DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 131953
SWODY1
SPC AC 131951

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0251 PM CDT SAT OCT 13 2012

VALID 132000Z - 141200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE MID AND LOWER MO
VALLEY SWWD INTO TX...

...MID AND LOWER MO VALLEY SSWWD ACROSS THE SRN PLAINS...
THE ONGOING FORECAST REMAINS GENERALLY ON TRACK...WITH THE MAIN
CHANGES THIS FORECAST BEING A CONTINUED TREND TOWARD SWWD SHIFTING
OF THE PROBABILITIES. WHILE CLOUDS AND EARLIER PRECIPITATION HAVE
HINDERED SEVERE WEATHER POTENTIAL ACROSS NRN PORTIONS OF THE OUTLOOK
-- I.E. INTO PARTS OF NEB/IA/IL AND VICINITY...MORE FAVORABLE
CONDITIONS REMAIN FARTHER SW -- PARTICULARLY INTO THE OK/TX AREA.
HERE...MODERATE DESTABILIZATION /MIXED-LAYER CAPE 1500 TO 2000 J/KG/
HAS SUPPORTED A BAND OF VIGOROUS CONVECTIVE DEVELOPMENT FROM NRN/WRN
OK SWWD INTO NWRN TX. WITH AREA VWP/PROFILER DATA REVEALING SHEAR
SUPPORTIVE OF SUPERCELLS...THREAT FOR LARGE HAIL AND LOCALLY
DAMAGING WINDS ALONG WITH A COUPLE OF TORNADOES REMAINS EVIDENT.
SOME SWWD EXPANSION OF THE HIGHER PROBABILITY LINES -- PARTICULARLY
THE 30% HAIL LINE -- HAS BEEN IMPLEMENTED THIS FORECAST AS A RESULT
OF THESE TRENDS.

OTHERWISE...EXPECT THE THREAT AREA TO SHIFT EWD WITH TIME THIS
AFTERNOON AND EVENING...AS THE LARGE-SCALE SYSTEM MAKES STEADY
PROGRESS ACROSS THE CENTRAL CONUS.

..GOSS.. 10/13/2012

.PREV DISCUSSION... /ISSUED 1124 AM CDT SAT OCT 13 2012/

...SRN PLAINS TO THE MID MS VALLEY THROUGH TONIGHT...
A PRONOUNCED SHORTWAVE TROUGH IS EMERGING OVER ERN CO/NM AS OF MID
MORNING...AND THIS WAVE IS EXPECTED TO DEVELOP A MORE NEUTRAL TILT
AS IT PROGRESSES EWD OVER KS/OK THROUGH ABOUT 06Z. SURFACE
CYCLOGENESIS WILL OCCUR ACROSS CENTRAL/NRN KS BY ABOUT 00Z...AND
THIS LOW WILL CONTINUE ENEWD ACROSS NRN MO/SRN IA OVERNIGHT. THE
WARM SECTOR WILL EXPAND NWD SOME IN ADVANCE OF THE LOW...WHILE A
TRAILING COLD FRONT MOVES EWD INTO WRN OK AND CENTRAL KS BY THIS
EVENING.

ONGOING ELEVATED CONVECTION WILL PERSIST THROUGH THE AFTERNOON FROM
CENTRAL/N TX NNEWD ACROSS CENTRAL/ERN OK TO ERN KS/WRN MO...WHICH
WILL LIMIT INSTABILITY THIS AFTERNOON IN AREAS IMMEDIATELY
DOWNSTREAM FROM THESE STORMS. GIVEN THE GRADUAL INCREASE IN
VERTICAL SHEAR AND SOME DESTABILIZATION IN THE BOUNDARY LAYER
IMMEDIATELY AHEAD OF THE CONVECTION FROM CENTRAL TX INTO ERN
OK...THERE WILL BE SOME POTENTIAL FOR EMBEDDED SUPERCELL STRUCTURES
THIS AFTERNOON WITH AN ATTENDANT RISK FOR ISOLATED DAMAGING GUSTS
AND PERHAPS A TORNADO. HOWEVER...THE PRIMARY SEVERE STORM RISK WILL
DEVELOP LATER THIS AFTERNOON/EVENING ALONG THE SYNOPTIC COLD FRONT
FARTHER TO THE W ACROSS WRN/CENTRAL OK AND CENTRAL KS. BOUNDARY
LAYER DEWPOINTS IN THE MID-UPPER 60S WILL BE MAINTAINED ACROSS THIS
AREA WHERE CLOUD BREAKS THIS AFTERNOON...IN THE WAKE OF THE MORNING
CONVECTION...WILL BOOST MLCAPE VALUES TO NEAR 2000 J/KG.

ADDITIONAL THUNDERSTORM DEVELOPMENT IS EXPECTED IN THE 22-00Z TIME
FRAME AS ASCENT WITH THE MIDLEVEL TROUGH PHASES WITH LOW-LEVEL
ASCENT ALONG THE COLD FRONT. LINE SEGMENTS APPEAR TO BE A LIKELY
CONVECTIVE MODE OUTCOME IN KS AS A RESULT OF LINEAR ASCENT AND
LARGELY FRONT-PARALLEL WINDS/SHEAR VECTORS. THE CROSS-FRONTAL SHEAR
WILL BE STRONGER IN OK/N TX...WHERE A MIXED MODE OF LINE SEGMENTS
AND EMBEDDED SUPERCELLS IS PROBABLE. THE COMBINATION OF MODERATE
INSTABILITY...A MOIST BOUNDARY LAYER...EFFECTIVE BULK SHEAR AOA 50
KT...AND EFFECTIVE SRH NEAR 300 M2/S2 ALL APPEAR SUPPORTIVE OF
SUPERCELL TORNADO RISK...WITH CONVECTIVE MODE BEING THE PRIMARY
POTENTIAL LIMITING FACTOR. OTHERWISE...THE INITIAL STORMS WILL BE
CAPABLE OF PRODUCING LARGE HAIL AND DAMAGING WINDS...AND THE
DAMAGING WIND THREAT SHOULD PERSIST INTO TONIGHT AS THE BANDS OF
FRONTAL CONVECTION SPREAD EWD.

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
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.