Alert archive / Alabama / Mesoscale Discussions in 2018

Mesoscale Discussion 930

June 28, 201812 counties in Alabama; 8 counties in Florida; 10 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Jun 28, 2018, 7:01 PM CDT for 12 counties in Alabama; 8 counties in Florida; 10 counties in Mississippi. It was in force for 89 min.

The area

The outline as issued.

The facts

Issued: Jun 28, 2018, 7:01 PM CDT (00:01 UTC)
Expired: Jun 28, 2018, 8:30 PM CDT
In force: 89 min
Issued by: the Storm Prediction Center

All 30 counties

Baldwin County, AL, Choctaw County, AL, Clarke County, AL, Coffee County, AL, Conecuh County, AL, Covington County, AL, Escambia County, AL, Geneva County, AL, Houston County, AL, Mobile County, AL, Monroe County, AL, Washington County, AL, Bay County, FL, Escambia County, FL, Holmes County, FL, Jackson County, FL, Okaloosa County, FL, Santa Rosa County, FL, Walton County, FL, Washington County, FL, Clarke County, MS, George County, MS, Greene County, MS, Jackson County, MS, Jasper County, MS, Jones County, MS, Lauderdale County, MS, Perry County, MS, Stone County, MS, Wayne County, MS

The radar

The Mobile radar (KMOB), 108 km from the middle of the area, began a volume at 00:02 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, 0.0 hours before the alert went out and 213 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: 1512 m above ground
0-6 km bulk shear: 29 kt
0-1 km storm-relative helicity: -141 m²/s²
0-3 km storm-relative helicity: -70 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

401 
ACUS11 KWNS 290002
SWOMCD
SPC MCD 290001 
FLZ000-ALZ000-MSZ000-290130-

Mesoscale Discussion 0930
NWS Storm Prediction Center Norman OK
0701 PM CDT Thu Jun 28 2018

Areas affected...Southeast Mississippi...southern Alabama...west
Florida Panhandle

Concerning...Severe Thunderstorm Watch 236...

Valid 290001Z - 290130Z

The severe weather threat for Severe Thunderstorm Watch 236
continues.

SUMMARY...Severe threat continues across Severe Thunderstorm Watch
0236. Strong, gusty winds remain the primary concern.

DISCUSSION...A strong surface pressure perturbation is currently
driving a cold pool (located across central Alabama) to the
southwest. Organized convection has been maintained in a line along
the leading edge of the cold pool, prompting a risk for strong to
occasionally damaging wind gusts. Several gusts over 35 knots have
been observed over southern Alabama within the past hour, and
additional gusts remain likely until the convective complex moves
off shore. Until then, a very buoyant low-level airmass remains in
place to promote strong, water-loaded downdrafts along the leading
portion of the line, where damaging winds are most likely to be
observed.

..Squitieri/Gleason/Edwards.. 06/29/2018

...Please see www.spc.noaa.gov for graphic product...

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

LAT...LON   31348918 31898926 32658893 32698848 32458839 32228824
            31958776 31768732 31578664 31398590 31308532 30968509
            30648510 30208537 29948586 30118716 30358853 30688912
            31348918

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 28, 8:39 PM CDT	Mesoscale Discussion	SPC	Colbert, Lauderdale	96 min
Jun 28, 11:00 PM CDT	Mesoscale Discussion	SPC	Alcorn, Benton, DeSoto, Marshall, Tippah	90 min

Nearby

Mesoscale Discussions in Alabama, 2018 Mesoscale Discussions in Mississippi, 2018 Mesoscale Discussions in Florida, 2018 Every mesoscale discussion in 2018

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.