Post by SKYSUMMIT on Oct 16, 2007 20:30:46 GMT -6
SEL0
URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 710
NWS STORM PREDICTION CENTER NORMAN OK
1110 AM CDT WED OCT 17 2007
THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF
SOUTHWEST ARKANSAS
MUCH OF WESTERN AND NORTHERN LOUISIANA
PARTS OF EASTERN TEXAS
COASTAL WATERS
EFFECTIVE THIS WEDNESDAY MORNING AND EVENING FROM 1110 AM UNTIL
600 PM CDT.
TORNADOES...HAIL TO 1.5 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.
THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 85 STATUTE
MILES EAST AND WEST OF A LINE FROM 20 MILES NORTH OF TEXARKANA
ARKANSAS TO 65 MILES SOUTHWEST OF INTRACOASTAL CITY LOUISIANA.
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU0).
REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.
OTHER WATCH INFORMATION...CONTINUE...WW 708...WW 709...
DISCUSSION...VERY MOIST AIRMASS ALONG WITH FAVORABLE LOW LEVEL SHEAR
PROFILES WILL SUPPORT INCREASING TORNADIC SUPERCELL POTENTIAL
THROUGH THE AFTERNOON. STORMS WILL INCREASE NWD THRU WATCH AREA AS
AIR MASS CONTINUES TO DESTABILIZE.
AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
550. MEAN STORM MOTION VECTOR 23025.
...HALES
MESOSCALE DISCUSSION 2091
NWS STORM PREDICTION CENTER NORMAN OK
0936 AM CDT WED OCT 17 2007
AREAS AFFECTED...FAR SERN TX...LA...SRN AR
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 171436Z - 171630Z
STORMS SHOULD INCREASE IN INTENSITY AND COVERAGE THROUGH THE DAY AND
A TORNADO WATCH MAY BECOME NECESSARY.
SURFACE ANALYSIS SHOWS AN EXTREMELY MOIST AIR MASS ADVECTING NWD OUT
OF THE WRN GULF OF MEXICO WITH DEWPOINTS IN THE MID TO UPPER 70S F.
A WEAK MESO LOW WAS NOTED AS WELL AND COULD BE SEEN ON VISIBLE
IMAGERY OVER SERN TX. VAD WIND PROFILES ACROSS LA WERE INDICATING
MODERATE LOW LEVEL SHEAR WITH 0-1 SRH VALUES OF 150-250 M2/S2.
HOWEVER...SOME WEAKNESS IN THE WIND FIELDS/HODOGRAPHS WAS NOTED IN
THE 2-4 KM LAYER.
OVER THE NEXT SEVERAL HOURS...AXIS OF LOW LEVEL
CONVERGENCE...PERSISTENT WARM/MOIST ADVECTION AND SOME POCKETS OF
HEATING SHOULD ALLOW FOR A GRADUAL INCREASE IN STORMS ACROSS SE
TX/LA AND SPREADING NWD INTO SRN AR. TORNADO THREAT WILL NOT BE HIGH
INITIALLY...BUT WILL INCREASE AS UPPER TROUGH APPROACHES FROM THE W.
AS THIS OCCURS...WIND FIELDS AT ALL LEVELS WILL INCREASE AND BECOME
MORE FAVORABLE FOR SUSTAINED UPDRAFTS AND SUPERCELLS WITH THREAT OF
TORNADOES.
..JEWELL.. 10/17/2007
ATTN...WFO...JAN...LIX...LZK...LCH...SHV...
29529435 32789431 33549371 33999310 34009219 33669133
32699129 30759174 29809213 29649259 29759331 29719376
From the SPC:
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
From the HWO:
855 PM CDT TUE OCT 16 2007
THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF GULF OF
MEXICO...SOUTHEAST LOUISIANA AND SOUTHERN MISSISSIPPI.
.DAY ONE...TONIGHT
THUNDERSTORMS...
THERE IS A SLIGHT CHANCE OF THUNDERSTORMS AFTER MIDNIGHT AS AN UPPER
LEVEL DISTURBANCE APPROACHES THE AREA. THE BEST CHANCE WILL BE
SOUTH OF THE INTERSTATE 10 AND 12 CORRIDOR. SEVERE THUNDERSTORMS ARE
NOT EXPECTED...BUT THERE COULD BE AREAS RECEIVING BRIEF HEAVY RAIN
ALONG WITH OCCASIONAL CLOUD TO GROUND LIGHTNING AND GUSTY WINDS.
HIGH TIDES...
TIDES ARE RUNNING ABOUT ONE FOOT TO ONE AND ONE HALF FEET ABOVE
NORMAL DUE TO PERSISTENT EAST TO SOUTHEAST WINDS OVER THE LAST FEW
DAYS. ABNORMALLY HIGH LUNAR TIDES AND CONTINUED MODERATE SOUTHEAST
WINDS TONIGHT WILL CAUSE WATER LEVELS TO RISE THROUGH THE TIME OF
HIGH TIDE...WHICH OCCURS BETWEEN MIDNIGHT AND 5 AM ALONG THE COAST...
AND BETWEEN 5 AM AND 1 PM WEDNESDAY MORNING IN LAKE PONTCHARTRAIN.
THESE LEVELS WILL BE COMPARABLE TO OR SLIGHTLY HIGHER THAN THE HIGH
TIDE EVENTS FROM EARLIER THIS MONTH. AT THESE TIDE LEVELS...ONLY
MINOR FLOODING OF LOW LYING AREAS IS POSSIBLE OUTSIDE OF THE LEVEE
PROTECTION SYSTEM.
.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY
SCATTERED TO NUMEROUS THUNDERSTORMS ARE EXPECTED WEDNESDAY AS
VERY TROPICAL MOISTURE INTERACTS WITH AN UPPER LEVEL DISTURBANCE.
THE COMBINATION OF A MODERATELY UNSTABLE AIRMASS AND WIND SHEAR IN
THE ATMOSPHERE MAY CAUSE A FEW THUNDERSTORMS TO BECOME SEVERE WITH
THE MAIN THREAT BEING AN ISOLATED TORNADO AND STRONG...POSSIBLY
DAMAGING WINDS. IN ADDITION...LOCALLY HEAVY RAINFALL AMOUNTS OF 2
TO 3 INCHES IN A SHORT PERIOD OF TIME ARE POSSIBLE...WHICH MAY LEAD
TO HEAVY PONDING OF WATER ON SOME ROADS AND LOW LYING AREAS .
SCATTERED THUNDERSTORMS ARE POSSIBLE AHEAD OF A COLD FRONT ON
THURSDAY...AND AGAIN AHEAD OF A STRONGER COLD FRONT SUNDAY NIGHT INTO
MONDAY. ISOLATED STRONG TO SEVERE THUNDERSTORMS ARE POSSIBLE SUNDAY
NIGHT INTO MONDAY.
.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION IS NOT ANTICIPATED THROUGH WEDNESDAY.