Alert archive / Texas / Severe Thunderstorm Warnings in 2009

Severe Thunderstorm Warning 272, NWS Amarillo, TX

August 17, 2009Dallam County, Sherman County, Texas

NWS Amarillo, TX issued this severe thunderstorm warning at Aug 17, 2009, 11:05 PM CDT for Dallam County, Sherman County, Texas. It was in force for 55 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Aug 17, 2009, 11:05 PM CDT (04:05 UTC)
Expired: Aug 18, 2009, 12:00 AM CDT
In force: 55 min
Issued by: NWS Amarillo, TX
Area: Storm-based polygon

Counties Dallam County, TX, Sherman County, TX

The radar

The Amarillo radar (KAMA), 126 km from the middle of the area, began a volume at 04:06 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Aug 17, 3:18 PM CDT	Severe Thunderstorm Watch	SPC	10 hr

The nearest sounding before it

Amarillo Airport, TX (KAMA), launched 00:00Z, 4.1 hours before the alert went out and 127 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 607 J/kg
Mixed-layer CIN: -208 J/kg
Mixed-layer LCL: 2171 m above ground
0-6 km bulk shear: 55 kt
0-1 km storm-relative helicity: 134 m²/s²
0-3 km storm-relative helicity: 432 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.6

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Amarillo, TX wrote its last area forecast discussion before this severe thunderstorm warning went out at Aug 17, 6:31 PM CDT, 4 hours 34 minutes earlier.

Area forecast discussion, Aug 17, 6:31 PM CDT, 4 hours 34 minutes before

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE AMARILLO TX
631 PM CDT MON AUG 17 2009

.AVIATION...
CONVECTION CHANCES REMAIN THE PRIMARY AVIATION CONCERN. FRONTAL
BOUNDARY AND NUMEROUS OUTFLOW BOUNDARIES ARE PRESENT ACROSS THE
REGION WITH SEVERAL THUNDERSTORM CLUSTERS/COMPLEXES. EARLY HOURS OF
THE TAFS ARE BLANKETED WITH CB/VCTS REMARKS...WITH TEMPO GROUPS AS
MORE THUNDERSTORMS MOVE OUT OF SE COLORADO AND NE NEW MEXICO.
MVFR/IFR CIGS AND VSBYS WILL BE POSSIBLE WITH ANY THUNDERSTORM THAT
DIRECTLY IMPACTS THE TERMINALS...AND AMENDMENTS MAY BECOME NECESSARY.
LOW CLOUDS/FOG MAY BECOME AN ISSUE TUES MORNING AT DHT/GUY...BUT WILL
CONTINUE TO ASSESS THAT POSSIBILITY.

TAB

&&

.PREV DISCUSSION... /ISSUED 340 PM CDT MON AUG 17 2009/

DISCUSSION...
PRIMARY FORECAST ISSUES CENTER AROUND CONVECTIVE CHANCES DURING THE
SHORT TERM.

ACTIVE WEATHER APPEARS TO BE IN STORE FOR THE PANHANDLES DURING THE
NEXT 24 TO 48 HOURS. MAIN FOCUS FOR SHOWER AND THUNDERSTORM
DEVELOPMENT OVER THE NEXT COUPLE OF DAYS WILL BE FRONTAL BOUNDARY
WHICH WILL REMAIN THE AREA. IN ADDITION...UPPER LEVEL SHORTWAVE
ENERGY AND REMNANT OUTFLOW BOUNDARIES WILL ALSO PROVIDE A SOURCE OF
LIFT TO FURTHER SUPPORT CONVECTION DURING THIS TIME FRAME. AS OF
DISCUSSION TIME...FRONTAL BOUNDARY IS STRETCHED ACROSS THE
PANHANDLES ALONG A LINE FROM ALLISON TO VEGA. CONVECTION HAS ONCE
AGAIN FIRED ALONG THIS OUTFLOW/FRONTAL BOUNDARY...AND IN SE COLORADO
AND SW KANSAS IN POST FRONTAL UPSLOPE ENVIRONMENT.

