Severe Thunderstorm Warning 246, NWS Amarillo, TX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AMARILLO TX
1158 PM CDT WED AUG 12 2009

.UPDATE...
MAIN REASON FOR UPDATE WAS TO ADJUST POPS AND TO CLEAN UP EVENING
WORDING IN THE ZPF. CURRENT WATER VAPOR IMAGERY INDICATES SHORTWAVE
TROUGH IN NE CO. THIS HAS TRIGGERED AN AREA OF THUNDERSTORMS WHICH CONTINUE
TO ACCELERATE SWD ACROSS THE TX/OK PANHANDLES. WENT AND ADJUSTED POPS
UPWARD WITH THE HIGHEST POPS ACROSS THE CENTRAL AND ERN SECTIONS OF
THE AMA CWA. ALTHOUGH NO OTHER SHOWERS AND THUNDERSTORMS HAVE
DEVELOPED UPSTREAM...STILL MAINTAINED SLIGHT CHANCE POPS ACROSS THE
REMAINDER OF THE PANHANDLES AS THE AFOREMENTIONED SHORT WAVE TROUGH
IS FORECAST TO DROP THROUGH THE PANHANDLES OVERNIGHT.

CLK

&&

.AVIATION...
FOR THE 06Z TAFS...MAIN FORECAST CONCERN IS ON CONVECTION CHANCES IN
THE VERY SHORT TERM. THUNDERSTORM COMPLEX IS TRACKING SWD ACROSS THE
PANHANDLES. GIVEN CURRENT TRACK...TIMED STORMS TO AFFECT THE KAMA
TERMINAL BETWEEN 06-08Z. STILL POSSIBLE FOR ADDITIONAL STORMS TO POP
UP OVERNIGHT AS A SHORTWAVE TROUGH PROPAGATES INTO THE
PANHANDLES...HOWEVER CONFIDENCE IS LOW ENOUGH TO PRECLUDE ANY MENTION
AT KDHT/KGUY. UPPER RIDGE EDGES OVER TX THURSDAY...BUT WITH NW FLOW
ALOFT...CAN EXPECT ANOTHER REPEAT PERFORMANCE ON MOUNTAIN CONVECTION
MAKING ITS WAY INTO THE AREA. FOR NOW JUST INSERTED CB REMARKS AFTER
00Z AS EXPECT DRY CONDITIONS DURING THE DAY. WINDS WILL GENERALLY
REMAIN OUT OF THE SOUTH WITH SPEEDS AROUND 12-15 KTS.

CLK

&&

.PREV DISCUSSION... /ISSUED 910 PM CDT WED AUG 12 2009/

UPDATE...
COMPLEX OF STRONG THUNDERSTORMS MOVING ACROSS SE CO/SW KS IN
ASSOCIATION TO A SHORTWAVE TROUGH DROPPING SEWD ALONG THE NORTHERN
PERIPHERY OF THE UPPER RIDGE CENTERED OVER THE FOUR CORNERS REGION.
THE 00Z SOUNDING AT DDC INDICATES AN INVERTED TYPE V
PROFILE...INDICATING STRONG WINDS WOULD BE THE MAIN THREAT FROM ANY
STORMS THAT MIGRATE INTO THE NRN SECTIONS OF AMA CWA. GIVEN STORM
MOVEMENT TO THE SOUTHEAST...WENT AND BUMPED UP POPS ACROSS THE OK
PANHANDLE THIS EVENING. ALTHOUGH CURRENT RADAR IMAGERY DOES NOT SHOW
MUCH ELSE IN THE WAY OF CONVECTION IN NE NM...HELD ONTO POPS
OVERNIGHT AS ANY OUTFLOW BOUNDARY MAY TRIGGER ADDITIONAL STORMS
WHILE A LLVL JET INTENSIFIES ACROSS THE AREA. REMAINDER OF FORECAST
LOOKS ON TRACK WITH ONLY MINOR ADJUSTMENTS MADE TO TEMP/WIND/DEWPOINT/QPF
GRIDS.

CLK

PREV DISCUSSION... /ISSUED 557 PM CDT WED AUG 12 2009/

AVIATION...
A NORTHWEST FLOW ALOFT WILL BRING THUNDERSTORMS FROM EASTERN COLORADO
AND EASTERN NEW MEXICO INTO THE PANHANDLES TONIGHT. ALL THREE TAF
SITES HAVE A SHOT AT A TSRA WITH DHT HAVING THE BEST CHANCE. SKIES
WILL CLEAR AGAIN THURSDAY MORNING. THEN TSRA MAY GET CLOSE TO THE DHT
TAF SITE JUST BEFORE THE END OF THIS FORECAST. SOUTHEAST AND SOUTH
WINDS WILL PREVAIL. VFR CONDITIONS WILL PREVAIL OUTSIDE OF THUNDERSTORMS.

