Alert archive / Texas / Mesoscale Discussions in 2003

Mesoscale Discussion 490

April 18, 200314 counties in Oklahoma; 25 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 18, 2003, 8:31 PM CDT for 14 counties in Oklahoma; 25 counties in Texas. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Apr 18, 2003, 8:31 PM CDT (01:31 UTC)
Expired
Apr 18, 2003, 11:00 PM CDT
In force
2 hr
Issued by
the Storm Prediction Center
All 39 counties

Caddo County, OK, Cleveland County, OK, Comanche County, OK, Cotton County, OK, Grady County, OK, Greer County, OK, Harmon County, OK, Jackson County, OK, Jefferson County, OK, Kiowa County, OK, McClain County, OK, Stephens County, OK, Tillman County, OK, Washita County, OK, Archer County, TX, Baylor County, TX, Borden County, TX, Childress County, TX, Clay County, TX, Cottle County, TX, Dickens County, TX, Fisher County, TX, Foard County, TX, Garza County, TX, Hardeman County, TX, Haskell County, TX, Howard County, TX, Jones County, TX, Kent County, TX, King County, TX, Knox County, TX, Martin County, TX, Mitchell County, TX, Nolan County, TX, Scurry County, TX, Stonewall County, TX, Throckmorton County, TX, Wichita County, TX, Wilbarger County, TX

The radar

The Altus AFB radar (KFDR), 96 km from the middle of the area, began a volume at 01:34 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

The nearest sounding before it

Amarillo Airport, TX (KAMA), launched 00:00Z, 1.5 hours before the alert went out and 243 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-pSkew-T log-p diagram, Amarillo Airport, TX at 00:00Z on 2003-04-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Amarillo Airport, TX at 00:00Z on 2003-04-19The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -14 square meters per square second.1939587897117136Sfc1 km3 km6 km9 kmRMLM
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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
3956 m above ground
0-6 km bulk shear
45 kt
0-1 km storm-relative helicity
-14 m²/s²
0-3 km storm-relative helicity
211 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

120 
ACUS11 KWNS 190131
SWOMCD
SPC MCD 190131 
OKZ000-TXZ000-190400-

MESOSCALE DISCUSSION 0490
NWS STORM PREDICTION CENTER NORMAN OK
0831 PM CDT FRI APR 18 2003

AREAS AFFECTED...PARTS OF W TX...NWRN TX AND SWRN/CNTRL OK

CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

VALID 190131Z - 190400Z

...TSTMS WILL INCREASE IN THE NEXT 2-4 HOURS WITH THE POTENTIAL
FOR MAINLY LARGE HAIL...

NOCTURNAL TSTM EVENT SHOULD BEGIN UNFOLDING ACROSS THE AREA AFTER
ABOUT 02-03Z AND A WW WILL LIKELY BE ISSUED SOON.

LONE SUPERCELL THAT WAS A LEFT MEMBER OF A SPLIT...HAS REMAINED
THE DOMINANT TSTM AND HAS BEEN PRODUCING HAIL TO THE SIZE OF
GOLFBALLS INVOF SPS.  THIS STORM IS MOVING 210/40 KTS AND WILL
PASS INTO SWRN OK AND COULD APPROACH DUNCAN BY 0215 UTC.

OTHERWISE...UPSTREAM...HIGH BASED CONVECTION HAS DEVELOPED
RAPIDLY OVER THE W TX MOUNTAINS INVOF WINK AND LIKELY MARKS THE
ARRIVAL OF STRONGER LARGE SCALE ASCENT.  THIS ASCENT/TSTMS SHOULD
MOVE NEWD NEAR/NORTH OF MAF AND INTO NWRN TX AND SWRN OK AFTER 03
UTC.  THUS...OTHER TSTMS ARE APT TO DEVELOP RAPIDLY IN THE NEXT
FEW HOURS...ESPECIALLY ALONG NWRN PERIPHERY OF RICHER MOISTURE
LOCATED FROM NEAR MAF-MIDWAY BETWEEN LBB/ABI-LAW-OKC.

