Alert archive / Florida / Mesoscale Discussions in 2021

Mesoscale Discussion 369

April 11, 20214 counties in Florida

The Storm Prediction Center issued this mesoscale discussion at Apr 11, 2021, 4:12 PM EDT for 4 counties in Florida. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Apr 11, 2021, 4:12 PM EDT (20:12 UTC)
Expired: Apr 11, 2021, 6:15 PM EDT
In force: 2 hr
Issued by: the Storm Prediction Center
Concerning: Severe thunderstorm watch 92

Counties Broward County, FL, Collier County, FL, Hendry County, FL, Lee County, FL

The radar

The Miami radar (KAMX), 107 km from the middle of the area, began a volume at 20:12 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

Miami, FL (KMFL), launched 12:00Z, 8.2 hours before the alert went out and 104 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: 1240 J/kg
Mixed-layer CIN: -44 J/kg
Mixed-layer LCL: 856 m above ground
0-6 km bulk shear: 33 kt
0-1 km storm-relative helicity: 100 m²/s²
0-3 km storm-relative helicity: 132 m²/s²
Significant tornado parameter: 0.4
Supercell composite: 2.8

Open this sounding in Storm Lab

The text

As transmitted.

357 
ACUS11 KWNS 112012
SWOMCD
SPC MCD 112012 
FLZ000-112215-

Mesoscale Discussion 0369
NWS Storm Prediction Center Norman OK
0312 PM CDT Sun Apr 11 2021

Areas affected...southern Florida

Concerning...Severe Thunderstorm Watch 92...

Valid 112012Z - 112215Z

The severe weather threat for Severe Thunderstorm Watch 92
continues.

SUMMARY...Severe risk has decreased, but a locally damaging gust or
two remain possible over the next 1 to 2 hours.

DISCUSSION...Latest radar loop shows outflow continuing to move
steadily southward across southern Florida, with a decided
anafrontal nature to this boundary having evolved.  It appears that
this trend will continue, with most new storm development occurring
on the boundary and then becoming undercut/slightly elevated.  As
such, severe threat has diminished over the past hour or so.  Still,
gusty winds will accompany passage of the outflow, and a couple of
stronger gusts -- capable of minor damage -- remain possible this
afternoon.

..Goss.. 04/11/2021

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

ATTN...WFO...MFL...TBW...

LAT...LON   26368250 26548232 26668121 26478028 26497972 25887978
            25618066 25808199 26368250

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 11, 5:27 AM EDT	Mesoscale Discussion	SPC	Alachua, Bradford, Citrus, Clay, Dixie, Flagler and 14 more	3 hr
Apr 11, 8:15 AM EDT	Severe Thunderstorm Watch	SPC	Alachua, Brevard, Citrus, DeSoto, Dixie, Flagler and 23 more	8 hr
Apr 11, 10:54 AM EDT	Mesoscale Discussion	SPC	Brevard, Citrus, Hernando, Hillsborough, Lake, Manatee and 9 more	2 hr
Apr 11, 12:08 PM EDT	Mesoscale Discussion	SPC	Brevard, Hillsborough, Manatee, Orange, Osceola, Polk and 1 more	2 hr
Apr 11, 1:24 PM EDT	Mesoscale Discussion	SPC	Broward, Charlotte, Collier, DeSoto, Glades, Hardee and 11 more	2 hr
Apr 11, 2:03 PM EDT	Severe Thunderstorm Watch	SPC	Broward, Charlotte, Collier, Glades, Hendry, Lee and 3 more	6 hr

Nearby

Mesoscale Discussions in Florida, 2021 Every mesoscale discussion in 2021

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.