DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 201238
SWODY1
SPC AC 201236

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0736 AM CDT SUN OCT 20 2013

VALID 201300Z - 211200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
AN INITIAL SHORTWAVE TROUGH WILL PIVOT QUICKLY NEWD OVER SRN QUEBEC
THIS MORNING. WARMING ALOFT WILL REDUCE INSTABILITY OVER THE LOWER
GREAT LAKES...BRINGING AN END TO THE LIGHTNING RISK WITH THE LAKE
EFFECT BANDS OVER ERIE/ONTARIO. A STRONG UPSTREAM SHORTWAVE TROUGH
OVER MANITOBA WILL THEN ROTATE SSEWD TO THE UPPER MS VALLEY BY EARLY
MONDAY...WITHIN THE LARGER-SCALE TROUGH OVER THE PLAINS/MS
VALLEY/GREAT LAKES. AN ASSOCIATED SURFACE CYCLONE IS FORECAST TO
DEVELOP ESEWD FROM THE ERN DAKOTAS TO WI TODAY...AND THEN NEWD TO
ERN UPPER MI BY 12Z MONDAY. AS THIS SYSTEM CROSSES LAKE MI
TONIGHT...WEAK BUOYANCY WILL DEVELOP IN RESPONSE TO
ASCENT/STEEPENING LAPSE RATES OVER THE RELATIVELY WARM LAKE
WATERS...SUPPORTING A RISK FOR ISOLATED THUNDERSTORMS.

A SEPARATE/LOWER-AMPLITUDE SHORTWAVE TROUGH OVER THE NRN HIGH PLAINS
WILL PROGRESS SEWD TO THE CENTRAL PLAINS. RELATED LEE CYCLOGENESIS
ACROSS THE SRN HIGH PLAINS WILL INDUCE SLY LOW-LEVEL FLOW AND
MOISTURE RETURN ACROSS TX/OK BY TONIGHT. ISOLATED THUNDERSTORMS
WILL BE POSSIBLE OVER THE HIGHER TERRAIN OF THE TX BIG BEND WHERE
STRONG SURFACE HEATING WILL OCCUR ON THE NW EDGE OF THE INITIAL
MOISTURE RETURN UP THE RIO GRANDE VALLEY. BY TONIGHT...THE
MOISTENING ABOVE THE SURFACE SHOULD BE SUFFICIENT FOR AT LEAST WEAK
BUOYANCY ROOTED IN THE 850-700 MB LAYER AFTER 06Z...WHEN ASCENT WITH
LOW-LEVEL WAA WILL SUPPORT ELEVATED THUNDERSTORM DEVELOPMENT FROM
THE RED RIVER VALLEY TO CENTRAL OK. THE NWD RETURN OF THE RICHER
TROPICAL MOISTURE OVER THE WRN GULF OF MEXICO TO S TX BY TONIGHT
WILL ALSO SUPPORT A RISK FOR ISOLATED THUNDERSTORMS. OTHERWISE...A
FEW DIURNAL THUNDERSTORMS ARE EXPECTED WITHIN THE MOIST PRE-FRONTAL
ENVIRONMENT ACROSS CENTRAL/S FL.

..THOMPSON/GARNER.. 10/20/2013

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