Alert archive / Florida / Severe Thunderstorm Watches in 2015
Severe Thunderstorm Watch 87
The Storm Prediction Center issued this severe thunderstorm watch at Apr 20, 2015, 1:03 PM EDT for 13 counties in Florida. It was in force for 6 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 20, 2015, 1:03 PM EDT (17:03 UTC)
- Expired
- Apr 20, 2015, 6:51 PM EDT
- In force
- 6 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1.5 in
- Strongest gust expected
- 60 kt
Counties Brevard County, FL, Broward County, FL, Indian River County, FL, Lake County, FL, Martin County, FL, Miami-Dade County, FL, Okeechobee County, FL, Orange County, FL, Osceola County, FL, Palm Beach County, FL, Saint Lucie County, FL, Seminole County, FL, Volusia County, FL
The radar
The Melbourne radar (KMLB), 46 km from the middle of the area, began a volume at 17:02 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
- 10%
- Ten or more severe hail reports
- 40%
- One or more hailstones of 2 inches or more
- 10%
- Six or more combined severe hail and wind reports
- 70%
Warnings issued inside it
4 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 20, 1:06 PM EDT | Severe Thunderstorm Warning | MLB | Okeechobee, Saint Lucie | 39 min |
| Apr 20, 1:33 PM EDT | Tornado Warning | MFL | Miami-Dade | 27 min |
| Apr 20, 3:06 PM EDT | Severe Thunderstorm Warning | MLB | Brevard | 39 min |
| Apr 20, 3:10 PM EDT | Severe Thunderstorm Warning | MLB | Lake, Orange, Seminole | 41 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
Cape Canaveral, FL (KXMR), launched 12:00Z, 5.1 hours before the alert went out and 86 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
- 841 J/kg
- Mixed-layer CIN
- -37 J/kg
- Mixed-layer LCL
- 1041 m above ground
- 0-6 km bulk shear
- 51 kt
- 0-1 km storm-relative helicity
- 16 m²/s²
- 0-3 km storm-relative helicity
- 91 m²/s²
- Significant tornado parameter
- 0.2
- Supercell composite
- 2.2
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 20, 8:35 AM EDT | Mesoscale Discussion | SPC | Alachua, Baker, Bay, Bradford, Calhoun, Columbia and 16 more | 2 hr |
| Apr 20, 11:04 AM EDT | Severe Thunderstorm Watch | SPC | Alachua, Baker, Bradford, Citrus, Clay, Columbia and 22 more | 8 hr |
| Apr 20, 12:13 PM EDT | Mesoscale Discussion | SPC | Brevard, Broward, Indian River, Lake, Martin, Okeechobee and 7 more | 2 hr |
| Apr 20, 2:44 PM EDT | Mesoscale Discussion | SPC | Alachua, Bradford, Citrus, Clay, Duval, Flagler and 12 more | 91 min |
| Apr 20, 4:29 PM EDT | Mesoscale Discussion | SPC | Brevard, Broward, Indian River, Lake, Martin, Miami-Dade and 7 more | 2 hr |
| Apr 20, 5:24 PM EDT | Mesoscale Discussion | SPC | Broward, Hillsborough, Indian River, Manatee, Martin, Okeechobee and 4 more | 96 min |
Nearby
Severe Thunderstorm Watches in Florida, 2015Every severe thunderstorm watch in 2015
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.