Alert archive / Florida / Tornado Watches in 2011
Tornado Watch 867
The Storm Prediction Center issued this tornado watch at Oct 18, 2011, 2:21 PM EDT for 14 counties in Florida. It was in force for 8 hr.
The area
The outline as issued.
The facts
- Issued
- Oct 18, 2011, 2:21 PM EDT (18:21 UTC)
- Expired
- Oct 18, 2011, 10:00 PM EDT
- In force
- 8 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 0.5 in
- Strongest gust expected
- 60 kt
Counties Broward County, FL, Charlotte County, FL, Collier County, FL, Glades County, FL, Hendry County, FL, Highlands County, FL, Indian River County, FL, Lee 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), 85 km from the middle of the area, began a volume at 18:24 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
- 40%
- One or more EF2 to EF5 tornadoes
- 20%
- Ten or more severe wind reports
- 20%
- One or more gusts of 65 knots or more
- 10%
- 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
11 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Oct 18, 4:11 PM EDT | Severe Thunderstorm Warning | TBW | Charlotte, Lee | 52 min |
| Oct 18, 7:06 PM EDT | Tornado Warning | MFL | Glades | 28 min |
| Oct 18, 7:34 PM EDT | Tornado Warning | MLB | Martin, Okeechobee, Saint Lucie | 56 min |
| Oct 18, 7:40 PM EDT | Tornado Warning | MFL | Glades | 33 min |
| Oct 18, 8:12 PM EDT | Tornado Warning | MFL | Miami-Dade, Monroe | 33 min |
| Oct 18, 8:27 PM EDT | Tornado Warning | MLB | Okeechobee, Saint Lucie | 48 min |
| Oct 18, 8:45 PM EDT | Tornado Warning | MFL | Miami-Dade | 30 min |
| Oct 18, 9:11 PM EDT | Tornado Warning | MLB | Indian River, Saint Lucie | 34 min |
| Oct 18, 9:14 PM EDT | Severe Thunderstorm Warning | MFL | Palm Beach | 18 min |
| Oct 18, 9:14 PM EDT | Tornado Warning | MFL | Miami-Dade | 31 min |
| Oct 18, 9:44 PM EDT | Tornado Warning | MFL | Broward, Miami-Dade | 31 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, 6.4 hours before the alert went out and 85 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
- 2448 J/kg
- Mixed-layer CIN
- -1 J/kg
- Mixed-layer LCL
- 448 m above ground
- 0-6 km bulk shear
- 26 kt
- 0-1 km storm-relative helicity
- 68 m²/s²
- 0-3 km storm-relative helicity
- 112 m²/s²
- Significant tornado parameter
- 1.0
- Supercell composite
- 5.6
The text
As transmitted, in the capitals the NWS used until 2016.
785
WWUS20 KWNS 181819
SEL7
SPC WW 181819
FLZ000-CWZ000-190200-
URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 867
NWS STORM PREDICTION CENTER NORMAN OK
220 PM EDT TUE OCT 18 2011
THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF
SOUTH FLORIDA
COASTAL WATERS
EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 220 PM UNTIL
1000 PM EDT.
TORNADOES...HAIL TO 0.5 INCH IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.
THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 70 STATUTE
MILES EAST AND WEST OF A LINE FROM 55 MILES NORTHEAST OF FORT
MEYERS FLORIDA TO 50 MILES EAST SOUTHEAST OF MARATHON FLORIDA.
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU7).
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.
DISCUSSION...A LINE OF INTENSE THUNDERSTORMS OFF THE SOUTHWEST COAST
OF FL WILL MOVE EASTWARD AND INLAND THIS AFTERNOON. HIGH THETA-E
VALUES AND MODERATE CAPE...COMBINED WITH SUFFICIENT AND INCREASING
LOW LEVEL WIND FIELDS WILL PROMOTE SUPERCELL STRUCTURES CAPABLE OF
DAMAGING WINDS AND ISOLATED TORNADOES.
AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 0.5 INCH. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
500. MEAN STORM MOTION VECTOR 24030.
...HARTSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Oct 18, 12:15 PM EDT | Mesoscale Discussion | SPC | Broward, Charlotte, Collier, DeSoto, Glades, Hendry and 8 more | 90 min |
| Oct 18, 6:05 PM EDT | Mesoscale Discussion | SPC | Dixie, Jefferson, Leon, Taylor, Wakulla | 85 min |
| Oct 18, 6:41 PM EDT | Mesoscale Discussion | SPC | Charlotte, Collier, DeSoto, Glades, Hardee, Hendry and 3 more | 94 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.