Alert archive / Alabama / Mesoscale Discussions in 2009

Mesoscale Discussion 721

May 5, 200919 counties in Alabama

The Storm Prediction Center issued this mesoscale discussion at May 5, 2009, 11:45 PM CDT for 19 counties in Alabama. It was in force for 90 min.

The area

The outline as issued.

The facts

Issued: May 5, 2009, 11:45 PM CDT (04:45 UTC)
Expired: May 6, 2009, 1:15 AM CDT
In force: 90 min
Issued by: the Storm Prediction Center

Counties Blount County, AL, Calhoun County, AL, Colbert County, AL, Cullman County, AL, Etowah County, AL, Fayette County, AL, Franklin County, AL, Jefferson County, AL, Lamar County, AL, Lawrence County, AL, Marion County, AL, Marshall County, AL, Morgan County, AL, Shelby County, AL, St. Clair County, AL, Talladega County, AL, Tuscaloosa County, AL, Walker County, AL, Winston County, AL

The radar

The Birmingham radar (KBMX), 81 km from the middle of the area, began a volume at 04:45 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, 4.8 hours before the alert went out and 80 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: 159 J/kg
Mixed-layer CIN: -23 J/kg
Mixed-layer LCL: 1106 m above ground
0-6 km bulk shear: 29 kt
0-1 km storm-relative helicity: 58 m²/s²
0-3 km storm-relative helicity: 174 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.

000 
ACUS11 KWNS 060445
SWOMCD
SPC MCD 060445 
ALZ000-060615-

MESOSCALE DISCUSSION 0721
NWS STORM PREDICTION CENTER NORMAN OK
1145 PM CDT TUE MAY 05 2009

AREAS AFFECTED...NRN/CNTRL AL

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 060445Z - 060615Z

PROFILERS/VWPS INDICATE A 50+ KT MID-LVL JET ASSOCD WITH THE MCV
FEATURE OVER AR...BEGINNING TO NOSE EWD THROUGH SRN AR AND NRN MS.
EXIT REGION OF THIS JETLET WAS SUPPORTING TSTM CLUSTERS OVER A VERY
LARGE REGION OF THE MID-SOUTH LATE THIS EVENING.  LONG-TERM RADAR
LOOPS ALSO SUGGEST THAT THE STORMS OVER NRN MS ARE REMNANTS OF THE
ORGANIZED FORWARD PROPAGATING SYSTEM THAT AFFECTED SRN AR TUESDAY
AFTN AND ALSO LIKELY CONTAINS A WEAK MCV.  

PRIND THAT TSTMS WILL DEVELOP AND/OR MOVE EWD INTO PARTS OF
NRN/CNTRL AL THROUGH 09Z.  CURRENT OBJECTIVE ANALYSIS PLACES AN
INSTABILITY GRADIENT ACROSS CNTRL MS...BUT TRENDS HAVE BEEN FOR
DESTABILIZATION ALOFT NEWD WITH TIME WITH MUCAPE EXPECTED TO RANGE
FROM 500-1500 J/KG LATER TONIGHT.  STEEPENING OF THE LAPSE RATES AND
STRENGTHENING OF THE SHEAR WITHIN THE BUOYANT LAYER WILL LIKELY
YIELD AT LEAST ISOLD STG/SVR STORMS CAPABLE OF LARGE HAIL AND
PERHAPS GUSTY WINDS.

REGION WILL CONTINUE TO BE MONITORED FOR A POSSIBLE SVR TSTM WATCH.

..RACY.. 05/06/2009

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

ATTN...WFO...BMX...HUN...

LAT...LON   34898807 34338576 33758558 33328581 33138641 33208747
            33628823 34898807

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 6, 1:27 AM CDT	Mesoscale Discussion	SPC	Blount, Cullman, Fayette, Franklin, Jefferson, Lamar and 4 more	3 hr
May 6, 3:05 AM CDT	Mesoscale Discussion	SPC	Fayette, Jefferson, Lamar, Marion, Pickens, Tuscaloosa and 1 more	115 min
May 6, 4:03 AM CDT	Severe Thunderstorm Watch	SPC	Bibb, Blount, Calhoun, Cherokee, Clay, Cleburne and 27 more	6 hr
May 6, 6:58 AM CDT	Mesoscale Discussion	SPC	Greene, Pickens, Sumter	3 hr
May 6, 7:22 AM CDT	Mesoscale Discussion	SPC	Bibb, Blount, Calhoun, Cherokee, Chilton, Clay and 28 more	83 min
May 6, 9:04 AM CDT	Mesoscale Discussion	SPC	Autauga, Bibb, Blount, Bullock, Butler, Calhoun and 27 more	56 min
May 6, 9:27 AM CDT	Tornado Watch	SPC	Autauga, Barbour, Bibb, Blount, Bullock, Calhoun and 31 more	9 hr
May 6, 12:37 PM CDT	Severe Thunderstorm Watch	SPC	Butler, Choctaw, Clarke, Conecuh, Covington, Crenshaw and 4 more	6 hr
May 6, 1:57 PM CDT	Mesoscale Discussion	SPC	Bullock, Russell	93 min
May 6, 4:47 PM CDT	Mesoscale Discussion	SPC	Dale, Geneva, Henry	58 min

Nearby

Mesoscale Discussions in Alabama, 2009 Every mesoscale discussion in 2009

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.