Alert archive / Florida / Tornado Watches in 2017
Tornado Watch 481
The Storm Prediction Center issued this tornado watch at Sep 9, 2017, 12:09 PM EDT for 9 counties in Florida. It was in force for 12 hr.
The area
The outline as issued.
The facts
- Issued
- Sep 9, 2017, 12:09 PM EDT (16:09 UTC)
- Expired
- Sep 10, 2017, 12:00 AM EDT
- In force
- 12 hr
- Issued by
- the Storm Prediction Center
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), 60 km from the middle of the area, began a volume at 16:11 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.
Warnings issued inside it
16 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 9, 12:22 PM EDT | Tornado Warning | MFL | Collier | 23 min |
| Sep 9, 4:46 PM EDT | Tornado Warning | MFL | Broward | 29 min |
| Sep 9, 4:48 PM EDT | Tornado Warning | MFL | Collier | 27 min |
| Sep 9, 5:34 PM EDT | Tornado Warning | KEY | Monroe | 26 min |
| Sep 9, 5:56 PM EDT | Tornado Warning | KEY | Monroe | 49 min |
| Sep 9, 6:22 PM EDT | Tornado Warning | MFL | Broward, Palm Beach | 38 min |
| Sep 9, 6:30 PM EDT | Tornado Warning | MFL | Broward | 30 min |
| Sep 9, 6:54 PM EDT | Tornado Warning | MFL | Hendry, Palm Beach | 36 min |
| Sep 9, 6:59 PM EDT | Tornado Warning | MFL | Broward | 31 min |
| Sep 9, 7:02 PM EDT | Tornado Warning | MFL | Miami-Dade | 13 min |
| Sep 9, 7:07 PM EDT | Tornado Warning | KEY | Monroe | 23 min |
| Sep 9, 7:12 PM EDT | Tornado Warning | MFL | Palm Beach | 48 min |
| Sep 9, 7:27 PM EDT | Tornado Warning | MFL | Broward | 33 min |
| Sep 9, 7:29 PM EDT | Tornado Warning | MFL | Miami-Dade | 26 min |
| Sep 9, 7:52 PM EDT | Tornado Warning | MFL | Broward, Miami-Dade | 23 min |
| Sep 9, 7:55 PM EDT | Flash Flood Warning | TBW | Lee | 6 hr |
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, 4.2 hours before the alert went out and 42 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
- 1745 J/kg
- Mixed-layer CIN
- -3 J/kg
- Mixed-layer LCL
- 926 m above ground
- 0-6 km bulk shear
- 18 kt
- 0-1 km storm-relative helicity
- 182 m²/s²
- 0-3 km storm-relative helicity
- 212 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
670 WWUS20 KWNS 091606 SEL1 SPC WW 091606 FLZ000-CWZ000-100400- URGENT - IMMEDIATE BROADCAST REQUESTED Tornado Watch Number 481 NWS Storm Prediction Center Norman OK 1210 PM EDT Sat Sep 9 2017 The NWS Storm Prediction Center has issued a * Tornado Watch for portions of southern Florida Coastal Waters * Effective this Saturday from 1210 PM until Midnight EDT. * Primary threats include... A few tornadoes possible Isolated damaging wind gusts to 70 mph possible SUMMARY...As convection within outer bands of approaching Hurricane Irma continues to move eastward across south Florida, risk for tornadoes will gradually increase through this afternoon and evening with embedded/stronger cells. The tornado watch area is approximately along and 95 statute miles east and west of a line from 80 miles northeast of Fort Myers FL to 40 miles southeast of Marathon FL. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU1). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Tornado Watch means conditions are favorable for tornadoes and 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. && AVIATION...Tornadoes and a few severe thunderstorms with hail surface and aloft to 0.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 9045. ...Goss
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 9, 8:48 AM EDT | Mesoscale Discussion | SPC | Broward, Martin, Miami-Dade, Palm Beach | 3 hr |
| Sep 9, 4:12 PM EDT | Mesoscale Discussion | SPC | Broward, Charlotte, Collier, Glades, Hendry, Lee and 3 more | 2 hr |
| Sep 9, 7:25 PM EDT | Mesoscale Discussion | SPC | Brevard, Indian River, Martin, Okeechobee, Osceola, Saint Lucie | 65 min |
Nearby
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.