DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 111731
SWODY2
SPC AC 111729

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1129 AM CST FRI JAN 11 2013

VALID 121200Z - 131200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM E TX...CENTRAL/NRN LA INTO
AR...

...SYNOPSIS...
A DEEP...POSITIVE-TITLED LONGWAVE TROUGH WILL BE MAINTAINED ON
SATURDAY FROM BAJA/SWRN STATES TO CENTRAL CANADA...AS A STRONG RIDGE
CONTINUES TO BUILD NWD INTO ERN AK AND A RIDGE BUILDS NWD ALONG THE
ATLANTIC COAST. A BAND OF STRONG MID AND UPPER LEVEL SWLY WINDS
DEVELOPING FROM THE SWRN STATES INTO THE UPPER MS VALLEY DURING DAY
1 WILL PERSIST THROUGH DAY 2...BUT SHIFT EWD EXTENDING FROM THE SRN
PLAINS TO THE GREAT LAKES ON SATURDAY. A STRONG SHORTWAVE
TROUGH...CURRENTLY LOCATED OVER THE FOUR CORNERS...WILL REMAIN
PROGRESSIVE TRACKING FROM THE UPPER MS VALLEY THROUGH ONTARIO AND
QUEBEC. MEANWHILE...AN UPSTREAM SHORTWAVE TROUGH WILL EMERGE FROM
NRN BAJA/SONORA INTO THE SRN PLAINS SATURDAY AFTERNOON AND REACH THE
UPPER MS VALLEY/WRN GREAT LAKES BY 12Z SUNDAY.

AT THE SURFACE...A COLD FRONT ATTENDANT TO THE LEAD SHORTWAVE TROUGH
IS EXPECTED TO EXTEND FROM THE UPPER GREAT LAKES SSWWD THROUGH THE
MID MS VALLEY TO CENTRAL TX. THIS FRONT WILL ADVANCE EWD THROUGH THE
GREAT LAKES...THE LOWER OH/TN/MS VALLEYS...AND TOWARD THE TX COAST
BY 12Z SUNDAY.

...E TX/CENTRAL AND NRN LA/SRN AND CENTRAL AR...
12Z MODELS REMAIN IN AGREEMENT SHOWING A SURFACE LOW ATTENDANT TO
THE NRN SONORA TROUGH WILL DEVELOP OVER SOUTH CENTRAL TX AND TRACK
NEWD ALONG THE FRONTAL ZONE...WITH THE LOW REACHING THE ARKLATEX
REGION BY 13/00Z. POTENTIAL EXISTS FOR RELATIVELY STRONG DEEPENING
OF THIS LOW WHEN IT MOVES INTO NERN TX/SWRN AR SATURDAY AFTERNOON.
STRONG UPWARD VERTICAL ASCENT SHOULD BE UNDERWAY IN THAT REGION DUE
TO UPPER LEVEL JET COUPLING ATOP A STRENGTHENING SSWLY LLJ INTO THE
FRONTAL ZONE.

SLY LOW LEVEL FLOW INTO CENTRAL/ERN TX AND THE LOWER MS VALLEY
DURING THE LATTER HALF OF DAY 1 WILL PERSIST INTO DAY 2 ACROSS THE
WARM SECTOR WITH SURFACE DEWPOINTS EXPECTED TO BE IN THE MID-UPPER
60S. THIS DESTABILIZATION WILL INCREASE SATURDAY AS STEEPENING
MIDLEVEL LAPSE RATES SPREAD NEWD ATOP THE MOISTURE RETURN WITH
MLCAPES OF 500-1000 J/KG. GIVEN THIS INSTABILITY AND FORECAST FOR
STRENGTHENING DEEP LAYER WINDS AND DEEP SHEAR ACROSS THE SLIGHT RISK
AREA...THE POTENTIAL WILL EXIST FOR ORGANIZED STORMS INCLUDING A FEW
SUPERCELLS INVOF AND E OF THE FRONT. ALTHOUGH INSTABILITY WILL
WEAKEN SATURDAY EVENING/OVERNIGHT...MODELS SUGGEST A QLCS SHOULD
ADVANCE ESEWD TOWARD THE LOWER MS VALLEY AND TX GULF COAST.

..PETERS.. 01/11/2013

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