Alert archive / Arkansas / Mesoscale Discussions in 2012

Mesoscale Discussion 449

April 4, 20124 states

The Storm Prediction Center issued this mesoscale discussion at Apr 4, 2012, 8:31 PM CDT for 4 states. It was in force for 119 min.

The area

The outline as issued.

The facts

Issued
Apr 4, 2012, 8:31 PM CDT (01:31 UTC)
Expired
Apr 4, 2012, 10:30 PM CDT
In force
119 min
Issued by
the Storm Prediction Center
All 46 counties

Calhoun County, AR, Clark County, AR, Columbia County, AR, Conway County, AR, Crawford County, AR, Dallas County, AR, Franklin County, AR, Garland County, AR, Grant County, AR, Hempstead County, AR, Hot Spring County, AR, Howard County, AR, Johnson County, AR, Lafayette County, AR, Little River County, AR, Logan County, AR, Miller County, AR, Montgomery County, AR, Nevada County, AR, Ouachita County, AR, Perry County, AR, Pike County, AR, Polk County, AR, Pope County, AR, Saline County, AR, Scott County, AR, Sebastian County, AR, Sevier County, AR, Union County, AR, Yell County, AR, Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Claiborne Parish, LA, De Soto Parish, LA, Lincoln Parish, LA, Red River Parish, LA, Webster Parish, LA, LeFlore County, OK, McCurtain County, OK, Bowie County, TX, Cass County, TX, Harrison County, TX, Marion County, TX, Morris County, TX, Panola County, TX

The radar

The Western Arkansas radar (KSRX), 157 km from the middle of the area, began a volume at 01:31 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 00:00Z, 1.5 hours before the alert went out and 164 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 00:00Z on 2012-04-05Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 439 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 00:00Z on 2012-04-05The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 30 square meters per square second.1939587897Sfc1 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
439 J/kg
Mixed-layer CIN
-39 J/kg
Mixed-layer LCL
1639 m above ground
0-6 km bulk shear
56 kt
0-1 km storm-relative helicity
30 m²/s²
0-3 km storm-relative helicity
135 m²/s²
Significant tornado parameter
0.1
Supercell composite
1.2

Open this sounding in Storm Lab

The text

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

944 
ACUS11 KWNS 050132
SWOMCD
SPC MCD 050131
ARZ000-LAZ000-TXZ000-OKZ000-050330-

MESOSCALE DISCUSSION 0449
NWS STORM PREDICTION CENTER NORMAN OK
0831 PM CDT WED APR 04 2012

AREAS AFFECTED...SERN OK...WRN/CNTRL AR...NERN TX...NWRN LA

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 050131Z - 050330Z

SCATTERED THUNDERSTORMS ARE FORECAST TO DEVELOP DURING THE NEXT FEW
HRS ACROSS SERN OK...WRN AR...NERN TX...AND NWRN LA. ALTHOUGH THE
OVERALL THREAT FOR SEVERE STORMS APPEARS LOW...SOME STORMS MAY
PRODUCE DMGG WINDS AND MARGINALLY SEVERE HAIL.

00Z LZK AND SHV SOUNDINGS DEPICT AN UNSTABLE ENVIRONMENT WITH MUCAPE
VALUES AOA 1300 J/KG AND STEEP LAPSE RATES ABOVE 700MB. LIFT IS
EXPECTED TO INCREASE ACROSS THE AREA AS THE UPPER LEVEL LOW CENTERED
OVER CNTRL OK PROGRESSES EWD. ADDITIONALLY... EFFECTIVE BULK SHEAR
VALUES ABOVE 40 KTS SUGGEST STORM ORGANIZATION IS POSSIBLE.
HOWEVER...SURFACE TEMPERATURES WILL CONTINUE TO DECREASE WITH A
RESULTANT DECREASE IN INSTABILITY AND INCREASE IN CIN. AS A
RESULT...THE COVERAGE OF STORMS IS EXPECTED TO BE LIMITED. WITH ANY
STORMS THAT DO DEVELOP...MARGINALLY SEVERE HAIL IS THE PRIMARY
THREAT BUT DMGG WIND GUSTS WILL ALSO BE POSSIBLE. THE APPROACHING
UPPER LOW WILL ALSO INCREASE VERTICAL VORTICITY VALUES BUT WEAK LOW
LEVEL FLOW AND THE NOCTURNAL INVERSION SHOULD KEEP THE OVERALL
TORNADO THREAT VERY LOW.

..MOSIER.. 04/05/2012

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

ATTN...WFO...LZK...SHV...TSA...

LAT...LON   35399474 35899441 35909334 35739261 34969237 34199236
            32649251 32209300 31949351 31949426 32179460 32569472
            33799500 34609502 35399474

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 5, 1:35 AM CDTMesoscale DiscussionSPCAshley, Chicot85 min
Apr 5, 1:53 AM CDTTornado WatchSPCAshley, Chicot9 hr
Apr 5, 3:30 AM CDTMesoscale DiscussionSPCAshley, Chicot, Union2 hr
Apr 5, 7:36 AM CDTMesoscale DiscussionSPCChicot54 min
Apr 5, 12:09 PM CDTMesoscale DiscussionSPCClay, Craighead, Crittenden, Greene, Mississippi, Randolph96 min
Apr 5, 12:18 PM CDTSevere Thunderstorm WatchSPCCrittenden, Mississippi5 hr
Apr 4, 8:25 PM CDTMesoscale DiscussionSPCAcadia, Allen, Ascension, Assumption, Beauregard, Calcasieu and 21 more95 min
Apr 5, 3:56 AM CDTTornado WatchSPCAscension, Assumption, East Baton Rouge, East Feliciana, Iberville, Jefferson and 16 more6 hr

Nearby

Mesoscale Discussions in Arkansas, 2012Mesoscale Discussions in Louisiana, 2012Mesoscale Discussions in Texas, 2012Every mesoscale discussion in 2012

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.