SWODY1
SPC AC 171621
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1121 AM CDT WED OCT 17 2007
VALID 171630Z - 181200Z
..THERE IS A MDT RISK OF SVR TSTMS ACROSS PORTIONS OF CNTRL/ERN
OK...SERN KS...SWRN/SCNTRL MO...MOST OF AR AND EXTREME NERN TX...
..THERE IS A SLGT RISK OF SVR TSTMS ACROSS A LARGE PART OF THE
CNTRL/SRN PLAINS EWD INTO THE LWR/MID MS VLYS...
..POTENTIALLY SIGNIFICANT SEVERE WEATHER EPISODE POSSIBLE THROUGH
TONIGHT...WITH A THREAT FOR A FEW STRONG AND/OR...LONG-TRACK
TORNADOES...
..SRN/CNTRL PLAINS INTO THE LWR/MID MS VLYS THROUGH TONIGHT...
WATER VAPOR IMAGERY PORTRAYS AN ENERGETIC MID-UPR FLOW REGIME TODAY
THAT WILL EVENTUALLY LEAD TO A DEEP CLOSED LOW OVER THE CNTRL PLAINS
BY THE END OF THE PD. BEFORE THEN...A STRONG MID-LEVEL
IMPULSE...NOW CROSSING THE TX PNHDL/S PLAINS...WILL EJECT NEWD AS A
POWERFUL PAC JET STREAK TRANSLATES ESEWD ACROSS THE GRT BASIN REGION
TODAY. A LOWER AMPLITUDE IMPULSE WILL MOVE NWD FROM THE UPR TX
COAST AND INTO THE MID-SOUTH THROUGH TONIGHT.
AT THE SFC...THE LEE LOW OVER WCNTRL KS WILL DEEPEN AS IT TRACKS
NEWD...REACHING NERN NEB OR NWRN IA BY 12Z THURSDAY. TO THE S OF
THIS LOW...A DRY LINE WILL MIX EWD ACROSS WRN OK AND CNTRL TX BY
MID-AFTN...THEN INTO THE OZARKS TONIGHT. THE PRIMARY WARM FRONT
WILL LIFT NWD INTO THE CORN BELT AND MIDWEST BY TONIGHT...WHILE A
SECONDARY WARM FRONT DEVELOPS FROM NERN TX/SERN OK AND LWR MS VLY
REGIONS EARLY THIS AFTN INTO THE MID-SOUTH BY TONIGHT.
THE BEGINNING OF AN ACTIVE 24-48 HR SVR WEATHER EPISODE CONTINUES TO
UNFOLD AT MID-DAY WITH MULTIPLE SVR THREAT AREAS EXPECTED TO EVOLVE
BY LATE AFTN/EVE. FIRST AREA OF CONCERN WILL BE THE
CONTINUATION/EXPANSION OF STG-SVR TSTMS ONGOING FROM CNTRL-NRN OK
AND SCNTRL KS NEWD INTO THE MID-MS VLY THIS AFTN/TONIGHT. THIS
ACTIVITY APPEARS LARGELY TIED TO THE LEAD UPR WAVE CURRENTLY
EJECTING NEWD ACROSS THE CNTRL PLAINS. ADDITIONAL LARGE SCALE
ASCENT FROM THE APPROACHING MID-LVL JET MAX AND DESTABILIZING/
MOISTENING BOUNDARY LAYER DOWNSTREAM INTO THE OZARKS/MID-MS VLY WILL
CONTRIBUTE TO MAINTAINING A SVR THREAT THROUGH TONIGHT. DEEP LAYER
WIND FIELDS ARE EXPECTED TO STRENGTHEN WITH THE APPROACH OF THE
70-90 KT H5 JET. RECENT BOWING STRUCTURES/LINEAR NATURE TO THE
STORMS COULD EVOLVE AND/OR DEVELOP INTO MORE DISCRETE SUPERCELL
STRUCTURES LATER THIS AFTN...PARTICULARLY ACROSS NERN OK INTO
EXTREME SERN KS AND SWRN/SCNTRL MO...WITH AN ADDED RISK FOR A FEW
STRONG TORNADOES.
MEANWHILE...TSTMS MAY REDEVELOP WEST/SOUTH OF THE ONGOING ACTIVITY
ACROSS PARTS OF CNTRL KS SWD INTO NWRN TX. LATEST MODEL
GUIDANCE...INCLUDING NAM12/WRF-NMM4...SUGGEST THAT SUFFICIENT
HEATING AND CONVERGENCE WILL MATERIALIZE FOR AT LEAST ISOLD TSTM
DEVELOPMENT ALONG THE DRYLINE. MOST UNSTABLE PROFILES SHOULD
DEVELOP ALONG SRN EDGE OF MORNING ACTIVITY...NAMELY ACROSS CNTRL OK
SWD INTO N TX...THEN GROW UPSCALE INTO STG-SVR STORMS ACROSS ERN
OK/NERN TX THIS EVE. FCST WIND FIELDS WILL BE MORE THAN SUFFICIENT
FOR SUPERCELLS WITH LARGE HAIL AND DMGG WIND GUSTS. THREAT FOR A
FEW STRONG TORNADOES WILL LIKELY EXIST...ESPECIALLY WHERE LOW-LEVEL
FLOW CAN MAINTAIN A BACKED/SELY COMPONENT. ATTM...THIS APPEARS MORE
LIKELY TO OCCUR OVER CNTRL/ERN OK AS THE STORMS BEGIN TO ENCOUNTER
MORE SUBSTANTIAL LOW-LEVEL MOISTURE ADVECTING NWWD FROM THE UPR TX
COAST.
LASTLY...ANOTHER ZONE OF ENHANCED SVR THREATS WILL EXIST FROM THE
UPR TX COASTAL REGION NWD INTO LA AND AR ASSOCD WITH A PLUME OF RICH
TROPICAL MOISTURE SURGING NWD WITH A GULF IMPULSE. MODEST LOW-LEVEL
WIND/SHEAR PROFILES ALREADY IN PLACE WILL CONTINUE TO IMPROVE WITH
TIME AS THE SRN PLAINS UPR JET PUNCHES EWD AND LOW-LEVEL SLY FLOW
RESPONDS. HIGHEST POTENTIAL FOR EMBEDDED SUPERCELLS WITH
TORNADOES...SOME STRONG...WILL SPREAD NEWD FROM THE UPR TX COAST/WRN
LA AT MID-DAY AND REACH THE MID-SOUTH/OZARKS BY TONIGHT.
.RACY.. 10/17/2007
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