DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 121722
SWODY2
SPC AC 121721

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1121 AM CST SAT DEC 12 2009

VALID 131200Z - 141200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
ALTHOUGH BROAD LONGWAVE TROUGH IS SITUATED OVER THE WRN TWO-THIRDS
OF NORTH AMERICA...PRIMARILY STRONG ZONAL FLOW WILL PERSIST OVER THE
CONUS THROUGH SUNDAY. HEIGHTS WILL RISE SLIGHTLY OVER THE SERN
STATES/MID ATLANTIC REGION DURING THE DAY...AS A SHORTWAVE TROUGH
MOVES EWD THROUGH THE OH VALLEY AND OFF THE NRN ATLANTIC COAST
SUNDAY NIGHT. INCREASING SLY LOW LEVEL WINDS WILL AID IN LIFTING A
SURFACE BOUNDARY NWD FROM THE GULF...AND SHOULD EXTEND ROUGHLY FROM
SRN MS/LA NEWD INTO THE ERN SC/NC DURING MUCH OF THE FORECAST
PERIOD.

FURTHER WEST...ANOTHER IMPULSE IS FORECAST TO SHIFT EWD FROM THE SRN
GREAT BASIN INTO THE SRN ROCKIES...AHEAD OF A STRONGER IMPULSE
DROPPING SEWD FROM CANADA INTO THE NRN ROCKIES. HOWEVER...SWD PUSH
OF ARCTIC AIR THROUGH THE PLAINS STATES INTO AN ALREADY STABLE AIR
MASS WILL INHIBIT CONVECTIVE DEVELOPMENT WITH THESE SYSTEMS.

...ERN CAROLINAS...
UPPER WAVE MOVING THROUGH THE OH VALLEY MAY INDUCE A WEAK WAVE ALONG
THE BOUNDARY IN THE ERN CAROLINAS SUNDAY MORNING/EARLY AFTERNOON.
SOUTH OF THIS BOUNDARY...MODIFIED GULF MOISTURE RETURN IS
EXPECTED...WITH DEWPOINTS IN THE LOWER TO MID 60S. SINCE THE
STRONGER LARGE SCALE ASCENT WILL BE LOCATED WELL NORTH OF THE
BOUNDARY...MOST PCPN WILL BE OCCUR IN THE COLD SECTOR. WHILE
CONVECTION IS POSSIBLE IN WARM SECTOR...DURING THE MORNING...
FORECAST SOUNDINGS SHOW TREMENDOUS LOW/DEEP LAYER SHEAR...BUT
UPDRAFTS ROOTED AROUND 850 MB. A WARMING BOUNDARY LAYER MAY RESULT
IN ANY STORM UPDRAFTS INGESTING SURFACE BASED PARCELS LATER IN THE
DAY. HOWEVER...VEERING LOW LEVEL WINDS/WEAKENING SHEAR...COMBINED
WITH NEUTRAL OR SLIGHTLY RISING HEIGHTS SUGGEST STRONGER
CONVERGENCE/STORMS WILL BE LOCATED EAST OF THE INLAND AREAS IN THE
ATLANTIC. THEREFORE...OVERALL SEVERE THREAT APPEARS LIMITED.

...GULF COAST THROUGH NRN FL...
WHILE WEAK INSTABILITY IS EXPECTED IN THE WARM SECTOR...VEERING LOW
LEVEL WINDS AND MASS CONVERGENCE...ALONG WITH NEUTRAL TO SLIGHTLY
RISING 500 MB HEIGHTS SHOULD DAMPEN THE THREAT FOR SEVERE STORMS.

..IMY.. 12/12/2009

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