Alert archive / Texas / Mesoscale Discussions in 2011

Mesoscale Discussion 700

May 8, 20115 counties in Oklahoma; 15 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at May 8, 2011, 3:57 PM CDT for 5 counties in Oklahoma; 15 counties in Texas. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: May 8, 2011, 3:57 PM CDT (20:57 UTC)
Expired: May 8, 2011, 6:00 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center

Counties Comanche County, OK, Cotton County, OK, Jefferson County, OK, Stephens County, OK, Tillman County, OK, Archer County, TX, Baylor County, TX, Callahan County, TX, Clay County, TX, Coleman County, TX, Eastland County, TX, Jack County, TX, Jones County, TX, Palo Pinto County, TX, Shackelford County, TX, Stephens County, TX, Taylor County, TX, Throckmorton County, TX, Wichita County, TX, Young County, TX

The radar

The Altus AFB radar (KFDR), 90 km from the middle of the area, began a volume at 20:58 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 nearest sounding before it

Fort Worth, TX (KFWD), launched 12:00Z, 9.0 hours before the alert went out and 157 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: 1672 J/kg
Mixed-layer CIN: -498 J/kg
Mixed-layer LCL: 1190 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 236 m²/s²
0-3 km storm-relative helicity: 196 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.4

Open this sounding in Storm Lab

The text

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

400 
ACUS11 KWNS 082057
SWOMCD
SPC MCD 082057 
TXZ000-OKZ000-082300-

MESOSCALE DISCUSSION 0700
NWS STORM PREDICTION CENTER NORMAN OK
0357 PM CDT SUN MAY 08 2011

AREAS AFFECTED...PORTIONS OF SWRN OK AND WRN PORTIONS OF NORTH TX

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 082057Z - 082300Z

AN ISOLATED SVR STORM OR TWO COULD DEVELOP ACROSS PORTIONS OF SWRN
OK AND WRN PORTIONS OF NORTH TX.

A DRYLINE CONTINUES TO SHARPEN FROM CNTRL OK INTO WRN PORTIONS OF
NORTH TX...EXTENDING FROM 15 W CHK TO THE RED RIVER 20 W SPS TO 25
ENE SJT AND FARTHER SW INTO SWRN TX. A BROAD MOIST SECTOR EXISTS
EAST OF THE DRYLINE WHERE SFC DEWPOINTS ARE IN THE MIDDLE 60S TO
NEAR 70. OVERLAYING THIS MOISTURE...VERY STEEP MID-LEVEL LAPSE RATES
/APPROACHING DRY ADIABATIC PER 12Z OBSERVED SOUNDINGS AT KOUN AND
KDDC/ IN ASSOCIATION WITH THE STRONG ELEVATED MIXED-LAYER ARE
CONTRIBUTING TO A VERY UNSTABLE AIR MASS EAST OF THE DRYLINE /MLCAPE
VALUES AOA 3000 J PER KG/. THUS FAR...STRONG CAPPING EAST OF THE
DRYLINE IS SUPPRESSING THE DEVELOPMENT.

CONTINUED STRONG INSOLATION OVER THE WRN PERIPHERY OF THE RICH
MOISTURE AXIS AND ERN PERIPHERY OF THE THERMAL AXIS COULD REDUCE
CONVECTIVE INHIBITION SUFFICIENTLY TO SUPPORT THE DEVELOPMENT OF A
THUNDERSTORM OR TWO ALONG AND IMMEDIATELY EAST OF THE DRYLINE. THERE
IS MUCH UNCERTAINTY IN THIS POTENTIAL...OWING TO LACK OF SUPPORT
FROM CONVECTIVE-ALLOWING MODELS AND UNCERTAINTY IN THE DEGREE OF
SUPPRESSION OF CONVECTIVE INHIBITION. HOWEVER...THE PRESENCE OF A
DEVELOPING CUMULUS FIELD NEAR THE DRYLINE...WHERE ENHANCED
CONVERGENCE IS PRESENT AND RAPID REFRESH FORECAST SOUNDINGS INDICATE
CONVECTIVE INHIBITION AOB 25 J/KG...LEND CREDENCE TO THIS THREAT
/ALBEIT SMALL/.

ANY STORM THAT FORMS COULD QUICKLY BECOME SEVERE...GIVEN THE DEGREE
OF POTENTIAL UPWARD BUOYANCY PREVIOUSLY MENTIONED. WHILE
LOW/MID-LEVEL FLOW IS NOT PARTICULARLY IMPRESSIVE...MODERATE
UPPER-LEVEL FLOW COUPLED WITH LARGE STORM DEPTHS WILL YIELD
EFFECTIVE BULK SHEAR MAGNITUDES FROM 35 TO 40 KT TO SUPPORT
SUPERCELLULAR STRUCTURES. THIS WILL ESPECIALLY BE THE CASE IF ANY
STORM IS STEERED INTO THE DEEPER MOISTURE EAST OF THE DRYLINE. DMGG
WINDS AND LARGE HAIL /POTENTIALLY VERY LARGE/ WILL BE THE MAIN
THREATS WITH ANY STORMS. THE ABSENCE OF STRONGER LOW-LEVEL FLOW PER
AREA VWPS IS EXPECTED TO MITIGATE THE TORNADO POTENTIAL. GIVEN THAT
ANY FORCING FOR CONVECTION WILL LARGELY BE TIED TO THE DRYLINE
/WHICH IS EXPECTED TO MAKE LITTLE EWD PROGRESS THROUGH THIS
EVENING/...GIVEN THE CONVECTIVE INHIBITION EAST OF THE DRYLINE...AND
GIVEN ONLY ISOLATED CONVECTIVE COVERAGE...THE SPATIAL EXTENT OF ANY
SEVERE THREAT IS EXPECTED TO BE LOW.

..COHEN.. 05/08/2011

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

ATTN...WFO...FWD...OUN...SJT...

LAT...LON   33429790 32329846 31669960 31960020 32530008 33299963
            34299911 34759867 34949835 34929803 34809775 34219778
            33429790

Nearby

Mesoscale Discussions in Texas, 2011 Mesoscale Discussions in Oklahoma, 2011 Every mesoscale discussion in 2011

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.