Alert archive / Arkansas / Mesoscale Discussions in 2011

Mesoscale Discussion 271

March 25, 201121 counties in Arkansas; 13 counties in Oklahoma; 15 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Mar 25, 2011, 3:43 PM CDT for 21 counties in Arkansas; 13 counties in Oklahoma; 15 counties in Texas. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued: Mar 25, 2011, 3:43 PM CDT (20:43 UTC)
Expired: Mar 25, 2011, 6:15 PM CDT
In force: 3 hr
Issued by: the Storm Prediction Center

All 49 counties

Calhoun County, AR, Clark County, AR, Cleveland County, AR, Columbia County, AR, Dallas County, AR, Garland County, AR, Grant County, AR, Hempstead County, AR, Hot Spring County, AR, Howard County, AR, Lafayette County, AR, Little River County, AR, Miller County, AR, Montgomery County, AR, Nevada County, AR, Ouachita County, AR, Pike County, AR, Polk County, AR, Scott County, AR, Sevier County, AR, Union County, AR, Atoka County, OK, Bryan County, OK, Choctaw County, OK, Coal County, OK, Johnston County, OK, Latimer County, OK, LeFlore County, OK, Love County, OK, Marshall County, OK, McCurtain County, OK, Pittsburg County, OK, Pontotoc County, OK, Pushmataha County, OK, Bowie County, TX, Cass County, TX, Collin County, TX, Cooke County, TX, Delta County, TX, Denton County, TX, Fannin County, TX, Franklin County, TX, Grayson County, TX, Hopkins County, TX, Hunt County, TX, Lamar County, TX, Morris County, TX, Red River County, TX, Titus County, TX

The radar

The Western Arkansas radar (KSRX), 148 km from the middle of the area, began a volume at 20:45 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

Shreveport, LA (KSHV), launched 12:00Z, 8.7 hours before the alert went out and 179 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1356 m above ground
0-6 km bulk shear: 44 kt
0-1 km storm-relative helicity: 244 m²/s²
0-3 km storm-relative helicity: 471 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.

685 
ACUS11 KWNS 252044
SWOMCD
SPC MCD 252043
ARZ000-LAZ000-TXZ000-OKZ000-252315-

MESOSCALE DISCUSSION 0271
NWS STORM PREDICTION CENTER NORMAN OK
0343 PM CDT FRI MAR 25 2011

AREAS AFFECTED...NCNTRL/NERN TX...SCNTRL/SERN OK...SWRN AR AND
EXTREME NRN LA

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 252043Z - 252315Z

LATEST VISIBLE SATELLITE IMAGERY DEPICTS A DEEPENING CUMULUS FIELD
ACROSS THE WARM SECTOR OVER SCNTRL/SERN OK AND NCNTRL TX.
HOWEVER...RIDGE/ANTICYCLONIC CHARACTER TO HIGH-LEVEL CLOUDS MOVING
OVER THE REGION AND LACK OF SUBSTANTIAL LOW-LEVEL CONVERGENCE WILL
PROBABLY BE DETRIMENTAL TO SURFACE-BASED CONVECTIVE INITIATION UNTIL
AFTER 23Z OR SO.  THEREAFTER...WEAK HEIGHT FALLS ASSOCIATED WITH AN
UPSTREAM TROUGH AND THE PRE-EXISTING WARM BOUNDARY LAYER MAY BECOME
SLIGHTLY MORE FAVORABLE FOR INITIATION.  THERE APPEARS TO BE ENOUGH
EVIDENCE TO SUPPORT LATEST RUC/GFS/NAM SOLUTIONS FOR AT LEAST
ISOLATED THUNDERSTORMS NEAR THE TRIPLE POINT AND SWD ALONG THE
DRYLINE FROM SCNTRL OK INTO NCNTRL TX NEAR SUNSET WHERE NRN-EXTENT
OF 1000-1500 J/KG MLCAPES WILL EXIST.

SHOULD A STORM FORM...ROUGHLY 45-50 KTS OF LARGELY UNIDIRECTIONAL
DEEP-LAYER SHEAR AND MID-LEVEL LAPSE RATES IN EXCESS OF 7 DEG C PER
KM WILL BE FAVORABLE FOR SPLITTING SUPERCELLS CAPABLE OF LARGE HAIL.
 A SUSTAINED SURFACE-BASED STORM EVOLVING ALONG/N OF THE RED RIVER
NEAR A WARM FRONT COULD PRODUCE A TORNADO OR TWO...BUT THE HAIL RISK
WILL DOMINATE.

OTHERWISE...ADDITIONAL ACTIVITY IS EXPECTED TO EVOLVE AND/OR DEVELOP
ALONG/N OF THE WARM FRONT AS ELEVATED ENTITIES OVER ERN OK AND CNTRL
AR LATER THIS EVENING WITH POSSIBLE LARGE HAIL.

..RACY.. 03/25/2011

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

ATTN...WFO...LZK...SHV...TSA...FWD...OUN...

LAT...LON   34999665 35109584 35109495 35009416 34809321 34549253
            34199211 33739205 33259247 33019274 32869331 32869407
            32989476 33099575 32989763 33939733 34999665

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Mar 24, 7:09 PM CDT	Mesoscale Discussion	SPC	Borden, Briscoe, Coke, Cottle, Crosby, Dawson and 22 more	96 min

Nearby

Mesoscale Discussions in Arkansas, 2011 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.