Alert archive / Arkansas / Mesoscale Discussions in 2012

Mesoscale Discussion 45

January 22, 20124 states

The Storm Prediction Center issued this mesoscale discussion at Jan 22, 2012, 2:26 PM CST for 4 states. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Jan 22, 2012, 2:26 PM CST (20:26 UTC)
Expired: Jan 22, 2012, 4:30 PM CST
In force: 2 hr
Issued by: the Storm Prediction Center

All 61 counties

Arkansas County, AR, Ashley County, AR, Bradley County, AR, Calhoun County, AR, Chicot County, AR, Clark County, AR, Cleveland County, AR, Columbia County, AR, Craighead County, AR, Crittenden County, AR, Cross County, AR, Dallas County, AR, Desha County, AR, Drew County, AR, Grant County, AR, Hempstead County, AR, Jackson County, AR, Jefferson County, AR, Lafayette County, AR, Lee County, AR, Lincoln County, AR, Lonoke County, AR, Miller County, AR, Monroe County, AR, Nevada County, AR, Ouachita County, AR, Phillips County, AR, Poinsett County, AR, Prairie County, AR, Pulaski County, AR, St. Francis County, AR, Union County, AR, White County, AR, Woodruff County, AR, Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Caldwell Parish, LA, Claiborne Parish, LA, De Soto Parish, LA, East Carroll Parish, LA, Franklin Parish, LA, Jackson Parish, LA, Lincoln Parish, LA, Morehouse Parish, LA, Ouachita Parish, LA, Red River Parish, LA, Richland Parish, LA, Union Parish, LA, Webster Parish, LA, West Carroll Parish, LA, Bolivar County, MS, Coahoma County, MS, DeSoto County, MS, Quitman County, MS, Sunflower County, MS, Tate County, MS, Tunica County, MS, Washington County, MS, Shelby County, TN, Tipton County, TN

The radar

The Little Rock radar (KLZK), 116 km from the middle of the area, began a volume at 20:30 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.

Tornado Watch 5Jan 22, 5:20 PM CST

The nearest sounding before it

Shreveport, LA (KSHV), launched 12:00Z, 8.4 hours before the alert went out and 200 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: 7 J/kg
Mixed-layer CIN: -107 J/kg
Mixed-layer LCL: 463 m above ground
0-6 km bulk shear: 40 kt
0-1 km storm-relative helicity: 228 m²/s²
0-3 km storm-relative helicity: 323 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

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

470 
ACUS11 KWNS 222027
SWOMCD
SPC MCD 222026
TNZ000-ARZ000-MSZ000-LAZ000-TXZ000-222230-

MESOSCALE DISCUSSION 0045
NWS STORM PREDICTION CENTER NORMAN OK
0226 PM CST SUN JAN 22 2012

AREAS AFFECTED...NERN TX...NRN LA...SRN/ERN AR...NWRN MS...WRN TN

CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY

VALID 222026Z - 222230Z

SEVERE THUNDERSTORMS SHOULD INITIATE BY EARLY EVENING NEAR THE
ARKLATEX THEN RACE NEWD TOWARD WRN TN/NWRN MS AFTER DARK.  DAMAGING
WINDS AND ISOLATED TORNADOES ARE EXPECTED.  A TORNADO WATCH WILL
LIKELY BE REQUIRED BY 00Z.

LEADING EDGE OF WELL DEFINED UPPER TROUGH IS ADVANCING ACROSS ERN
OK/NERN TX AND WILL SOON OVERSPREAD THE LOWER MS VALLEY.  IN ADVANCE
OF THIS FEATURE...WARM MOIST BOUNDARY LAYER HAS SPREAD INTO SRN/ERN
AR...AS NOTED BY SFC DEW POINTS RISING THROUGH THE UPPER 50S INTO
THE 60S...WHILE A STUBBORN WEDGE OF COOLER AIR HAS YET TO BE
DISPLACED OVER MUCH OF CNTRL/NWRN AR.  CURRENT THINKING IS GREATEST
AIRMASS DESTABILIZATION WILL OCCUR TO THE S-E OF THE AFOREMENTIONED
WEDGE FRONT AND THIS WILL BE THE CORRIDOR OF GREATEST SEVERE
THUNDERSTORM POTENTIAL.

LATEST VIS IMAGERY DEPICTS AN INCREASING BAND OF LOW LEVEL CU ALONG
THE DRY LINE NEAR I-35 OVER NCNTRL TX.  THIS IS ALONG THE LEADING
EDGE OF STEEPER LAPSE RATES AND IS CERTAINLY INDICATIVE OF STRONGER
FORCING THAT WILL SOON OVERSPREAD THE ARKLATEX.  WITH TIME
THUNDERSTORMS COULD EVOLVE ALONG THIS LINE...OR PERHAPS EVEN DEVELOP
WELL AHEAD OF THE WIND SHIFT WITHIN DEEPER CONFLUENT ZONE NEAR THE
LA BORDER AS EXHIBITED BY SHOWERS BEGINNING TO DEEPEN FROM NEAR TYR
TO JUST WEST OF SHV.  NEEDLESS TO SAY VERY STRONG SHEAR WILL SUPPORT
SUPERCELL DEVELOPMENT AND THE POTENTIAL FOR TORNADOES.

..DARROW.. 01/22/2012

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

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

LAT...LON   33369442 34409266 36039130 35608952 33729030 32089160
            31789398 33369442

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jan 22, 5:16 PM CST	Tornado Watch PDS	SPC	Arkansas, Ashley, Bradley, Calhoun, Chicot, Clay and 29 more	6 hr

Nearby

Mesoscale Discussions in Arkansas, 2012 Mesoscale Discussions in Louisiana, 2012 Mesoscale Discussions in Mississippi, 2012 Every 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.