Alert archive / Tennessee / Mesoscale Discussions in 2012

Mesoscale Discussion 143

February 22, 201212 counties in Alabama; Catoosa County, Dade County, Walker County, Georgia; 24 counties in Tennessee

The Storm Prediction Center issued this mesoscale discussion at Feb 22, 2012, 5:49 PM CST for 12 counties in Alabama; Catoosa County, Dade County, Walker County, Georgia; 24 counties in Tennessee. It was in force for 86 min.

The area

The outline as issued.

The facts

Issued: Feb 22, 2012, 5:49 PM CST (23:49 UTC)
Expired: Feb 22, 2012, 7:15 PM CST
In force: 86 min
Issued by: the Storm Prediction Center

All 39 counties

Blount County, AL, Cullman County, AL, DeKalb County, AL, Etowah County, AL, Jackson County, AL, Lawrence County, AL, Limestone County, AL, Madison County, AL, Marshall County, AL, Morgan County, AL, Walker County, AL, Winston County, AL, Catoosa County, GA, Dade County, GA, Walker County, GA, Bedford County, TN, Bledsoe County, TN, Bradley County, TN, Cannon County, TN, Coffee County, TN, Cumberland County, TN, DeKalb County, TN, Fentress County, TN, Franklin County, TN, Grundy County, TN, Hamilton County, TN, Lincoln County, TN, Marion County, TN, Meigs County, TN, Moore County, TN, Morgan County, TN, Overton County, TN, Putnam County, TN, Rhea County, TN, Roane County, TN, Sequatchie County, TN, Van Buren County, TN, Warren County, TN, White County, TN

The radar

The Northeast Alabama radar (KHTX), 21 km from the middle of the area, began a volume at 23:49 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

Nashville Metro, TN (KBNA), launched 12:00Z, 11.8 hours before the alert went out and 139 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 2212 m above ground
0-6 km bulk shear: 91 kt
0-1 km storm-relative helicity: 217 m²/s²
0-3 km storm-relative helicity: 295 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.

100 
ACUS11 KWNS 222350
SWOMCD
SPC MCD 222349
TNZ000-GAZ000-ALZ000-230115-

MESOSCALE DISCUSSION 0143
NWS STORM PREDICTION CENTER NORMAN OK
0549 PM CST WED FEB 22 2012

AREAS AFFECTED...NE AL...SE TN...FAR NW AL

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 222349Z - 230115Z

AN ISOLATED SEVERE THREAT WILL LIKELY INCREASE SOME OVER THE NEXT
FEW HOURS FROM MIDDLE TO ERN TN SWD ACROSS NRN AL AND FAR NW GA.
HAIL AND WIND DAMAGE WILL BE POSSIBLE. WW ISSUANCE MAY BE NECESSARY
ACROSS THE REGION.

A LINE OF STRONG THUNDERSTORMS IS ONGOING ALONG AN AXIS OF
INSTABILITY WHERE MESOANALYSIS SHOWS MUCAPE VALUES FROM 250 TO 750
J/KG. THE STORMS ARE DEVELOPING IN A STRONGLY SHEARED ENVIRONMENT
WITH WSR-88D-VWPS SHOWING 0-6 KM SHEAR VALUES OF 70 TO 80 KT. THIS
COMBINED WITH INCREASING LARGE-SCALE ASCENT AS A SHORTWAVE TROUGH
APPROACHES FROM THE WEST AND STEEP MID-LEVEL LAPSE RATES OF 7.0 TO
7.5 C/KM SHOULD BE SUFFICIENT FOR A HAIL THREAT WITH THE STRONGER
CORES EMBEDDED IN THE LINE. EWD STORM MOTION OF 40 KT WILL HELP
CREATE A WIND DAMAGE THREAT ESPECIALLY AS THE LINE BECOMES NEARLY
CONTINUOUS. SUPERCELLS WITH AN ISOLATED TORNADO THREAT MAY ALSO
EXIST ON THE SRN END OF THE LINE WHERE INSTABILITY IS MAXIMIZED AND
THE LOW-LEVEL JET IS FORECAST TO STRENGTHEN EARLY THIS EVENING.

..BROYLES.. 02/22/2012

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

ATTN...WFO...MRX...FFC...OHX...BMX...HUN...

LAT...LON   35928438 36378455 36558536 35888624 34918734 34258779
            33898760 33648692 33748625 34138579 34718521 35348467
            35928438

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Feb 22, 2:08 PM CST	Mesoscale Discussion	SPC	Bibb, Blount, Calhoun, Cherokee, Cleburne, Colbert and 23 more	2 hr

Nearby

Mesoscale Discussions in Tennessee, 2012 Mesoscale Discussions in Alabama, 2012 Mesoscale Discussions in Georgia, 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.