SWODY2
SPC AC 201727
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1227 PM CDT SUN SEP 20 2009
VALID 211200Z - 221200Z
...THERE IS A SLGT RISK OF SVR TSTMS CNTRL AND SRN PLAINS...MID-MO
VALLEY...
...SRN AND CNTRL PLAINS/LOWER TO MID-MO VALLEY...
A HIGH AMPLITUDE UPPER-LEVEL TROUGH WILL DIG SEWD INTO THE CNTRL
HIGH PLAINS MONDAY. AT THE SFC...A SHARPLY-DEFINED COLD FRONT IS
FORECAST TO MOVE SEWD INTO THE MID-MO VALLEY AND SRN PLAINS. A
CLUSTER OF ELEVATED THUNDERSTORMS MAY BE ONGOING ALONG THE BOUNDARY
IN ERN NEB AND/OR ERN KS MONDAY MORNING ASSOCIATED WITH EXIT REGION
OF A 40-50 KT LOW-LEVEL JET. AHEAD OF THE FRONT...FORECAST SOUNDINGS
SHOW A STRONGLY CAPPED WARM SECTOR UNTIL EARLY TO MID-AFTERNOON WHEN
SFC-BASED THUNDERSTORMS WILL LIKELY DEVELOP ALONG THE FRONT. THE
NAM/ETA-KF SOLUTIONS DEVELOP THE FIRST SFC-BASED STORMS IN SERN KS
WITH THE GFS FOCUSED FURTHER WEST ALONG THE I-135 CORRIDOR. THE
MODELS DO AGREE WITH RAPID EXPANSION OF NUMEROUS THUNDERSTORMS FROM
ERN KS SSWWD ACROSS CNTRL OK AND NORTH TX BY LATE AFTERNOON. AN MCS
APPEARS LIKELY ACROSS MUCH OF THE SLIGHT RISK AREA WITH STORMS
PERSISTING EWD INTO THE NRN AND WRN OZARKS SWWD INTO NE TX DURING
THE OVERNIGHT PERIOD.
CONCERNING THE POTENTIAL FOR ORGANIZED STORMS...FORECAST SOUNDINGS
ACROSS THE REGION AHEAD OF THE FRONT SHOW GRADUALLY VEERING WIND
PROFILES BELOW 700 MB WITH SOME SPEED SHEAR IN THE MID-LEVELS. THIS
SHOULD PRODUCE 0-6 KM SHEAR VALUES IN THE 25-35 KT RANGE WHICH WILL
LIKELY BE SUFFICIENT FOR SCATTERED SEVERE STORMS. ALTHOUGH ISOLATED
SEVERE STORMS WILL BE POSSIBLE FROM SRN IA SSWWD ACROSS WRN MO INTO
ERN KS...THE GREATER INSTABILITY AND STEEPER MID-LEVEL LAPSE RATES
ARE FORECAST ACROSS THE SRN PLAINS. IN THIS AREA...MODERATE
INSTABILITY COULD OVERCOME THE MARGINAL VERTICAL SHEAR FOR ISOLATED
SUPERCELL DEVELOPMENT. ANY SUPERCELL THAT CAN ORGANIZE WILL LIKLEY
HAVE A THREAT FOR LARGE HAIL. AS THE EVENT UNFOLDS...THE SUPERCELL
THREAT SHOULD BECOME LESS AS STORMS RAPIDLY INCREASE IN COVERAGE.
THE DEVELOPING LINEAR MCS SHOULD HAVE A POTENTIAL FOR ISOLATED WIND
DAMAGE AND HAIL WITH THE MORE INTENSE LINE-SEGMENTS. FURTHER
SOUTHWEST ACROSS WCNTRL TX...THE MODELS SUGGEST LARGE-SCALE ASCENT
WILL BE QUITE WEAK. HOWEVER...FORECAST SOUNDINGS SUGGEST VERTICAL
SHEAR AND MODERATE INSTABILITY WILL BE SUFFICIENT FOR AN ISOLATED
STRONG CELLL IF CONVECTIVE CAN INITIATE.
...SRN ROCKIES/SRN HIGH PLAINS...
THE SRN END OF A HIGH-AMPLITUDE UPPER-LEVEL TROUGH WILL MOVE SEWD
ACROSS THE SRN ROCKIES MONDAY. AS SFC TEMPS HEAT UP BY
MIDDAY...SCATTERED DISCRETE THUNDERSTORMS SHOULD DEVELOP AHEAD OF
THE TROUGH AXIS ALONG A TONGUE OF WEAK INSTABILITY EXTENDING NWWD
ACROSS NE NM INTO FAR SRN CO. FORECAST SOUNDINGS ALONG THE
INSTABILITY AXIS MONDAY AFTERNOON SHOW STRONG VERTICAL SHEAR
PROFILES WITH COLD AIR ALOFT WITH 500 MB TEMPS AROUND -12 TO -15C.
IN SPITE OF THE WEAK INSTABILITY...THE VERTICAL SHEAR...STEEP LAPSE
AND STRONG LARGE-SCALE ASCENT MAY SUPPORT A FEW STRONG CELLS WITH
HAIL POTENTIAL.
..BROYLES.. 09/20/2009
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
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.
No comments:
Post a Comment