Alert archive / Alabama / Mesoscale Discussions in 2018

Mesoscale Discussion 261

April 14, 20184 states

The Storm Prediction Center issued this mesoscale discussion at Apr 14, 2018, 9:27 PM CDT for 4 states. It was in force for 93 min.

The area

The outline as issued.

The facts

Issued: Apr 14, 2018, 9:27 PM CDT (02:27 UTC)
Expired: Apr 14, 2018, 11:00 PM CDT
In force: 93 min
Issued by: the Storm Prediction Center

All 26 counties

Baldwin County, AL, Butler County, AL, Clarke County, AL, Conecuh County, AL, Covington County, AL, Crenshaw County, AL, Dallas County, AL, Escambia County, AL, Lowndes County, AL, Marengo County, AL, Mobile County, AL, Monroe County, AL, Montgomery County, AL, Pike County, AL, Washington County, AL, Wilcox County, AL, Escambia County, FL, Santa Rosa County, FL, Jefferson Parish, LA, Plaquemines Parish, LA, Saint Bernard Parish, LA, George County, MS, Greene County, MS, Harrison County, MS, Jackson County, MS, Stone County, MS

The radar

The Mobile radar (KMOB), 78 km from the middle of the area, began a volume at 02:28 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

Slidell Radar S, LA (KSIL), launched 00:00Z, 2.5 hours before the alert went out and 220 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: 859 m above ground
0-6 km bulk shear: 59 kt
0-1 km storm-relative helicity: -253 m²/s²
0-3 km storm-relative helicity: -353 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

766 
ACUS11 KWNS 150227
SWOMCD
SPC MCD 150227 
ALZ000-FLZ000-MSZ000-LAZ000-150400-

Mesoscale Discussion 0261
NWS Storm Prediction Center Norman OK
0927 PM CDT Sat Apr 14 2018

Areas affected...Southern AL...Far Western FL Peninsula

Concerning...Tornado Watch 49...

Valid 150227Z - 150400Z

The severe weather threat for Tornado Watch 49 continues.

SUMMARY...Threat for damaging wind gusts and brief tornadoes
continues across Tornado Watch 49.

DISCUSSION...An increase in eastward progression has been noted
within the convective line over the past hour or so. Some modest
intensification has been noted as well with the overall convective
structure of the line improving gradually. Surface winds ahead of
the line have moderately strengthened with several surface
observations recently reporting southeasterly gusts over 20 kt.
Recent mesoanalysis as well as regional VAD data (from EVX, EOX and
MXX) show low-level shear and helicity remain favorable for damaging
wind gusts and embedded tornadoes. Downstream areas will be
monitored for possible watch issuance later this evening.

..Mosier.. 04/15/2018

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

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

LAT...LON   32058811 32668744 32448621 31798571 29998726 29148824
            29339032 32058811

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 14, 10:58 PM CDT	Tornado Watch	SPC	Coffee, Dale, Geneva, Henry, Houston	8 hr
Apr 15, 1:45 AM CDT	Mesoscale Discussion	SPC	Coffee, Dale, Geneva, Henry, Houston	2 hr
Apr 15, 5:42 AM CDT	Mesoscale Discussion	SPC	Bay, Calhoun, Gulf, Jackson	93 min
Apr 15, 8:34 AM CDT	Mesoscale Discussion	SPC	Alachua, Baker, Bradford, Columbia, Gilchrist, Hamilton and 4 more	86 min
Apr 15, 9:12 AM CDT	Tornado Watch	SPC	Alachua, Baker, Bradford, Citrus, Clay, Columbia and 22 more	8 hr
Apr 15, 11:18 AM CDT	Mesoscale Discussion	SPC	Hardee, Hillsborough, Manatee, Polk	57 min
Apr 15, 1:30 PM CDT	Mesoscale Discussion	SPC	Clay, Duval, Lake, Manatee, Polk, Putnam and 1 more	90 min
Apr 15, 3:42 PM CDT	Mesoscale Discussion	SPC	Broward, Collier, DeSoto, Glades, Hardee, Hendry and 4 more	63 min

Nearby

Mesoscale Discussions in Alabama, 2018 Mesoscale Discussions in Mississippi, 2018 Mesoscale Discussions in Louisiana, 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.