DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 271247
SWODY1
SPC AC 271244

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0744 AM CDT SUN OCT 27 2013

VALID 271300Z - 281200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
IN MID-UPPER LEVELS...BROAD AREA OF CYCLONIC FLOW WILL COVER ERN
CONUS EARLY IN PERIOD...THOUGH RELATED SYNOPTIC TROUGHING SHOULD
DEAMPLIFY WITH TIME. SHORTWAVE PERTURBATION INITIALLY OVER ARKLATEX
REGION EXHIBITS PRONOUNCED MID-UPPER LEVEL DRY SLOT OVER CENTRAL-E
TX. TROUGH SHOULD MOVE ESEWD ACROSS LOWER MS VALLEY TO AL AND
CENTRAL GULF COAST THROUGH REMAINDER PERIOD...WHILE GRADUALLY
WEAKENING. ASSOCIATED SFC FRONTAL ZONE FROM KY TO SW TX WILL LOSE
DEFINITION AS UPPER SYSTEM DEPARTS...AND AS GREATER CONTRIBUTION TO
REGIONAL BAROCLINICITY CONTINUES TO ARISE FROM MESOSCALE CONVECTIVE
PROCESSES.

MEANWHILE...STG SHORTWAVE TROUGH -- NOW EVIDENT IN MOISTURE CHANNEL
IMAGERY OVER BC -- IS FCST TO EXPERIENCE INTENSE AMPLIFICATION
THROUGH PERIOD AS IT DIGS SWD ACROSS NWRN CONUS. NET RESULT BY 12Z
SHOULD BE LARGE...CLOSED 500-MB CYCLONE CENTERED OVER NERN NV...WITH
RELATED CYCLONIC FLOW COVERING MOST OF WRN CONUS FROM ROCKIES WWD.
STG DCVA AND WAA WILL PRECEDE THIS SYSTEM...WITHIN REGIME OF
PRONOUNCED HEIGHT FALLS. STEEPENED MIDLEVEL LAPSE RATES AND MRGL
LOW-MIDDLE LEVEL MOISTURE MIGHT BE SUFFICIENT TO YIELD LOW-CAPE
CONVECTION APCHG ICING LAYERS SUITABLE FOR LTG PRODUCTION. AS
SUCH...A FEW LTG STRIKES CANNOT BE RULED OUT SOMEWHERE ACROSS BROAD
SWATH OF CENTRAL/NRN GREAT BASIN REGION OR SRN ID.
HOWEVER...LOW-LEVEL THETAE WILL REMAIN WEAK...AND COVERAGE/DURATION
OF ANY THUNDER THREAT APPEAR TOO SPARSE TO ASSIGN SPECIFIC AREA OF
AOA 10% TSTM RISK ATTM.

...MID-SOUTH/DELTA REGION...S TX...
MCS WITH EMBEDDED STG TSTMS IS EVIDENT FROM UPPER TX COAST WNWWD
ACROSS PORTIONS S-CENTRAL TX...AND IS PRECEDED BY SERIES OF GUST
FRONTS PER RADAR REFLECTIVITY ANIMATIONS. WHILE ISOLATED GUSTS
APCHG SVR LEVELS ARE POSSIBLE WITH THIS ACTIVITY...OVERALL THREAT
APPEARS TOO LOW AND CONDITIONAL TO ASSIGN PROBABILITIES ATTM...GIVEN

1. OFFSHORE MOTION OF MOST INTENSE PART ONGOING...
2. DEPARTURE OF MID-UPPER WAVE AWAY FROM AREA...LEADING TO HEIGHT
RISES AND WEAKENING OF BOTH LOW-LEVEL AND DEEP SHEAR...AND
3. CONTINUED ADVECTION FROM MEX PLATEAU OF ELEVATED MIXED-LAYER AIR
CAPPING BOUNDARY LAYER...WHICH WILL FORTIFY THAT CONTRIBUTION TO
CINH. STABLE LAYERS ALOFT WERE EVIDENT IN 12Z RAOBS FROM
LCH...CRP...BRO AND DRT.

STILL...THREAT FOR AT LEAST ISOLATED TO WIDELY SCATTERED TSTMS
SHOULD LINGER THROUGH AT LEAST LATE AFTN ALONG RESULTING
OUTFLOW/DIFFERENTIAL HEATING BOUNDARY...UNTIL BOUNDARY BECOMES TO
WEAK/SHALLOW TO PROVIDE FAVORABLE LIFT.

FARTHER N...WIDELY SCATTERED TO ISOLATED TSTMS ARE POSSIBLE LATE
MORNING THROUGH AFTN...IN REGIME OF DCVA...WEAKENING FRONTAL FORCING
AND MRGL LOW-LEVEL THETAE PRECEDING MID-UPPER SHORTWAVE TROUGH. GEN
TSTM AREA HAS BEEN BIFURCATED IN BETWEEN THESE TWO REGIMES...WHERE
COMBINATION OF DRY-SLOTTING/STABILIZATION ALOFT AND WEAK LOW-LEVEL
INSTABILITY WILL PREVAIL.

..EDWARDS/COHEN.. 10/27/2013

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@LISTSERV.ILLINOIS.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.