...

A STRONG UPPER JET NOW EVIDENT IN SATELLITE IMAGERY DROPPING SEWD
INTO THE PACIFIC NW WILL CONTINUE THROUGH BASE OF SYNOPTIC SCALE
TROUGH. ATTENDANT SHORTWAVE TROUGH WILL EJECT NEGATIVELY TILTED
THROUGH THE MID MS...OH VALLEYS AND GREAT LAKES SUNDAY...REACHING
WRN PORTIONS OF THE NERN U.S. TOWARD THE END OF THIS PERIOD. THIS
FEATURE WILL INDUCE A SFC CYCLONE THAT IS FORECAST TO UNDERGO
SIGNIFICANT DEEPENING AS IT MOVES FROM THE UPPER MS VALLEY INTO THE
GREAT LAKES BY SUNDAY AFTERNOON. COLD FRONT TRAILING FROM THE LOW
WILL SWEEP THROUGH THE MID MS...OH AND TN VALLEYS...WHILE A WARM
FRONT LIFTS NWD THROUGH THE GREAT LAKES.

...OH AND TN VALLEYS AND GREAT LAKES REGIONS...

POTENTIAL EXISTS FOR A WIDESPREAD DAMAGING WIND EVENT AND A FEW
TORNADOES SUNDAY AFTERNOON AND NIGHT...ESPECIALLY IN AND NEAR THE
MODERATE RISK AREA ACROSS PARTS OF THE OH VALLEY AND GREAT LAKES.

CURRENT OBSERVATIONS SHOW DEWPOINTS RISING INTO THE MID 60S ALONG
COASTAL TX WITH 70 NOT FAR OFFSHORE. A STRONG 50+ KT SSWLY LLJ WILL
ADVECT PARTIALLY MODIFIED GULF AIR WITH LOW 60S DEWPOINTS AS FAR
NORTH AS THE OH VALLEY WITH MID 60S FARTHER SOUTH ACROSS THE TN
VALLEY. HOWEVER...THE MOISTURE RETURN WILL BE ACCOMPANIED BY
WIDESPREAD CLOUDS THAT WILL LIMIT DIABATIC WARMING IN MUCH OF THE
PRE-FRONTAL WARM SECTOR. IT STILL APPEARS PROBABLE THAT AREAS OF
SHOWERS AND A FEW THUNDERSTORMS WILL BE ONGOING ALONG WARM CONVEYOR
BELT SUNDAY MORNING. THUS...THE PRIMARY DESTABILIZATION MECHANISM
WILL BE LOW-LEVEL THETA-E ADVECTION BENEATH A PLUME OF EWD
DEVELOPING 7-7.5 MID-LEVEL LAPSE RATES. IN WAKE OF WARM ADVECTION
STORMS...AN AXIS OF MLCAPE FROM 500-1500 J/KG WILL LIKELY DEVELOP IN
PRE-FRONTAL WARM SECTOR.

THE DEEPENING CYCLONE WILL BE ACCOMPANIED BY AN INCREASE IN
FRONTOGENETIC FORCING ALONG THE COLD FRONT SWEEPING EWD THROUGH THE
GREAT LAKES AND OH VALLEY. STORMS MAY REDEVELOP BY AFTERNOON ALONG
PRE-FRONTAL WARM CONVEYOR BELT BENEATH DIFFLUENT UPPER JET EXIT
REGION AS THE ATMOSPHERE DESTABILIZES. SHOULD SFC BASED WARM SECTOR
INITIATION OCCUR...80+ KT MID-LEVEL WSWLY WINDS WILL PROMOTE FAST
MOVING STORMS THAT SHOULD REMAIN AHEAD OF ADVANCING COLD FRONT.
THESE STORMS WILL LIKELY BE DISCRETE WHERE LARGE HODOGRAPHS AND 50+
KT EFFECTIVE BULK SHEAR WILL PROMOTE SUPERCELLS CAPABLE OF PRODUCING
LARGE HAIL AND TORNADOES. HOWEVER...DEGREE OF THE TORNADO THREAT
/SHOULD THESE STORMS DEVELOP/ WILL DEPEND ON MAGNITUDE OF
DESTABILIZATION WITHIN THE WARM SECTOR BOUNDARY LAYER.

OTHERWISE...STORMS SHOULD INITIATE ALONG STRENGTHENING COLD FRONT
FROM THE GREAT LAKES SWWD INTO THE MID MS AND TN VALLEYS AND
SUBSEQUENTLY DEVELOP EWD. GIVEN STRENGTH OF VERTICAL SHEAR...THESE
STORMS WILL LIKELY EVOLVE INTO AN ORGANIZED LINEAR MCS WITH LEWP AND
BOW ECHO STRUCTURES CAPABLE OF PRODUCING WIDESPREAD DAMAGING WIND.
ISOLATED TORNADOES ASSOCIATED WITH EMBEDDED MESO-VORTICES ALSO WILL
BE POSSIBLE WITH THE SQUALL LINE.

...NERN U.S....

STORMS WILL EVENTUALLY OUTPACE THE AXIS OF RICHER LOW LEVEL MOISTURE
LATER SUNDAY NIGHT AND ENCOUNTER MUCH WEAKER INSTABILITY AS THEY
APPROACH THE NERN STATES. HOWEVER...SOME THREAT FOR DAMAGING WIND
MAY PERSIST WITH REMAINING LOW TOPPED CONVECTION LATE THIS PERIOD.

..DIAL.. 11/16/2013

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