Alert archive / Arkansas / Mesoscale Discussions in 2012
Mesoscale Discussion 556
The Storm Prediction Center issued this mesoscale discussion at Apr 15, 2012, 7:28 PM CDT for 28 counties in Arkansas; 11 counties in Illinois; 20 counties in Missouri. It was in force for 62 min.
The area
The outline as issued.
The facts
- Issued
- Apr 15, 2012, 7:28 PM CDT (00:28 UTC)
- Expired
- Apr 15, 2012, 8:30 PM CDT
- In force
- 62 min
- Issued by
- the Storm Prediction Center
All 59 counties
Arkansas County, AR, Bradley County, AR, Calhoun County, AR, Clay County, AR, Cleburne County, AR, Cleveland County, AR, Craighead County, AR, Cross County, AR, Dallas County, AR, Desha County, AR, Drew County, AR, Grant County, AR, Greene County, AR, Independence County, AR, Jackson County, AR, Jefferson County, AR, Lawrence County, AR, Lincoln County, AR, Lonoke County, AR, Monroe County, AR, Ouachita County, AR, Poinsett County, AR, Prairie County, AR, Pulaski County, AR, Randolph County, AR, Sharp County, AR, White County, AR, Woodruff County, AR, Adams County, IL, Brown County, IL, Calhoun County, IL, Cass County, IL, Greene County, IL, Jersey County, IL, Monroe County, IL, Morgan County, IL, Pike County, IL, Schuyler County, IL, Scott County, IL, Butler County, MO, Carter County, MO, City of Saint Louis, MO, Franklin County, MO, Iron County, MO, Jefferson County, MO, Lincoln County, MO, Madison County, MO, Oregon County, MO, Pike County, MO, Reynolds County, MO, Ripley County, MO, Saint Charles County, MO, Saint Francois County, MO, Saint Louis County, MO, Sainte Genevieve County, MO, Shannon County, MO, Warren County, MO, Washington County, MO, Wayne County, MO
The radar
The Little Rock radar (KLZK), 84 km from the middle of the area, began a volume at 00:31 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
Little Rock, AR (KLZK), launched 00:00Z, 0.5 hours before the alert went out and 173 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.
- Mixed-layer CAPE
- 1081 J/kg
- Mixed-layer CIN
- -14 J/kg
- Mixed-layer LCL
- 1176 m above ground
- 0-6 km bulk shear
- 61 kt
- 0-1 km storm-relative helicity
- 389 m²/s²
- 0-3 km storm-relative helicity
- 497 m²/s²
- Significant tornado parameter
- 2.8
- Supercell composite
- 12.4
The text
As transmitted, in the capitals the NWS used until 2016.
934
ACUS11 KWNS 160028
SWOMCD
SPC MCD 160028
ILZ000-MOZ000-ARZ000-160130-
MESOSCALE DISCUSSION 0556
NWS STORM PREDICTION CENTER NORMAN OK
0728 PM CDT SUN APR 15 2012
AREAS AFFECTED...CNTRL/ERN AR...ERN MO...FAR WRN IL
CONCERNING...TORNADO WATCH 179...180...
VALID 160028Z - 160130Z
THE SEVERE WEATHER THREAT FOR TORNADO WATCH 179...180...CONTINUES.
A LOOSELY ORGANIZED QLCS CONTINUES TO PROGRESS EWD ACROSS ERN
MO/AR...WITH RADAR REFLECTIVITY INDICATING OCCASIONAL EMBEDDED
CIRCULATIONS CAPABLE OF ENHANCING WIND GUSTS...BUT A SLOW WEAKENING
TREND HAS BEEN NOTED IN RECENT SCANS. KINEMATIC ENVIRONMENT
ALONG/AHEAD OF CONVECTIVE LINE CONTINUES TO REMAIN FAVORABLE FOR
DMGG WIND GUSTS AND ISOLATED TORNADOES...WITH BOTH ILX/LSX VWP DATA
SHOWING VERY STRONGLY SHEARED PROFILES /0-1 KM HELICITY GREATER THAN
500 M^2/S^2/. PRIMARY FACTOR THAT APPEARS TO BE INHIBITING A MORE
ORGANIZED/WIDESPREAD THREAT ATTM IS MARGINAL INSTABILITY DOWNSTREAM
FROM ONGOING CONVECTION. 00Z SOUNDING FROM ILX INDICATED AROUND 400
J/KG OF MLCAPE...WITH POOR LAPSE RATES OBSERVED WITHIN THE 1-3 KM
AGL LAYER. HOWEVER...ACTIVITY SHOULD REMAIN NEAR-SFC BASED PAST
SUNSET...AND WITH PERSISTENCE OF A STRONG LOW-LEVEL JET ALONG WITH
MID/UPPER FORCING FOR ASCENT ACCOMPANYING AN UPSTREAM UPPER TROUGH
MOVING TOWARDS THE AREA...AT LEAST SOME THREAT FOR DMGG
WINDS/ISOLATED TORNADOES SHOULD CONTINUE.
..ROGERS.. 04/16/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...PAH...ILX...MEG...JAN...LSX...DVN...LZK...SGF...
SHV...
LAT...LON 33639130 33309166 33219292 33489323 33689314 34359259
37579129 40209122 40208994 36569017 33639130Nearby
Mesoscale Discussions in Arkansas, 2012Mesoscale Discussions in Missouri, 2012Mesoscale Discussions in Illinois, 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.