DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 210542
SWODY1
SPC AC 210540

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1240 AM CDT MON OCT 21 2013

VALID 211200Z - 221200Z

...NO SVR TSTM AREAS FORECAST...

...DISCUSSION...
A HIGHLY AMPLIFIED LONGWAVE PATTERN WILL EXIST OVER THE CONUS WITH
AN EAST-SOUTHEAST PIVOTING UPPER TROUGH OVER THE GREAT LAKES REGION
AND OH VALLEY/MIDDLE MS RIVER VALLEY...WHILE AN UPPER RIDGE REMAINS
PREVALENT OVER THE WESTERN STATES. THE PRIMARY COLD FRONT WILL
ADVANCE SOUTHEASTWARD ACROSS THE LOWER GREAT LAKES/OH
VALLEY...LOWER-MIDDLE MS RIVER VALLEY...AND ARKLATEX/PORTIONS OF TX
DURING THE PERIOD...WHERE IT WILL INTERCEPT A RELATIVELY MOIST
AIRMASS /LOWER 60S F SURFACE DEWPOINTS/ ACROSS SOUTH/EAST TX AND
OTHER PARTS OF THE ARKLATEX. IN GENERAL...RELATIVELY LIMITED
MOISTURE/INSTABILITY WILL HINDER TSTM POTENTIAL ACROSS THE CONUS
EXCEPT AS SUBSEQUENTLY DETAILED.

ACROSS THE UPPER GREAT LAKES IN VICINITY OF THE UPPER TROUGH COLD
CORE...LOW-TOPPED UPDRAFTS MAY ATTAIN SUFFICIENT DEPTH FOR CHARGE
SEPARATION LATER TODAY...WITH A FEW TSTMS POSSIBLE THIS AFTERNOON
INTO TONIGHT. OTHER TSTMS WILL BE POSSIBLE ACROSS FL IN VICINITY OF
THE REMNANT FRONT/AFTERNOON SEA BREEZE. ADDITIONALLY...A FEW STRAY
LIGHTNING STRIKES MIGHT BE POSSIBLE THIS AFTERNOON/EVENING ACROSS
THE NORTH-CENTRAL PLAINS IN VICINITY OF A SURFACE LOW/SECONDARY
FRONT...BUT OVERALL TSTM POTENTIAL CURRENTLY APPEARS BELOW 10
PERCENT.

...SOUTH TX...
A FEW STRONGER STORMS POTENTIALLY CAPABLE OF MARGINAL HAIL/LOCALLY
DAMAGING WINDS CANNOT BE ENTIRELY DISCOUNTED THIS AFTERNOON WITHIN A
MOIST/MODERATELY UNSTABLE ENVIRONMENT NEAR THE ADVANCING COLD FRONT.
HOWEVER...THE SEVERE POTENTIAL CURRENTLY APPEARS LOW GIVEN FACTORS
SUCH AS MODEST MID-LEVEL LAPSE RATES AND A TREND TOWARD WEAKENING
CONVERGENCE NEAR THE COLD FRONT LATER TODAY.

..GUYER/COHEN.. 10/21/2013

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