Alert archive / Alabama / Mesoscale Discussions in 2012

Mesoscale Discussion 237

March 8, 20128 counties in Alabama; Lowndes County, Oktibbeha County, Mississippi

The Storm Prediction Center issued this mesoscale discussion at Mar 8, 2012, 7:12 PM CST for 8 counties in Alabama; Lowndes County, Oktibbeha County, Mississippi. It was in force for 93 min.

The area

The outline as issued.

The facts

Issued: Mar 8, 2012, 7:12 PM CST (01:12 UTC)
Expired: Mar 8, 2012, 8:45 PM CST
In force: 93 min
Issued by: the Storm Prediction Center

Counties Cullman County, AL, Fayette County, AL, Jefferson County, AL, Lamar County, AL, Pickens County, AL, Tuscaloosa County, AL, Walker County, AL, Winston County, AL, Lowndes County, MS, Oktibbeha County, MS

The radar

The Columbus AFB radar (KGWX), 72 km from the middle of the area, began a volume at 01:11 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 00:00Z, 1.2 hours before the alert went out and 93 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: 264 J/kg
Mixed-layer CIN: -6 J/kg
Mixed-layer LCL: 1136 m above ground
0-6 km bulk shear: 46 kt
0-1 km storm-relative helicity: 105 m²/s²
0-3 km storm-relative helicity: 213 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 0.7

Open this sounding in Storm Lab

The text

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

623 
ACUS11 KWNS 090112
SWOMCD
SPC MCD 090112 
ALZ000-MSZ000-090245-

MESOSCALE DISCUSSION 0237
NWS STORM PREDICTION CENTER NORMAN OK
0712 PM CST THU MAR 08 2012

AREAS AFFECTED...PARTS OF NERN MS/NWRN AL

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 090112Z - 090245Z

LIMITED THREAT FOR DAMAGING WINDS -- BOTH IN TERMS OF MAGNITUDE AND
OF SPATIAL EXTENT -- IS ONGOING ACROSS A SMALL PORTION OF NWRN AL
AND ADJACENT NERN MS ATTM.  WW IS NOT ANTICIPATED.

A STRONGER/MORE ACTIVE PORTION OF THE LARGER-SCALE CONVECTIVE LINE
STRETCHING ENE-WSW ALONG THE ADVANCING COLD FRONT HAS EVOLVED OVER
THE PAST 1-2 HOURS...WITH OCCASIONAL/SPORADIC REPORTS OF WIND DAMAGE
DURING THIS TIME.  A SOMEWHAT STRONGER COLD POOL ASSOCIATED WITH
THIS ENHANCED CONVECTIVE SEGMENT HAS EVOLVED...WHICH SHOULD ALLOW
SOME CONTINUATION OF THE STRONGER STORMS AS THEY CONTINUE TO SHIFT
EWD OUT OF MS INTO NWRN AL.

MODEST DEEP-LAYER SHEAR AND 500 TO 1000 J/KG MIXED LAYER CAPE --
REVEALED IN EVENING RAOBS -- HAS BEEN SUPPORTING THE OBSERVED UPTICK
IN CONVECTIVE INTENSITY...WITH SURFACE DEWPOINTS ACROSS NRN MS AND
INTO FAR NWRN AL IN THE LOW 60S AIDING THE AVAILABLE CAPE.  FARTHER
E INTO AL HOWEVER...DEWPOINTS 3-4 DEGREES LOWER ARE YIELDING MORE
LIMITED INSTABILITY...AND ALSO THE LIKELIHOOD FOR GREATER DIURNAL
COOLING OVER THE NEXT COUPLE OF HOURS.  THUS -- AS THERMODYNAMIC
ENVIRONMENT BECOMES INCREASINGLY LESS SUPPORTIVE OF VIGOROUS
CONVECTION...EXPECT ONGOING/LIMITED WIND THREAT TO DIMINISH SLOWLY
OVER THE NEXT 1-2 HOURS -- MITIGATING THE NEED FOR WW ISSUANCE.

..GOSS.. 03/09/2012

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

ATTN...WFO...BMX...HUN...MEG...JAN...

LAT...LON   33168807 33488914 34258740 34258692 33818656 33278720
            33168807

Nearby

Mesoscale Discussions in Alabama, 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.