Alert archive / Alabama / Mesoscale Discussions in 2011

Mesoscale Discussion 178

February 28, 201118 counties in Alabama; 6 counties in Florida; 4 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Feb 28, 2011, 5:16 PM CST for 18 counties in Alabama; 6 counties in Florida; 4 counties in Mississippi. It was in force for 89 min.

The area

The outline as issued.

The facts

Issued: Feb 28, 2011, 5:16 PM CST (23:16 UTC)
Expired: Feb 28, 2011, 6:45 PM CST
In force: 89 min
Issued by: the Storm Prediction Center

All 28 counties

Baldwin County, AL, Barbour County, AL, Butler County, AL, Clarke County, AL, Coffee County, AL, Conecuh County, AL, Covington County, AL, Crenshaw County, AL, Dale County, AL, Escambia County, AL, Geneva County, AL, Henry County, AL, Houston County, AL, Mobile County, AL, Monroe County, AL, Pike County, AL, Washington County, AL, Wilcox County, AL, Escambia County, FL, Holmes County, FL, Okaloosa County, FL, Santa Rosa County, FL, Walton County, FL, Washington County, FL, George County, MS, Greene County, MS, Jackson County, MS, Perry County, MS

The radar

The Eglin Afb radar (KEVX), 114 km from the middle of the area, began a volume at 23:17 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

Birmingham, AL (KBMX), launched 12:00Z, 11.3 hours before the alert went out and 217 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: 652 J/kg
Mixed-layer CIN: -2 J/kg
Mixed-layer LCL: 498 m above ground
0-6 km bulk shear: 60 kt
0-1 km storm-relative helicity: 256 m²/s²
0-3 km storm-relative helicity: 425 m²/s²
Significant tornado parameter: 1.3
Supercell composite: 5.9

Open this sounding in Storm Lab

The text

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

327 
ACUS11 KWNS 282317
SWOMCD
SPC MCD 282316
GAZ000-FLZ000-ALZ000-MSZ000-010045-

MESOSCALE DISCUSSION 0178
NWS STORM PREDICTION CENTER NORMAN OK
0516 PM CST MON FEB 28 2011

AREAS AFFECTED...FAR SERN MS...SRN AL...WRN PORTIONS OF THE FL
PANHANDLE

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 282316Z - 010045Z

THE THREAT FOR THUNDERSTORMS PRODUCING DAMAGING WINDS WILL OCCUR
THIS AFTERNOON INTO EARLY EVENING ACROSS FAR SERN MS...SRN AL...AND
WRN PORTIONS OF THE FL PANHANDLE. AN ISOLATED TORNADO CANNOT BE
RULED OUT. A WW IS POSSIBLE.

A SFC COLD FRONT DRAPED FROM CNTRL AL ACROSS SERN MS AND INTO SERN
LA WILL CONTINUE ADVANCING SEWD THIS AFTERNOON INTO THIS EVENING.
AHEAD OF THE BOUNDARY...SFC DEWPOINTS IN THE UPPER 60S TO NEAR 70
DEGREES ARE SUPPORTING SBCAPE VALUES OF 1000-2000 J/KG PER 22Z RUC
ANALYSIS. AS SUCH...CONVECTION CONTINUES TO INITIATE AND DEEPEN
ALONG AND AHEAD OF THE FRONT ACROSS PORTIONS OF SRN AL AND SERN MS.
MODERATE TO STRONG MID-LEVEL FLOW ACROSS THE REGION WILL CONTINUE
SUPPORTING EFFECTIVE BULK SHEAR MAGNITUDES OF 50-55 KT...WHICH WILL
FAVOR ORGANIZED CONVECTION. GENERALLY STRAIGHT-LINE HODOGRAPHS INVOF
THE FRONT WILL SUPPORT A PRIMARY LINEAR CONVECTIVE MODE...WITH AN
ATTENDANT THREAT FOR DAMAGING WINDS. HOWEVER...WITH STRONG LOW-LEVEL
SPEED SHEAR IN PLACE /20-30 KT OF 0-1 KM BULK SHEAR PER RUC
ANALYSIS/...AN ISOLATED TORNADO CANNOT BE RULED OUT. THIS WILL
ESPECIALLY BE THE CASE WITH ANY CONVECTION WELL AHEAD OF THE SFC
BOUNDARY...WHERE SFC FLOW WILL BE RELATIVELY MORE BACKED YIELDING
GREATER LOW-LEVEL HODOGRAPH CURVATURE.

..COHEN.. 02/28/2011

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

ATTN...WFO...TAE...BMX...MOB...LIX...

LAT...LON   31618865 32028751 31988615 32148541 31898508 31328510
            30918515 30478546 30348630 30268742 30328888 31058910
            31618865

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Feb 28, 5:47 AM CST	Mesoscale Discussion	SPC	Colbert, Franklin, Jackson, Lamar, Lauderdale, Lawrence and 5 more	28 min
Feb 28, 5:59 AM CST	Tornado Watch	SPC	Colbert, Cullman, DeKalb, Fayette, Franklin, Jackson and 10 more	7 hr
Feb 28, 11:25 AM CST	Mesoscale Discussion	SPC	Blount, Colbert, Cullman, DeKalb, Fayette, Franklin and 11 more	95 min
Feb 28, 12:19 PM CST	Mesoscale Discussion	SPC	Autauga, Baldwin, Barbour, Bullock, Butler, Clarke and 15 more	86 min
Feb 28, 12:29 PM CST	Tornado Watch	SPC	Autauga, Barbour, Bibb, Blount, Bullock, Calhoun and 41 more	7 hr
Feb 28, 3:36 PM CST	Mesoscale Discussion	SPC	Autauga, Bibb, Bullock, Calhoun, Chambers, Cherokee and 24 more	84 min
Feb 28, 5:28 AM CST	Mesoscale Discussion	SPC	Alcorn, Attala, Benton, Bolivar, Calhoun, Carroll and 50 more	62 min

Nearby

Mesoscale Discussions in Alabama, 2011 Mesoscale Discussions in Florida, 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.