COVERAGE OF SHOWERS/TSTORMS SHOULD BEGIN TO INCREASE OF THE NEXT
SEVERAL HOURS AS ATMOSPHERE CONTINUES TO DESTABILIZE. ALSO...AN
UPPER LEVEL DISTURBANCE IN WESTERLY FLOW WILL TRACK ACROSS THE
REGION. POPS WERE RETAINED THIS EVENING AT ALL LOCATIONS...BUT
INCREASED INTO THE LIKELY CATEGORY ACROSS THE NORTHERN AND
NORTHEASTERN ZONES IN CLOSER PROXIMITY TO THE BOUNDARY AND BETTER
SOURCE OF MOISTURE. SHORT TERM MODEL PROGS PAINT PWATS IN EXCESS OF
1.50 INCHES ACROSS THE ACROSS THE THESE AREAS. WITH ANY STORMS THAT
DO DEVELOP...LOCALLY HEAVY RAINFALL WOULD BECOME A THREAT.
HOWEVER...WITH UNCERTAINTY ON WHERE ANY MCS OR THUNDERSTORM
COMPLEX(ES) MAY END UP TRACKING...HAVE DECIDED TO HOLD OFF HOISTING
A FLASH FLOOD WATCH...BUT WILL CONTINUE TO MENTION THE HWO. LATER
SHIFTS MAY NEED TO CONSIDER A FLASH FLOOD WATCH FOR TOMORROW FOR
PORTIONS OF THE PANHANDLES DEPENDING ON HOW CONVECTION/HEAVY RAIN
PANS OUT THIS EVENING. STRONG TO SEVERE STORMS WILL BE POSSIBLE WITH
PLENTY OF INSTABILITY ACROSS THE AREA AND ANY THUNDERSTORM COMPLEX
THAT HAPPENS TO DEVELOP. SAME SCENARIO SEEMS LIKELY ON TUESDAY WITH
THE FRONT STILL MEANDERING ABOUT THE PANHANDLES AND MORE SHORTWAVE
ENERGY SWINGING ACROSS THE AREA...CHANCE POPS WERE RETAINED ON
TUESDAY AND TUESDAY NIGHT. AS FAR AS TEMPERATURES ARE
CONCERNED...MAIN THEME OF THE SHORT TERM WAS TO UNDERCUT MAV
GUIDANCE BY SEVERAL DEGREES WITH CONTINUED CHANCES OF SHOWERS/TSRA.
SOME LOCATIONS ACROSS THE NORTHERN ZONES MAY STRUGGLE TO REACH THE
MID 80S ON TUESDAY...WITH LOWER 90S ACROSS THE SOUTHEASTERN ZONES.

SLIGHT END POPS WERE RETAINED ON WEDNESDAY AND THURSDAY FOR NOW AS
THE NEXT FRONT BEGINS TO IMPACT THE PANHANDLES. NO POPS WERE
INTRODUCED IN THE FORECAST PAST THURSDAY. MEDIUM TO LONG TERM RUNS
OF THE GFS/EUROPEAN IN PRETTY GOOD AGREEMENT IN BUILDING THE UPPER
LEVEL RIDGE ACROSS THE SOUTHERN HIGH PLAINS. TEMPERATURES WILL BE
BEGIN TO MODERATE TOWARDS THE LATTER PART OF THE WEEK. LATEST GRIDS
REFLECT THIS WITH TEMPS MODERATING BACK INTO THE LOWER 90S BY THE
WEEK/S END. TRENDED TEMPS CLOSER TO THE 12Z MEX NUMBER FOR NOW...BUT
IF THE AREA CONTINUES TO RECEIVE SIGNIFICANT RAINS...TEMPS MAY NEED
TO BE LOWERED A TAD IN LATER FORECASTS.

TAB

FIRE WEATHER...
NO FIRE WEATHER CONCERNS UNTIL FURTHER NOTICE DUE CONTINUED CHANCES FOR
WETTING RAINS.

TAB

&&

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

&&

10/03

Hazardous weather outlook, Aug 17, 10:04 PM CDT, 1 hour 1 minute before

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In the hours before

Local storm report, Aug 17, 9:53 PM CDT, 1 hour 12 minutes before

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Local storm report, Aug 17, 9:57 PM CDT, 1 hour 8 minutes before

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Local storm report, Aug 17, 9:58 PM CDT, 1 hour 7 minutes before

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Special weather statement, Aug 17, 10:21 PM CDT, 44 minutes before

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Special weather statement, Aug 17, 10:25 PM CDT, 40 minutes before

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Special weather statement, Aug 17, 10:38 PM CDT, 27 minutes before

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The office that day

Everything else NWS Amarillo, TX issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 17, 7:08 PM CDT	Severe Thunderstorm Warning	AMA	Donley	67 min
Aug 17, 7:11 PM CDT	Severe Thunderstorm Warning	AMA	Gray, Wheeler	64 min
Aug 17, 7:36 PM CDT	Severe Thunderstorm Warning	AMA	Dallam	54 min
Aug 17, 8:22 PM CDT	Severe Thunderstorm Warning	AMA	Dallam, Sherman	53 min
Aug 17, 8:39 PM CDT	Severe Thunderstorm Warning	AMA	Collingsworth	44 min
Aug 17, 8:50 PM CDT	Severe Thunderstorm Warning	AMA	Hansford, Sherman	55 min
Aug 17, 9:19 PM CDT	Severe Thunderstorm Warning	AMA	Dallam	56 min
Aug 17, 9:25 PM CDT	Severe Thunderstorm Warning	AMA	Hansford, Hutchinson	65 min
Aug 18, 2:38 AM CDT	Areal Flood Advisory	AMA	Potter, Randall	112 min
Aug 18, 4:50 AM CDT	Flash Flood Watch	AMA	Armstrong, Carson, Collingsworth, Donley, Gray, Hansford and 10 more	23 hr
Aug 18, 5:48 PM CDT	Severe Thunderstorm Warning	AMA	Dallam, Hartley	57 min
Aug 18, 6:08 PM CDT	Severe Thunderstorm Warning	AMA	Deaf Smith, Oldham	82 min
Aug 18, 6:35 PM CDT	Tornado Warning	AMA	Deaf Smith, Oldham	40 min
Aug 18, 6:56 PM CDT	Severe Thunderstorm Warning	AMA	Dallam, Hartley	64 min
Aug 17, 7:43 PM CDT	Severe Thunderstorm Warning	AMA	Beaver, Texas	30 min

Nearby

Severe Thunderstorm Warnings in Texas, 2009 Every severe thunderstorm warning in 2009

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.