Alert archive / Arkansas / Mesoscale Discussions in 2011

Mesoscale Discussion 574

April 25, 201135 counties in Arkansas; 6 parishes in Louisiana

The Storm Prediction Center issued this mesoscale discussion at Apr 25, 2011, 3:08 PM CDT for 35 counties in Arkansas; 6 parishes in Louisiana. It was in force for 37 min.

The area

The outline as issued.

The facts

Issued
Apr 25, 2011, 3:08 PM CDT (20:08 UTC)
Expired
Apr 25, 2011, 3:45 PM CDT
In force
37 min
Issued by
the Storm Prediction Center
All 41 counties

Arkansas County, AR, Ashley County, AR, Baxter County, AR, Boone County, AR, Bradley County, AR, Calhoun County, AR, Cleburne County, AR, Cleveland County, AR, Columbia County, AR, Conway County, AR, Dallas County, AR, Drew County, AR, Faulkner County, AR, Grant County, AR, Hot Spring County, AR, Independence County, AR, Izard County, AR, Jefferson County, AR, Johnson County, AR, Lincoln County, AR, Lonoke County, AR, Madison County, AR, Marion County, AR, Newton County, AR, Ouachita County, AR, Pope County, AR, Prairie County, AR, Pulaski County, AR, Saline County, AR, Searcy County, AR, Sharp County, AR, Stone County, AR, Union County, AR, Van Buren County, AR, White County, AR, Bienville Parish, LA, Claiborne Parish, LA, Lincoln Parish, LA, Ouachita Parish, LA, Union Parish, LA, Webster Parish, LA

The radar

The Little Rock radar (KLZK), 65 km from the middle of the area, began a volume at 20:08 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

Shreveport, LA (KSHV), launched 12:00Z, 8.1 hours before the alert went out and 251 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, Shreveport, LA at 12:00Z on 2011-04-25Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1213 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Shreveport, LA at 12:00Z on 2011-04-25The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 231 square meters per square second.19395878Sfc1 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
1213 J/kg
Mixed-layer CIN
-34 J/kg
Mixed-layer LCL
759 m above ground
0-6 km bulk shear
44 kt
0-1 km storm-relative helicity
231 m²/s²
0-3 km storm-relative helicity
491 m²/s²
Significant tornado parameter
2.2
Supercell composite
11.5

Open this sounding in Storm Lab

The text

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

440 
ACUS11 KWNS 252009
SWOMCD
SPC MCD 252008
ARZ000-LAZ000-252045-

MESOSCALE DISCUSSION 0574
NWS STORM PREDICTION CENTER NORMAN OK
0308 PM CDT MON APR 25 2011

AREAS AFFECTED...MUCH OF AR/NORTHERN LA

CONCERNING...SEVERE POTENTIAL...WATCH NEEDED SOON

VALID 252008Z - 252045Z

AN ADDITIONAL TORNADO WATCH WILL BE ISSUED SOON FOR NORTHERN/CENTRAL
PORTIONS OF AR AND NORTHERN LA.

THE AIRMASS CONTINUES TO DESTABILIZE ALONG/SOUTH OF A MODIFYING
WEST-EAST OUTFLOW BOUNDARY ACROSS AR AMID A REGIONAL OF STRONG
SURFACE PRESSURE FALLS...WITH ADDITIONAL DESTABILIZATION /ALBEIT
MODEST/ EXPECTED INTO NORTHERN AR AS THE AFOREMENTIONED BOUNDARY
MIXES/SHIFTS NORTHWARD AS AN EFFECTIVE WARM FRONT. AS SAMPLED BY THE
18Z LITTLE ROCK OBSERVED RAOB...STRONG SHEAR WILL CONTINUE TO
SUPPORT A THREAT FOR TORNADOES /PERHAPS SOME STRONG/...IN ADDITION
TO SEVERE HAIL/DAMAGING WINDS.

..GUYER.. 04/25/2011

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

ATTN...WFO...MEG...JAN...LZK...SHV...TSA...

LAT...LON   35719429 36389336 36239127 33909123 32309223 32359372
            33749308 35369283 35719429

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 24, 10:13 PM CDTMesoscale DiscussionSPCClark, Cleburne, Conway, Faulkner, Garland, Grant and 15 more2 hr
Apr 24, 11:43 PM CDTSevere Thunderstorm WatchSPCHempstead, Howard, Little River, Miller, Nevada, Sevier5 hr
Apr 25, 1:57 AM CDTMesoscale DiscussionSPCCleveland, Dallas, Jefferson, Lincoln63 min
Apr 25, 4:41 AM CDTSevere Thunderstorm WatchSPCArkansas, Bradley, Calhoun, Clark, Cleveland, Columbia and 25 more7 hr
Apr 25, 7:23 AM CDTMesoscale DiscussionSPCCalhoun, Clark, Cleveland, Columbia, Dallas, Garland and 11 more97 min
Apr 25, 8:37 AM CDTMesoscale DiscussionSPCArkansas, Cleveland, Crittenden, Desha, Drew, Jefferson and 7 more53 min
Apr 25, 9:17 AM CDTSevere Thunderstorm WatchSPCCrittenden, Lee, Phillips, St. Francis6 hr
Apr 25, 10:46 AM CDTMesoscale DiscussionSPCHempstead, Howard, Lafayette, Little River, Miller, Sevier59 min
Apr 25, 11:00 AM CDTTornado WatchSPCCarroll, Clark, Crawford, Franklin, Hempstead, Howard and 13 more7 hr
Apr 25, 1:15 PM CDTMesoscale DiscussionSPCCrittenden, Cross, Lee, Phillips, St. Francis60 min
Apr 25, 1:28 PM CDTMesoscale DiscussionSPCCrawford, Franklin, Howard, Johnson, Little River, Logan and 5 more92 min
Apr 25, 3:22 PM CDTTornado Watch PDSSPCArkansas, Baxter, Boone, Bradley, Calhoun, Clark and 50 more8 hr
Apr 25, 4:34 PM CDTMesoscale DiscussionSPCArkansas, Clay, Craighead, Crittenden, Cross, Greene and 11 more56 min
Apr 25, 4:50 PM CDTTornado Watch PDSSPCClay, Craighead, Crittenden, Cross, Greene, Lee and 4 more7 hr

Nearby

Mesoscale Discussions in Arkansas, 2011Mesoscale Discussions in Louisiana, 2011Every 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.