Saturday, December 5, 2009

DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 050517
SWODY2
SPC AC 050516

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1116 PM CST FRI DEC 04 2009

VALID 061200Z - 071200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
TO THE SOUTHEAST OF A BUILDING UPPER HIGH CENTER OVER THE GULF OF
ALASKA AND ALASKA...MODELS INDICATE THAT A CLOSED LOW WILL GRADUALLY
EVOLVE ACROSS THE PACIFIC NORTHWEST/NORTHERN INTERMOUNTAIN REGION
THIS WEEKEND. THIS FEATURE MAY SHIFT WESTWARD A BIT ON SUNDAY...AS
A SIGNIFICANT SHORT WAVE IMPULSE PIVOTS AROUND ITS WESTERN PERIPHERY
ALONG PACIFIC NORTHWEST COASTAL AREAS.

TO THE SOUTH OF THE LOW...EASTWARD THROUGH THE ATLANTIC
SEABOARD...BROADLY CYCLONIC WEST SOUTHWESTERLY FLOW IS EXPECTED TO
PREVAIL...WITH AT LEAST A COUPLE OF EMBEDDED SHORT WAVE IMPULSES
ACCELERATING OUT OF THE CENTRAL/SOUTHERN ROCKIES AND MEXICAN PLATEAU
REGION. GUIDANCE INDICATES THAT THIS WILL BE ACCOMPANIED BY
STRENGTHENING SOUTHERLY LOW-LEVEL FLOW FROM THE SOUTHERN PLAINS
THROUGH THE LOWER MISSISSIPPI VALLEY SUNDAY. BUT...IT STILL APPEARS
LIKELY THAT GULF OF MEXICO BOUNDARY LAYER MODIFICATION WILL NOT BE
SUFFICIENT TO SUPPORT A SUBSTANTIVE MOISTURE RETURN... WITH LOW TO
NEGLIGIBLE POTENTIAL FOR BOUNDARY LAYER DESTABILIZATION INLAND OF
COASTAL AREAS...AND ACROSS THE COASTAL WATERS.

...PARTS OF THE MID TO LOWER MISSISSIPPI VALLEY...
ONE VIGOROUS SHORT WAVE IMPULSE/JET STREAK EMANATING FROM THE GREAT
BASIN IS PROGGED TO REACH THE OZARK PLATEAU BY SUNDAY
EVENING...BEFORE CONTINUING INTO LOWER OHIO VALLEY BY 12Z MONDAY.
AS ASSOCIATED FORCING INTERACTS WITH A ZONE OF ENHANCED ISENTROPIC
ASCENT ASSOCIATED WITH LOWER/MID TROPOSPHERIC WARM ADVECTION...
THERMODYNAMIC PROFILES MAY BECOME SUPPORTIVE OF CONVECTIVE
DEVELOPMENT IN THE PRESENCE OF WEAK ELEVATED MOISTURE RETURN.
VARIABILITY EXISTS AMONG THE MODELS CONCERNING THE POTENTIAL FOR
THUNDERSTORM DEVELOPMENT...BUT IT SEEMS PROBABILITIES ARE AT LEAST
MARGINALLY SUFFICIENT FOR A CATEGORICAL THUNDERSTORM OUTLOOK ACROSS
PARTS OF EASTERN ARKANSAS/SOUTHEAST MISSOURI INTO WESTERN
KENTUCKY/TENNESSEE AND NORTHWEST MISSISSIPPI DURING THE 07/03-09Z
TIME FRAME.

..KERR.. 12/05/2009

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