Alert archive / Florida / Severe Thunderstorm Watches in 2018
Severe Thunderstorm Watch 440
The Storm Prediction Center issued this severe thunderstorm watch at Dec 20, 2018, 2:15 PM EST for 12 counties in Florida. It was in force for 6 hr.
The area
The outline as issued.
The facts
- Issued
- Dec 20, 2018, 2:15 PM EST (19:15 UTC)
- Expired
- Dec 20, 2018, 8:17 PM EST
- In force
- 6 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 0.5 in
- Strongest gust expected
- 60 kt
Counties Brevard County, FL, Broward County, FL, Collier County, FL, Glades County, FL, Hendry County, FL, Indian River County, FL, Martin County, FL, Miami-Dade County, FL, Monroe County, FL, Okeechobee County, FL, Palm Beach County, FL, Saint Lucie County, FL
The radar
The Miami radar (KAMX), 64 km from the middle of the area, began a volume at 19:14 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
- 20%
- One or more EF2 to EF5 tornadoes
- 5%
- Ten or more severe wind reports
- 50%
- One or more gusts of 65 knots or more
- 20%
- Ten or more severe hail reports
- 5%
- One or more hailstones of 2 inches or more
- 5%
- Six or more combined severe hail and wind reports
- 60%
Warnings issued inside it
2 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 20, 2:25 PM EST | Severe Thunderstorm Warning | MLB | Brevard | 27 min |
| Dec 20, 2:46 PM EST | Tornado Warning | MFL | Collier | 29 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, 7.3 hours before the alert went out and 71 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
- 343 J/kg
- Mixed-layer CIN
- -14 J/kg
- Mixed-layer LCL
- 787 m above ground
- 0-6 km bulk shear
- 55 kt
- 0-1 km storm-relative helicity
- 262 m²/s²
- 0-3 km storm-relative helicity
- 271 m²/s²
- Significant tornado parameter
- 0.6
- Supercell composite
- 4.1
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 20, 6:28 AM EST | Mesoscale Discussion | SPC | Manatee, Sarasota | 62 min |
| Dec 20, 7:38 AM EST | Mesoscale Discussion | SPC | Brevard, Charlotte, Collier, DeSoto, Glades, Hardee and 11 more | 97 min |
| Dec 20, 7:55 AM EST | Tornado Watch | SPC | Brevard, Charlotte, Collier, DeSoto, Glades, Hardee and 15 more | 7 hr |
| Dec 20, 10:49 AM EST | Mesoscale Discussion | SPC | Brevard, Charlotte, DeSoto, Glades, Hardee, Hendry and 11 more | 116 min |
| Dec 20, 1:41 PM EST | Mesoscale Discussion | SPC | Brevard, Collier, Glades, Hendry, Highlands, Indian River and 7 more | 2 hr |
| Dec 20, 5:55 PM EST | Mesoscale Discussion | SPC | Broward, Miami-Dade | 2 hr |
Nearby
Severe Thunderstorm Watches in Florida, 2018Every severe thunderstorm watch 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.