PREV DISCUSSION... /ISSUED 246 PM CDT WED AUG 12 2009/

DISCUSSION...
UPPER LEVEL PATTERN CONTINUES WITH A RIDGE ACROSS THE SOUTHWEST
DESERTS AND A TROUGH IN THE NORTHWEST AND ACROSS THE APPALACHIANS IN
THE EAST. THROUGH THE NEXT SEVEN DAYS THE NORTHWEST TROUGH WILL DIG
INTO THE WESTERN UNITED STATES AND SUPPRESS THE FOUR CORNERS RIDGE.
RIDGE REDEVELOPS OVER THE SOUTHEASTERN UNITED STATES. THE WESTERN
TROUGH WILL BE THE PREDOMINANT WEATHER PLAYER FOR THE PANHANDLES IN
THE EXTENDED FORECAST.

THUNDERSTORMS ALREADY DEVELOPING ALONG THE HIGHER TERRAIN OF NEW
MEXICO AND COLORADO THIS AFTERNOON. SHORTWAVE TROUGH OVER THE FOUR
CORNERS IS EXPECTED TO INCREASE THIS ACTIVITY THROUGH THE EVENING AND
OVERNIGHT TONIGHT. THUNDERSTORMS WILL LIKELY DRIFT DOWN INTO THE
PANHANDLES LATE IN THE EVENING AND SPREAD ACROSS THE AREA OVERNIGHT.
CANNOT RULE OUT ISOLATED THUNDERSTORMS DEVELOPING IN THE PANHANDLES THIS
AFTERNOON...BUT THE MAIN SHOW WILL BE TONIGHT. POPS HAVE BEEN
INCREASED DURING THE OVERNIGHT HOURS...FITTING WELL WITH RECENT TRENDS
OF NIGHTTIME CONVECTION.

RIDGE BEGINS TO WEAKEN AND MOVE ACROSS THE PANHANDLES ON THURSDAY.
SLIGHTLY WARMER TEMPERATURES ARE EXPECTED ESPECIALLY IN THE SOUTHERN
TEXAS PANHANDLE. AS FLOW BECOMES WESTERLY...CANNOT RULE OUT STORMS
DEVELOPING OVER THE MOUNTAINS AND DRIFTING INTO THE WESTERN PANHANDLES
OR DEVELOPING WITHIN THE LEE TROUGH ITSELF IN THE EVENING.

SHORTWAVE TROUGH TRAVERSES THE SOUTHERN ROCKIES AND PASSES OVER THE
PANHANDLES ON FRIDAY WITHIN THE SOUTHWESTERLY FLOW ALOFT...INCREASING
THE CHANCES FOR THUNDERSTORMS. INCREASED POPS INTO THE 30 TO 40
PERCENT RANGE...WHICH AGREES WELL WITH THE MAV AND MET GUIDANCE FOR
FRIDAY NIGHT.

NEXT BIG FEATURE IS A COLD FRONT WHICH MOVES INTO THE PANHANDLES
SATURDAY NIGHT AND SUNDAY AS THE WESTERN TROUGH MOVES INTO THE
NORTHERN PLAINS. THIS WILL SERVE AS A FOCUS FOR THUNDERSTORM
DEVELOPMENT ON SUNDAY...AND THUS 30 TO 40 POPS HAVE BEEN ADDED HERE
AS WELL. HIGH TEMPERATURES WILL BE COOLER ON SUNDAY AS
WELL...ESPECIALLY IN THE NORTH. FRONT LINGERS IN THE REGION THROUGH
MONDAY...SO POPS HAVE BEEN CONTINUED THROUGH MONDAY NIGHT. ANOTHER
COLD FRONT MAY MOVE INTO THE AREA WEDNESDAY.

GENERALLY UNDERCUT THE MAV GUIDANCE FOR MAX AND MIN TEMPERATURES IN
THE FIRST FEW PERIODS...FOLLOWING RECENT TRENDS. GENERALLY STAYED
WITH THE 00Z MEX GUIDANCE IN THE EXTENDED FORECAST.

