SPC AC 230714
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0114 AM CST SUN DEC 23 2007
VALID 251200Z - 261200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
MODEL GUIDANCE IS CONSISTENT INDICATING A CONTINUED PROGRESSION OF
STRONG UPPER TROUGHS DIGGING SEWD FROM THE NORTHWESTERN STATES INTO
THE CENTRAL AND SRN PLAINS DURING THE DAY 3 PERIOD...AS THE NEXT IN
A SERIES OF UPSTREAM PACIFIC TROUGHS MOVES INTO THE PACIFIC NW. THE
PRIMARY SURFACE LOW IS EXPECTED TO DEVELOP OVER NRN ONTARIO AND MOVE
TOWARD JAMES BAY...WITH A TRAILING COLD FRONT EXTENDING FROM THE
UPPER MS VALLEY INTO THE SRN PLAINS DURING THE AFTERNOON BEFORE
REACHING A LINE FROM THE UPPER GREAT LAKES/MIDDLE MS VALLEY/LOWER TX
COAST BY THE END OF THE PERIOD.
...SRN/ERN TX INTO NWRN LA AND AR...
A WEAK RETURN FLOW CYCLE IS FORECAST TO BECOME ESTABLISHED OVER THE
NWRN GULF OF MEXICO COASTAL REGION...BUT LONG EASTERLY TRAJECTORIES
ACROSS THE COOLER WATERS OF THE NRN GULF ARE EXPECTED TO LIMIT THE
MAGNITUDE OF THE INLAND MOISTURE RETURN. NAM...GFS...AND MOST SREF
MEMBERS INDICATE SURFACE DEW POINTS IN THE UPPER 40S TO LOWER 50S
WILL SPREAD INTO PARTS OF SRN/ERN TX AND POSSIBLY SRN LA IN ADVANCE
OF THE APPROACHING COLD FRONT. MODEL SOUNDINGS INDICATE THAT
INSTABILITY WILL BE FURTHER LIMITED BY A PRONOUNCED INVERSION BASED
IN THE 850-750 MB LAYER...WITH A NARROW REGION OF MARGINAL
INSTABILITY /MUCAPE AOB 250 J/KG/ POSSIBLY DEVELOPING ALONG OR
IMMEDIATELY BEHIND THE COLD FRONT DURING THE LATTER HALF OF THE
PERIOD. THIS SUGGESTS A POSSIBILITY OF ISOLATED THUNDERSTORMS
DEVELOPING FROM PARTS OF AR SWWD INTO SRN/ERN TX. DESPITE STRONG
DEEP LAYER VERTICAL SHEAR OVER THE AREA...UNFAVORABLE THERMODYNAMIC
PROFILES/LIMITED INSTABILITY SUGGEST SEVERE THUNDERSTORMS ARE NOT
LIKELY.
..WEISS.. 12/23/2007
CLICK TO GET WUUS03 PTSDY3 PRODUCT
NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 1100Z
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