INCREASING SLY LLJ BENEATH SWLY MIDLEVEL FLOW OVER 60 KTS WILL
CREATE A DEEP LAYER SHEAR PROFILE MORE THAN SUFFICIENT FOR
ORGANIZED SEVERE TSTMS.  IN FACT...GIVEN NEARLY 2100 J/KG MUCAPE
ON NORMAN 00Z SOUNDING...POTENTIAL WILL EXIST FOR SUPERCELLS WITH
MAINLY LARGE HAIL.  

ACTIVITY WILL INCREASE INTO ONE OR MORE MCS/S OVERNIGHT WITH A
CONTINUED LARGE HAIL AND DAMAGING WIND THREAT ACROSS NWRN TX INTO
CNTRL OK.

..RACY.. 04/19/2003

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...FWD...OUN...SJT...LUB...MAF...

32270220 34640015 35349910 35589775 35319721 34219767
32409996 31870139

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 18, 9:50 PM CDTSevere Thunderstorm WatchSPCBeckham, Caddo, Canadian, Cleveland, Comanche, Cotton and 13 more6 hr
Apr 18, 11:32 PM CDTMesoscale DiscussionSPCBeckham, Caddo, Canadian, Cleveland, Comanche, Cotton and 10 more118 min
Apr 19, 12:58 AM CDTMesoscale DiscussionSPCAlfalfa, Blaine, Custer, Dewey, Ellis, Garfield and 6 more2 hr
Apr 19, 1:20 AM CDTTornado WatchSPCComanche, Cotton, Greer, Harmon, Jackson, Kiowa and 2 more7 hr
Apr 19, 1:25 AM CDTSevere Thunderstorm WatchSPCAlfalfa, Beckham, Blaine, Caddo, Canadian, Cleveland and 18 more7 hr
Apr 19, 3:18 AM CDTMesoscale DiscussionSPCAdair, Atoka, Bryan, Cherokee, Choctaw, Coal and 30 more117 min
Apr 19, 4:11 AM CDTMesoscale DiscussionSPCComanche, Cotton, Jackson, Kiowa, Stephens, Tillman2 hr
Apr 19, 4:52 AM CDTMesoscale DiscussionSPCAlfalfa, Beckham, Blaine, Caddo, Canadian, Custer and 14 more113 min
Apr 19, 9:01 AM CDTMesoscale DiscussionSPCAdair, Atoka, Bryan, Cherokee, Choctaw, Coal and 19 more3 hr
Apr 19, 1:10 PM CDTMesoscale DiscussionSPCAlfalfa, Blaine, Canadian, Cleveland, Creek, Dewey and 18 more2 hr
Apr 19, 1:15 PM CDTTornado WatchSPCAlfalfa, Blaine, Canadian, Custer, Dewey, Ellis and 14 more7 hr
Apr 19, 2:02 PM CDTMesoscale DiscussionSPCAtoka, Bryan, Choctaw, Cleveland, Coal, Creek and 25 more88 min
Apr 19, 2:30 PM CDTTornado WatchSPCAtoka, Bryan, Cherokee, Choctaw, Coal, Craig and 32 more7 hr
Apr 19, 3:15 PM CDTMesoscale DiscussionSPCAtoka, Bryan, Choctaw, Cleveland, Coal, Creek and 25 more2 hr
Apr 19, 5:50 PM CDTMesoscale DiscussionSPCAlfalfa, Garfield, Grant, Kay, Kingfisher, Noble85 min
Apr 19, 6:07 PM CDTMesoscale DiscussionSPCAdair, Atoka, Cherokee, Choctaw, Coal, Craig and 27 more83 min
Apr 18, 9:21 PM CDTMesoscale DiscussionSPCBandera, Bexar, Blanco, Comal, Dimmit, Edwards and 12 more54 min

Nearby

Mesoscale Discussions in Texas, 2003Mesoscale Discussions in Oklahoma, 2003Every mesoscale discussion in 2003

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.