SWODY1
SPC AC 251228
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0728 AM CDT SUN OCT 25 2009
VALID 251300Z - 261200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF SRN OK INTO CNTRL
TX THIS AFTERNOON AND TONIGHT...
...SYNOPSIS...
THE PRIMARY FEATURE OF INTEREST THIS PERIOD IS SHORT WAVE TROUGH AND
ASSOCIATED 100-120 KT UPPER-LEVEL JET STREAK OBSERVED OVER THE
PACIFIC NW/NRN INTERMOUNTAIN REGION INTO GREAT BASIN BASED ON 25/00Z
UPPER-AIR ANALYSIS. THIS UPPER SYSTEM IS FORECAST TO DIG SEWD
THROUGH THE CNTRL/SRN ROCKIES AND EVENTUALLY INTO THE ADJACENT HIGH
PLAINS...EFFECTIVELY SHARPENING LARGER-SCALE TROUGH OVER THE CNTRL
CONUS.
AT THE SURFACE...RIDGING ACROSS THE NRN/CNTRL HIGH PLAINS WILL
SUPPORT THE SWD PROGRESSION OF COLD FRONT THROUGH THE SRN HIGH
PLAINS WITH THIS BOUNDARY LIKELY EXTENDING FROM WEAK SURFACE LOW
OVER WI SWWD THROUGH CNTRL OK INTO NWRN/W-CNTRL TX BY EARLY EVENING.
THIS BOUNDARY IS EXPECTED TO BE THE PRIMARY FOCUS FOR STRONG TO
POTENTIALLY SEVERE STORM DEVELOPMENT LATER TODAY INTO TONIGHT.
...OK/TX...
EARLY MORNING GOES SOUNDER AND GPS PW DATA INDICATE MOISTURE
INCREASING FROM THE TX COAST NWD/NEWD THROUGH THE OZARK PLATEAU
ALONG 40-50 KT SWLY LLJ AXIS. THOUGH LLJ MAY UNDERGO SOME DIURNAL
WEAKENING...SUSTAINED LOW-LEVEL SLY WIND COMPONENT WILL SUPPORT THE
CONTINUED MOISTENING OF WARM SECTOR WITH DEWPOINTS INCREASING TO
AROUND 60 F NEAR THE RED RIVER...AND MID/UPPER 60S AS FAR N AS THE
HILL COUNTRY. THIS PROCESS WILL OCCUR BENEATH EML PLUME /OBSERVED
BY 12Z SRN HIGH PLAINS SOUNDINGS/ WHICH WILL BE ADVECTED EWD IN
ADVANCE OF AMPLIFYING MIDLEVEL TROUGH. THESE DIFFERENTIAL
ADVECTIONS WILL CONTRIBUTE TO AIR MASS DESTABILIZATION TODAY WITH
MLCAPE RANGING FROM LESS THAN 500 J/KG OVER CNTRL OK TO 1000-2000
J/KG OVER CNTRL TX.
CAP ASSOCIATED WITH EML WILL LIKELY INHIBIT SURFACE-BASED STORM
INITIATION UNTIL LATE THIS AFTERNOON OR EVENING. INITIAL STORM
DEVELOPMENT IS EXPECTED NEAR OR N OF THE RED RIVER AS STRENGTHENING
COLD FRONTAL CIRCULATION AND INCREASED HEIGHT FALLS ERODE CAP ACROSS
NRN EXTENSION OF INSTABILITY AXIS. THESE FORCING MECHANISMS SHOULD
SUPPORT BACK-BUILDING STORM DEVELOPMENT ALONG FRONT INTO CNTRL TX
TONIGHT.
FORECAST HODOGRAPHS INDICATE PRONOUNCED VEERING OF WINDS WITH HEIGHT
THROUGH THE LOWEST 3-4 KM AGL WITH DEEP-LAYER BULK SHEAR INCREASING
TO 40-50 KT. AS SUCH...INITIAL CONVECTIVE MODE MAY BE
SUPERCELLULAR. HOWEVER...INCREASING ANAFRONTAL AIRFLOW STRUCTURE
ASSOCIATED WITH COLD FRONT SHOULD RESULT IN A FAIRLY RAPID
TRANSITION TO A LINEAR SYSTEM WITH HAIL AND DAMAGING WIND GUSTS
BEING THE PRIMARY SEVERE THREATS.
..MEAD/GRAMS.. 10/25/2009
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
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