Alert archive / Alabama / Mesoscale Discussions in 2011

Mesoscale Discussion 15

January 9, 201129 counties in Alabama; 27 counties in Georgia

The Storm Prediction Center issued this mesoscale discussion at Jan 9, 2011, 8:27 PM CST for 29 counties in Alabama; 27 counties in Georgia. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: Jan 9, 2011, 8:27 PM CST (02:27 UTC)
Expired: Jan 10, 2011, 1:00 AM CST
In force: 5 hr
Issued by: the Storm Prediction Center

All 56 counties

Autauga County, AL, Bibb County, AL, Blount County, AL, Calhoun County, AL, Chambers County, AL, Cherokee County, AL, Chilton County, AL, Clay County, AL, Cleburne County, AL, Coosa County, AL, Dallas County, AL, Elmore County, AL, Etowah County, AL, Fayette County, AL, Greene County, AL, Hale County, AL, Jefferson County, AL, Lee County, AL, Macon County, AL, Marengo County, AL, Perry County, AL, Pickens County, AL, Randolph County, AL, Shelby County, AL, St. Clair County, AL, Talladega County, AL, Tallapoosa County, AL, Tuscaloosa County, AL, Walker County, AL, Butts County, GA, Carroll County, GA, Clayton County, GA, Cobb County, GA, Coweta County, GA, DeKalb County, GA, Douglas County, GA, Fayette County, GA, Fulton County, GA, Haralson County, GA, Harris County, GA, Heard County, GA, Henry County, GA, Jasper County, GA, Lamar County, GA, Meriwether County, GA, Monroe County, GA, Muscogee County, GA, Newton County, GA, Paulding County, GA, Pike County, GA, Polk County, GA, Rockdale County, GA, Spalding County, GA, Talbot County, GA, Troup County, GA, Upson County, GA

The nearest sounding before it

Birmingham, AL (KBMX), launched 00:00Z, 2.5 hours before the alert went out and 67 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: 909 m above ground
0-6 km bulk shear: 67 kt
0-1 km storm-relative helicity: 263 m²/s²
0-3 km storm-relative helicity: 531 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.

028 
ACUS11 KWNS 100227
SWOMCD
SPC MCD 100227 
GAZ000-ALZ000-100700-

MESOSCALE DISCUSSION 0015
NWS STORM PREDICTION CENTER NORMAN OK
0827 PM CST SUN JAN 09 2011

AREAS AFFECTED...CNTRL AL...W CNTRL GA

CONCERNING...WINTER MIXED PRECIPITATION 

VALID 100227Z - 100700Z

MIXED PRECIP RATES WILL INCREASE THROUGH THE EVENING ACROSS PORTIONS
OF CNTRL AL INTO W CNTRL GA. PRECIP TYPE IS EXPECTED TO BE FZRA
PRIMARILY S OF I-20...WITH A TRANSITION TO SLEET FURTHER NORTH. 

EARLY EVENING WV IMAGERY SHOWS A COMPACT UPPER LOW CENTERED NEAR THE
ARKLATEX REGION...WITH REGIONAL RADARS INDICATING A BROAD PRECIP
SHIELD AHEAD OF THE SYSTEM ACROSS THE DEEP SOUTH. PRECIP OVER
E-CNTRL AL INTO W-CNTRL GA HAS BEEN SLOW TO ACCUMULATE THUS FAR DUE
TO THE CONTINUED LOW-LEVEL ADVECTION OF COLD DRY AIR INTO THE REGION
BY HIGH PRESSURE OVER THE OHIO VALLEY. HOWEVER...CONSIDERABLE
TOP-DOWN MOISTENING WAS OBSERVED BETWEEN 09/18Z AND 10/00Z SOUNDINGS
AT BMX AND FFC. AS PRECIP CONTINUES TO FALL...FURTHER MOISTENING
WILL ALLOW RATES TO INCREASE...WITH HOURLY LIQUID EQUIVALENT AOA
0.05 IN/HR POSSIBLE BY 03Z-06Z. 

THE PRECIP SHIELD IS BEING DRIVEN BY UPGLIDE OVER THE LOW LEVEL COLD
AIR DOME IN ASSOCIATION WITH A STRONG 55-60 KT LOW-LEVEL JET...AS
SAMPLED BY THE 00Z LIX SOUNDING. WHILE SOME SNOW IS POSSIBLE EARLY
THIS EVENING OVER THE MCD AREA...CONTINUED WAA IN THE 900-700 MB
LAYER SHOULD ALLOW A CHANGEOVER TO SLEET LATER THIS EVENING...WITH
FZRA BECOMING DOMINANT MAINLY SOUTH OF THE I-20 CORRIDOR LATER
TONIGHT AFTER 06Z. 

A MID-LEVEL DRY SLOT /AS NOTED ON WV IMAGERY/ WILL OVERTAKE THE AREA
LATER THIS EVENING...BUT RELATIVELY STEEP LAPSE RATES /6.5-7 C/KM/
ASSOCIATED WITH THIS FEATURE COMBINED WITH CONTINUED STRONG WAA WILL
ALLOW PRECIP OF A MORE CONVECTIVE NATURE TO DEVELOP...WITH LIQUID
EQUIVALENT RATES AOA 0.10 IN/HR POSSIBLE IN HEAVIER SHOWERS.

..DEAN.. 01/10/2011

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

ATTN...WFO...FFC...BMX...HUN...MOB...

LAT...LON   32228782 32618811 32968820 33338824 33698817 33988786
            34078707 34128627 34128547 34088442 33708389 33368350
            33108347 32868377 32608423 32498463 32388528 32258572
            32188651 32198702 32228782

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jan 9, 8:07 PM CST	Mesoscale Discussion	SPC	Colbert, DeKalb, Franklin, Jackson, Lauderdale, Lawrence and 4 more	5 hr
Jan 9, 10:56 PM CST	Mesoscale Discussion	SPC	DeKalb, Jackson	5 hr
Jan 10, 2:06 AM CST	Mesoscale Discussion	SPC	Barbour, Bullock, Chambers, Lee, Macon, Pike and 2 more	6 hr

Nearby

Mesoscale Discussions in Alabama, 2011 Mesoscale Discussions in Georgia, 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.