Alert archive / Florida / Mesoscale Discussions in 2021

Mesoscale Discussion 367

April 11, 20217 counties in Florida

The Storm Prediction Center issued this mesoscale discussion at Apr 11, 2021, 12:08 PM EDT for 7 counties in Florida. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Apr 11, 2021, 12:08 PM EDT (16:08 UTC)
Expired: Apr 11, 2021, 2:15 PM EDT
In force: 2 hr
Issued by: the Storm Prediction Center
Concerning: Severe thunderstorm watch 91

Counties Brevard County, FL, Hillsborough County, FL, Manatee County, FL, Orange County, FL, Osceola County, FL, Polk County, FL, Seminole County, FL

The radar

The Tampa radar (KTBW), 29 km from the middle of the area, began a volume at 16:10 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

Tampa Bay, FL (KTBW), launched 12:00Z, 4.1 hours before the alert went out and 29 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: 1004 J/kg
Mixed-layer CIN: -131 J/kg
Mixed-layer LCL: 1005 m above ground
0-6 km bulk shear: 57 kt
0-1 km storm-relative helicity: 288 m²/s²
0-3 km storm-relative helicity: 296 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.3

Open this sounding in Storm Lab

The text

As transmitted.

320 
ACUS11 KWNS 111609
SWOMCD
SPC MCD 111608 
FLZ000-111815-

Mesoscale Discussion 0367
NWS Storm Prediction Center Norman OK
1108 AM CDT Sun Apr 11 2021

Areas affected...central Florida

Concerning...Severe Thunderstorm Watch 91...

Valid 111608Z - 111815Z

The severe weather threat for Severe Thunderstorm Watch 91
continues.

SUMMARY...Risk for locally damaging winds continues -- and is
shifting gradually southward with time.

DISCUSSION...Latest radar loop shows the initial/small bowing
cluster of storms moving eastward just to the northeast of Tampa
Bay, and is moving eastward at around 50 kt.  This cluster will
affect the Orlando area, bringing gusty winds, in the next 30 to 45
minutes.

Meanwhile, a second small bowing cluster appears to be organizing 
to the west-southwest along this same convective band, and should 
cross the Tampa Bay area and areas just south over the next half
hour to hour.  Here also, gusty winds -- possibly reaching severe
levels locally -- can be expected.

..Goss.. 04/11/2021

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

ATTN...WFO...MLB...TBW...

LAT...LON   27488382 27758342 27888280 28078231 28288216 28558188
            28738098 28288048 27708140 27358260 27488382

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, 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
Apr 11, 4:12 PM EDT	Mesoscale Discussion	SPC	Broward, Collier, Hendry, Lee	2 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.