DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 171228
SWODY1
SPC AC 171225

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0625 AM CST TUE DEC 17 2013

VALID 171300Z - 181200Z

...NO TSTM AREAS FORECAST...

...SYNOPSIS...
UPPER-AIR PATTERN FCST TO BECOME LESS AMPLIFIED THROUGH PERIOD AS
RIDGING OVER CA DEAMPLIFIES CONSIDERABLY...AND SYNOPTIC-SCALE TROUGH
NOW OVER GREAT LAKES AND OH VALLEY MOVES EWD/WEAKENS. SHORTWAVE
TROUGH AND ACCOMPANYING SPEED MAX ALOFT -- NOW EVIDENT IN MOISTURE
CHANNEL IMAGERY OVER UPPER MS VALLEY REGION -- ARE FCST TO PIVOT
SEWD/EWD OVER WV/VA/TN APPALACHIANS BY 00Z THEN WEAKEN AND MOVE
OFFSHORE MID-ATLC REGION BY END OF PERIOD.

AT SFC...HIGH AND ACCOMPANYING ANTICYCLONE WILL DEVELOP OVER CENTRAL
PLAINS AND MOVE/EXPAND SEWD ACROSS MID-SOUTH REGION. THIS PROCESS
WILL REINFORCE LOW-THETAE OFFSHORE TRAJECTORIES ACROSS MOST OF
CENTRAL/ERN GULF AND FL...RESTRICTING RETURN-FLOW MOISTURE AND
PRECLUDING TSTM THREAT OVER MOST OF CONUS E OF ROCKIES. APCHG
TROUGH WILL SUPPORT SFC CYCLOGENESIS THIS AFTN FROM COASTAL MID-ATLC
TO NEAR SRN NEW ENGLAND COAST...WITH COLD FRONTOGENESIS SWWD INTO
APPALACHIANS. RESULTING COLD FRONT SHOULD MOVE COMPLETELY OFFSHORE
MID-ATLC/TIDEWATER REGION BY 06Z.

...CENTRAL APPALACHIANS TO TIDEWATER...
LARGE-SCALE ASCENT RELATED TO SHORTWAVE TROUGH...COMBINED WITH MRGL
LOW-LEVEL MOISTURE...MAY SUPPORT PRIMARILY SHALLOW CONVECTION OVER
THIS REGION THIS AFTN AND EVENING...ALONG AND BEHIND SFC COLD FRONT.
DESPITE STEEPENED LOW-MIDDLE LEVEL LAPSE RATES AND MUCAPE UP TO 100
J/KG...PRIND MOST BUOYANCY PROFILES WILL REMAIN TOO SHALLOW AND WEAK
IN MAGNITUDE FOR THUNDER. WHILE VERY BRIEF/ISOLATED LTG CANNOT BE
RULED OUT...POTENTIAL APPEARS TOO LOW/CONDITIONAL FOR GEN TSTM AREA.
GREATER COVERAGE OF TSTMS MAY DEVELOP WELL OFFSHORE THIS AFTN AND
OVERNIGHT AS STRONGER DEEP-LAYER ASCENT AND FRONTAL FORCING
OVERSPREAD GULF STREAM WATERS.

..EDWARDS/MARSH.. 12/17/2013

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