DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 181232
SWODY1
SPC AC 181229

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0629 AM CST WED DEC 18 2013

VALID 181300Z - 191200Z

...NO TSTM AREAS FORECAST...

...SYNOPSIS...
UPPER-AIR PATTERN FCST TO TRANSITION FROM ONE DOMINATED BY ERN CONUS
TROUGHING TO WRN CONUS TROUGHING...WITH ISOHYPSIC PIVOT POINT OR
ISALLOHYPSIC ZERO LINE GENERALLY NEAR MS RIVER FOR MOST OF PERIOD.
SHORTWAVE TROUGHS AND SPEED MAX ALOFT -- NOW EVIDENT IN MOISTURE
CHANNEL IMAGERY OVER AK PANHANDLE...BC COAST AND ADJOINING NERN PAC
WATERS -- ARE FCST TO DIG SSEWD ALONG CONUS PAC COAST THROUGH END OF
PERIOD. AS HEIGHTS FALL AND GRADIENT ALOFT TIGHTENS AHEAD OF
COASTAL AMPLIFICATION REGIME...WELL-DEFINED SHORTWAVE TROUGH NOW
OFFSHORE CA WILL ACCELERATE INLAND AND WEAKEN CONSIDERABLY ACROSS
SRN CA. NET RESULT WILL BE BROAD AREA OF CYCLONIC FLOW COVERING WRN
CONUS BY 12Z.

AT SFC...CYCLONE NOW OVER SRN AK IS FCST TO MOVE SEWD OVER NRN
PLAINS THEN EWD OVER UPPER GREAT LAKES THROUGH PERIOD...WHILE
RELATED COLD FRONT SURGES SWD ACROSS NRN PLAINS. BY 12Z...FRONT
SHOULD EXTEND FROM LOW OVER ONT -- N OF LH -- SWWD ACROSS IA TO
SECONDARY LOW OF HYBRID LEE-SIDE/FRONTAL-WAVE CHARACTER OVER SWRN
KS/SERN CO REGION. LEE TROUGH WILL EXTEND FROM THAT LOW SSWWD
ACROSS SRN HIGH PLAINS.

WHILE LOW-LEVEL WAA AND EARLY-STAGE MOISTURE RETURN WILL BE UNDERWAY
OVER SRN PLAINS AND OZARKS REGION BY END OF PERIOD...AIR MASS WILL
REMAIN TOO DRY AND/OR STABLE TO SUPPORT GEN THUNDER THREAT OVER
CONUS.

..EDWARDS/MARSH.. 12/18/2013

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