Alert archive / Florida / Severe Thunderstorm Watches in 2021
Severe Thunderstorm Watch 92
The Storm Prediction Center issued this severe thunderstorm watch at Apr 11, 2021, 2:03 PM EDT for 9 counties in Florida. It was in force for 6 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 11, 2021, 2:03 PM EDT (18:03 UTC)
- Expired
- Apr 11, 2021, 7:45 PM EDT
- In force
- 6 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1 in
- Strongest gust expected
- 60 kt
Counties Broward County, FL, Charlotte County, FL, Collier County, FL, Glades County, FL, Hendry County, FL, Lee County, FL, Miami-Dade County, FL, Monroe County, FL, Palm Beach County, FL
The radar
The Miami radar (KAMX), 93 km from the middle of the area, began a volume at 18:02 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.
What SPC expected
The probabilities SPC published with the watch, for the watch area over its life.
- Two or more tornadoes
- 10%
- One or more EF2 to EF5 tornadoes
- 2%
- Ten or more severe wind reports
- 40%
- One or more gusts of 65 knots or more
- 20%
- Ten or more severe hail reports
- 20%
- One or more hailstones of 2 inches or more
- 10%
- Six or more combined severe hail and wind reports
- 60%
Warnings issued inside it
7 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 11, 2:25 PM EDT | Severe Thunderstorm Warning | MFL | Glades | 35 min |
| Apr 11, 2:39 PM EDT | Severe Thunderstorm Warning | MFL | Palm Beach | 66 min |
| Apr 11, 2:56 PM EDT | Severe Thunderstorm Warning | MFL | Palm Beach | 64 min |
| Apr 11, 4:08 PM EDT | Severe Thunderstorm Warning | TBW | Lee | 17 min |
| Apr 11, 4:18 PM EDT | Severe Thunderstorm Warning | MFL | Broward | 40 min |
| Apr 11, 5:24 PM EDT | Severe Thunderstorm Warning | MFL | Broward, Miami-Dade | 36 min |
| Apr 11, 6:09 PM EDT | Severe Thunderstorm Warning | MFL | Miami-Dade | 36 min |
Discussions around it
SPC mesoscale discussions over the same counties from four hours before the watch to its end.
The nearest sounding before it
Miami, FL (KMFL), launched 12:00Z, 6.1 hours before the alert went out and 76 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.
- 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
The text
As transmitted.
218 WWUS20 KWNS 111759 SEL2 SPC WW 111759 FLZ000-CWZ000-120000- URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 92 NWS Storm Prediction Center Norman OK 200 PM EDT Sun Apr 11 2021 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of South Florida Coastal Waters * Effective this Sunday afternoon and evening from 200 PM until 800 PM EDT. * Primary threats include... Scattered damaging wind gusts to 70 mph possible Isolated large hail events to 1 inch in diameter possible SUMMARY...A band of storms with embedded clusters and bowing segments will continue to develop southeastward across south Florida through the afternoon. The strongest storms will be capable of producing occasional damaging outflow winds and isolated large hail. The severe thunderstorm watch area is approximately along and 80 statute miles east and west of a line from 60 miles northeast of Fort Myers FL to 40 miles south southwest of Miami FL. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU2). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && OTHER WATCH INFORMATION...CONTINUE...WW 91... AVIATION...A few severe thunderstorms with hail surface and aloft to 1 inch. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 29035. ...Thompson
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, 4:12 PM EDT | Mesoscale Discussion | SPC | Broward, Collier, Hendry, Lee | 2 hr |
Nearby
Severe Thunderstorm Watches in Florida, 2021Every severe thunderstorm watch 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.