DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 070532
SWODY1
SPC AC 070530

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1130 PM CST FRI DEC 06 2013

VALID 071200Z - 081200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
WHILE MID-LEVEL SUBTROPICAL RIDGING REMAINS FAIRLY STRONG ACROSS THE
SOUTHERN AND EASTERN GULF OF MEXICO...EASTWARD TO INTO THE WESTERN
ATLANTIC...COLD UPPER TROUGHING IS EXPECTED TO PERSIST ACROSS MUCH
OF THE WESTERN INTO CENTRAL U.S...DOWNSTREAM OF A BLOCKED REGIME
ACROSS THE NORTHEAST PACIFIC. A SIGNIFICANT SHORT WAVE TROUGH
WITHIN THE CYCLONIC FLOW OVER THE WEST IS FORECAST TO TURN EASTWARD
ACROSS THE GREAT BASIN AND CENTRAL ROCKIES DURING THIS FORECAST
PERIOD. THE APPROACH OF THIS LATTER FEATURE APPEARS LIKELY TO
CONTRIBUTE TO SUBSTANTIAL SURFACE PRESSURE FALLS ACROSS MUCH OF THE
PLAINS LATER TODAY INTO TONIGHT. HOWEVER...SEASONABLY COLD AIR IS
EXPECTED TO REMAIN ENTRENCHED ACROSS MOST AREAS EAST OF THE ROCKIES.
THE SHALLOW LEADING EDGE OF THIS AIR MASS HAS YET TO REACH PORTIONS
OF THE EASTERN GULF AND SOUTH ATLANTIC COAST STATES...BUT IT HAS
ADVANCED ACROSS THE APPALACHIANS INTO NORTHERN MID ATLANTIC COASTAL
AREAS...AND SOUTHWARD PROGRESSION ASSOCIATED WITH DAMMING TO THE
EAST OF THE SOUTHERN APPALACHIANS IS EXPECTED TO PROCEED THROUGH THE
DAY. AT THE SAME TIME...A SOUTHERLY RETURN FLOW OF MOISTURE OFF THE
GULF OF MEXICO INTO MUCH OF THE SOUTHEAST IS EXPECTED TO
CONTINUE...ON THE WESTERN PERIPHERY OF LOW-LEVEL RIDGING ASSOCIATED
WITH THE MID-LEVEL SUBTROPICAL RIDGE.

IN RESPONSE TO THE EVOLVING LARGE-SCALE PATTERN...GENERALLY STABLE
CONDITIONS WITH LOW TO NEGLIGIBLE CONVECTIVE POTENTIAL SHOULD
PERSIST ACROSS MUCH OF THE NATION. THE PRIMARY EXCEPTION MAY BE
TOWARD THE END OF THE PERIOD ACROSS PARTS OF THE TENNESSEE VALLEY
AND ADJACENT MID-SOUTH...WHERE LOW-LEVEL MOISTURE RETURN WITHIN A
ZONE OF STEEPENING ISENTROPIC ASCENT MAY CONTRIBUTE TO CONDITIONAL
AND CONVECTIVE INSTABILITY SUPPORTIVE OF SCATTERED WEAK THUNDERSTORM
ACTIVITY...ABOVE THE LINGERING SHALLOW COLD/STABLE LAYER BASED AT
THE SURFACE.

..KERR/ROGERS.. 12/07/2013

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