Alert archive / Tennessee / Mesoscale Discussions in 2011

Mesoscale Discussion 147

February 27, 20115 states

The Storm Prediction Center issued this mesoscale discussion at Feb 27, 2011, 12:44 PM CST for 5 states. It was in force for 91 min.

The area

The outline as issued.

The facts

Issued: Feb 27, 2011, 12:44 PM CST (18:44 UTC)
Expired: Feb 27, 2011, 2:15 PM CST
In force: 91 min
Issued by: the Storm Prediction Center

All 30 counties

Crittenden County, AR, Cross County, AR, Lee County, AR, Mississippi County, AR, St. Francis County, AR, Fulton County, KY, Hickman County, KY, Pemiscot County, MO, DeSoto County, MS, Tate County, MS, Tunica County, MS, Benton County, TN, Carroll County, TN, Chester County, TN, Crockett County, TN, Decatur County, TN, Dyer County, TN, Fayette County, TN, Gibson County, TN, Hardeman County, TN, Haywood County, TN, Henderson County, TN, Henry County, TN, Lake County, TN, Lauderdale County, TN, Madison County, TN, Obion County, TN, Shelby County, TN, Tipton County, TN, Weakley County, TN

The radar

The Memphis radar (KNQA), 36 km from the middle of the area, began a volume at 18:44 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 12:00Z, 6.7 hours before the alert went out and 87 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: 58 J/kg
Mixed-layer CIN: -335 J/kg
Mixed-layer LCL: 849 m above ground
0-6 km bulk shear: 55 kt
0-1 km storm-relative helicity: 284 m²/s²
0-3 km storm-relative helicity: 287 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.

827 
ACUS11 KWNS 271845
SWOMCD
SPC MCD 271844
TNZ000-KYZ000-MSZ000-MOZ000-ARZ000-272015-

MESOSCALE DISCUSSION 0147
NWS STORM PREDICTION CENTER NORMAN OK
1244 PM CST SUN FEB 27 2011

AREAS AFFECTED...NERN AR / NWRN MS / WRN TN / MO BOOTHEEL / FAR WRN
KY

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 271844Z - 272015Z

NEXT 1-2 HRS WILL BE MONITORING FOR STORM DEVELOPMENT/SUSTENANCE
OVER NERN AR AND WRN TN AND A CONDITIONAL RISK FOR ISOLD TORNADOES.
IF/ONCE UPDRAFTS BECOME ROOTED IN THE BOUNDARY LAYER...AN ENSUING
ISOLD TORNADO THREAT WILL LIKELY EXIST.

RECENT VISIBLE SATELLITE IMAGERY SHOWS THINNING HIGHER LEVEL CLOUD
COVER ACROSS ERN AR EWD INTO NWRN MS AND WRN TN LEADING TO POCKETS
OF INCREASED HEATING.  IN THE LOW LEVELS...SURFACE TEMPS GENERALLY
NEAR AND S OF I-40 ARE IN THE LOWER 70S WITH DEWPOINTS RISING INTO
THE LOWER 60S WITHIN A MOIST PLUME EXTENDING UP THE MS RIVER VALLEY.
THIS IN TURN IS RESULTING IN 500-1000 J/KG MLCAPE AND A WEAKENED
CAP.  REPEATED CONVECTIVE ATTEMPTS INVOF THE MS/AR/TN BORDER MAY
EVENTUALLY BREACH THE REMAINING CAP AND LEADING TO ISOLD-SCTD STORMS
BY MID AFTERNOON.  THE LAST FEW RUNS OF THE HRRR HAVE SUGGESTED
SHALLOW CONVECTION NEAR MIDDAY WILL GRADUALLY DEEPEN BY 20Z.
IF/ONCE THIS OCCURS...SIZABLE CLOCKWISE CURVED LOW LEVEL HODOGRAPHS
PER NQA VAD DATA /30 KTS 0-1 KM SHEAR/ WITHIN AN INCREASINGLY
MOIST/DESTABILIZING BOUNDARY LAYER WILL SUPPORT UPDRAFT ROTATION AND
AN ATTENDANT TORNADO THREAT.

..SMITH.. 02/27/2011

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

ATTN...WFO...OHX...PAH...MEG...LZK...

LAT...LON   34709075 35179109 36728938 36678844 36298803 35578804
            34578999 34709075

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Feb 27, 4:57 PM CST	Mesoscale Discussion	SPC	Baxter, Boone, Carroll, Clay, Cleburne, Conway and 18 more	2 hr
Feb 27, 4:31 PM CST	Tornado Watch	SPC	Adair, Allen, Barren, Butler, Casey, Clinton and 11 more	3 hr
Feb 27, 12:46 PM CST	Mesoscale Discussion	SPC	Caldwell, Carroll, Cass, Chariton, Clay, Clinton and 7 more	59 min
Feb 27, 1:12 PM CST	Severe Thunderstorm Watch	SPC	Bates, Caldwell, Carroll, Cass, Chariton, Clay and 15 more	9 hr
Feb 27, 2:12 PM CST	Mesoscale Discussion	SPC	Barton, Dade, Jasper, Lawrence, Newton	93 min
Feb 27, 3:24 PM CST	Mesoscale Discussion	SPC	Bates, Carroll, Cass, Chariton, Clay, Cooper and 10 more	66 min
Feb 27, 5:10 PM CST	Mesoscale Discussion	SPC	Audrain, Boone, Macon, Marion, Monroe, Pike and 3 more	35 min
Feb 27, 5:33 PM CST	Severe Thunderstorm Watch	SPC	Audrain, Boone, Knox, Lewis, Marion, Monroe and 3 more	4 hr
Feb 27, 5:50 PM CST	Mesoscale Discussion	SPC	Harrison, Mercer, Putnam	6 hr

Nearby

Mesoscale Discussions in Tennessee, 2011 Mesoscale Discussions in Arkansas, 2011 Mesoscale Discussions in Mississippi, 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.