KIMBLE

FIRE WEATHER...
FIRE WEATHER CONCERNS ARE LOW DUE TO RECENT HEAVY PRECIPITATION AND
THE CONTINUED CHANCES FOR PRECIPITATION. RELATIVE HUMIDITIES WILL
REMAIN HIGH WITH WINDS GENERALLY LESS THAN 20 KT.

KIMBLE

&&

.AMA WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
OK...NONE.

&&

15/05

TEXAS/OKLAHOMA PANHANDLES HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE AMARILLO TX
908 PM CDT WED AUG 12 2009

OKZ001>003-TXZ001>020-131100-
ARMSTRONG-BEAVER-CARSON-CIMARRON-COLLINGSWORTH-DALLAM-DEAF SMITH-
DONLEY-GRAY-HANSFORD-HARTLEY-HEMPHILL-HUTCHINSON-LIPSCOMB-MOORE-
OCHILTREE-OLDHAM-POTTER-RANDALL-ROBERTS-SHERMAN-TEXAS-WHEELER-
908 PM CDT WED AUG 12 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE TEXAS AND OKLAHOMA
PANHANDLES.

.DAY ONE...

THUNDERSTORMS ARE POSSIBLE ACROSS THE TEXAS AND OKLAHOMA PANHANDLES
THROUGH TONIGHT. HEAVY RAIN WILL BE THE PRIMARY CONCERN WITH PONDING
OF FLOOD PRONE AREAS POSSIBLE. IN ADDITION...SOME STORMS COULD
APPROACH SEVERE STRENGTH...WHICH MAY RESULT IN DAMAGING WINDS AND
MARGINALLY SEVERE HAIL.

.DAYS TWO THROUGH SEVEN...

GENERALLY AFTERNOON AND EVENING THUNDERSTORMS WILL BE POSSIBLE ACROSS
MUCH OF THE REGION THROUGH MONDAY NIGHT. HEAVY RAIN WILL BE THE
PRIMARY THREAT FROM ANY STORMS THAT DEVELOP...WHICH MAY LEAD TO
LOCALIZED FLOODING.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED THROUGH TONIGHT.

GOEHRING

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE AMARILLO TX
242 AM CDT THU AUG 13 2009

..TIME..    ...EVENT...     ...CITY LOCATION...      ...LAT.LON...
..DATE..    ....MAG....     ..COUNTY LOCATION.. ST.. ...SOURCE....
            ..REMARKS..

0130 AM     TSTM WND GST     PAMPA                   35.55N 100.96W
08/13/2009  E60 MPH          GRAY               TX   LAW ENFORCEMENT

            DISPATCH REPORTED VERY STRONG WINDS WHEN THE STORM CAME
            THROUGH.

&&

EVENT NUMBER AMA0900164

SFJ

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE AMARILLO TX
243 AM CDT THU AUG 13 2009

..TIME..    ...EVENT...     ...CITY LOCATION...      ...LAT.LON...
..DATE..    ....MAG....     ..COUNTY LOCATION.. ST.. ...SOURCE....
            ..REMARKS..

0130 AM     TSTM WND GST     2 E PAMPA               35.55N 100.93W
08/13/2009  M61 MPH          GRAY               TX   MESONET

&&

EVENT NUMBER AMA0900165

SFJ

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE AMARILLO TX
251 AM CDT THU AUG 13 2009

TXZ015-019-020-130815-
WHEELER TX-COLLINGSWORTH TX-DONLEY TX-
251 AM CDT THU AUG 13 2009

...SIGNIFICANT WEATHER ADVISORY...

THE NATIONAL WEATHER SERVICE IN AMARILLO HAS ISSUED A SIGNIFICANT
WEATHER ADVISORY EFFECTIVE UNTIL 315 AM CDT FOR DONLEY...
COLLINGSWORTH AND WHEELER COUNTIES.

AT 247 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
LINE OF STRONG THUNDERSTORMS FROM SHAMROCK TO 9 MILES WEST OF
GREENBELT LAKE...MOVING SOUTH AT 25 MPH.

UP TO ONE HALF INCH SIZE HAIL AND WINDS AROUND 50 MPH ARE POSSIBLE.

PERSONS IN THE PATH OF THESE STORMS SHOULD CLOSELY MONITOR WEATHER
RADIO OR OTHER MEDIA FOR OTHER UPDATES AND POSSIBLE WARNINGS. BE
PREPARED TO TAKE ACTION IF A WARNING IS ISSUED.

SJOHNSON