Alert archive / Florida / Severe Thunderstorm Watches in 2011
Severe Thunderstorm Watch 254
The Storm Prediction Center issued this severe thunderstorm watch at Apr 28, 2011, 9:47 AM EDT for 19 counties in Florida; 14 counties in Georgia. It was in force for 9 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 28, 2011, 9:47 AM EDT (13:47 UTC)
- Expired
- Apr 28, 2011, 7:00 PM EDT
- In force
- 9 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 33 counties
Alachua County, FL, Baker County, FL, Bradford County, FL, Clay County, FL, Columbia County, FL, Dixie County, FL, Duval County, FL, Flagler County, FL, Gilchrist County, FL, Hamilton County, FL, Lafayette County, FL, Madison County, FL, Marion County, FL, Nassau County, FL, Putnam County, FL, Saint Johns County, FL, Suwannee County, FL, Taylor County, FL, Union County, FL, Appling County, GA, Atkinson County, GA, Bacon County, GA, Brantley County, GA, Camden County, GA, Charlton County, GA, Clinch County, GA, Echols County, GA, Glynn County, GA, Lanier County, GA, Lowndes County, GA, Pierce County, GA, Ware County, GA, Wayne County, GA
The radar
The Jacksonville radar (KJAX), 70 km from the middle of the area, began a volume at 13:48 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
- 30%
- One or more gusts of 65 knots or more
- 30%
- Ten or more severe hail reports
- 30%
- One or more hailstones of 2 inches or more
- 20%
- Six or more combined severe hail and wind reports
- 70%
Warnings issued inside it
22 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 28, 10:14 AM EDT | Severe Thunderstorm Warning | TAE | Brooks, Lanier, Lowndes | 61 min |
| Apr 28, 10:41 AM EDT | Severe Thunderstorm Warning | TAE | Jefferson, Madison | 49 min |
| Apr 28, 10:46 AM EDT | Severe Thunderstorm Warning | TAE | Jefferson, Taylor | 44 min |
| Apr 28, 11:13 AM EDT | Severe Thunderstorm Warning | TAE | Lanier, Lowndes | 32 min |
| Apr 28, 11:21 AM EDT | Severe Thunderstorm Warning | JAX | Atkinson, Bacon, Clinch, Coffee, Echols, Ware | 54 min |
| Apr 28, 11:58 AM EDT | Severe Thunderstorm Warning | JAX | Hamilton | 32 min |
| Apr 28, 12:11 PM EDT | Severe Thunderstorm Warning | JAX | Clinch, Echols | 20 min |
| Apr 28, 12:30 PM EDT | Severe Thunderstorm Warning | JAX | Columbia, Hamilton | 30 min |
| Apr 28, 12:39 PM EDT | Severe Thunderstorm Warning | TAE | Madison | 21 min |
| Apr 28, 12:40 PM EDT | Severe Thunderstorm Warning | JAX | Hamilton, Suwannee | 21 min |
| Apr 28, 12:45 PM EDT | Tornado Warning | JAX | Columbia, Hamilton | 30 min |
| Apr 28, 12:46 PM EDT | Severe Thunderstorm Warning | TAE | Lafayette, Taylor | 44 min |
| Apr 28, 12:54 PM EDT | Severe Thunderstorm Warning | JAX | Hamilton, Suwannee | 51 min |
| Apr 28, 12:56 PM EDT | Tornado Warning | TAE | Lafayette | 34 min |
| Apr 28, 1:14 PM EDT | Severe Thunderstorm Warning | JAX | Columbia, Hamilton | 46 min |
| Apr 28, 1:29 PM EDT | Severe Thunderstorm Warning | TAE | Lafayette | 31 min |
| Apr 28, 1:42 PM EDT | Severe Thunderstorm Warning | JAX | Hamilton, Suwannee | 63 min |
| Apr 28, 3:15 PM EDT | Severe Thunderstorm Warning | JAX | Flagler, Putnam | 45 min |
| Apr 28, 3:18 PM EDT | Severe Thunderstorm Warning | JAX | Brantley, Camden, Charlton, Glynn, Ware, Wayne | 42 min |
| Apr 28, 3:37 PM EDT | Tornado Warning | JAX | Brantley, Camden, Charlton, Glynn, Ware, Wayne | 23 min |
| Apr 28, 3:56 PM EDT | Tornado Warning | JAX | Brantley, Camden, Glynn | 34 min |
| Apr 28, 4:11 PM EDT | Severe Thunderstorm Warning | JAX | Glynn, Wayne | 19 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
Jacksonville, FL (KJAX), launched 12:00Z, 1.8 hours before the alert went out and 69 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
- 1394 J/kg
- Mixed-layer CIN
- -52 J/kg
- Mixed-layer LCL
- 817 m above ground
- 0-6 km bulk shear
- 21 kt
- 0-1 km storm-relative helicity
- 161 m²/s²
- 0-3 km storm-relative helicity
- 154 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 3.5
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 28, 2:22 AM EDT | Mesoscale Discussion | SPC | Holmes | 83 min |
| Apr 28, 12:19 PM EDT | Mesoscale Discussion | SPC | Alachua, Baker, Bradford, Clay, Columbia, Dixie and 9 more | 56 min |
| Apr 28, 3:34 PM EDT | Mesoscale Discussion | SPC | Brevard, Broward, Charlotte, Collier, DeSoto, Glades and 25 more | 56 min |
| Apr 27, 8:55 PM EDT | Mesoscale Discussion | SPC | Chattooga, Walker | 65 min |
| Apr 28, 12:09 AM EDT | Mesoscale Discussion | SPC | Banks, Barrow, Bartow, Bibb, Butts, Carroll and 65 more | 36 min |
| Apr 28, 12:56 AM EDT | Tornado Watch | SPC | Baldwin, Banks, Barrow, Bibb, Bleckley, Burke and 80 more | 4 hr |
| Apr 28, 3:30 AM EDT | Mesoscale Discussion | SPC | Baldwin, Bibb, Bleckley, Burke, Chattahoochee, Columbia and 30 more | 90 min |
| Apr 28, 4:30 AM EDT | Tornado Watch | SPC | Baldwin, Bibb, Bleckley, Bulloch, Burke, Candler and 37 more | 10 hr |
| Apr 28, 8:05 AM EDT | Mesoscale Discussion | SPC | Burke, Candler, Dodge, Emanuel, Jefferson, Jenkins and 5 more | 85 min |
| Apr 28, 8:48 AM EDT | Tornado Watch | SPC | Bryan, Bulloch, Candler, Chatham, Effingham, Evans and 6 more | 7 hr |
| Apr 28, 11:22 AM EDT | Mesoscale Discussion | SPC | Bulloch, Burke, Candler, Chatham, Effingham, Emanuel and 2 more | 53 min |
Nearby
Severe Thunderstorm Watches in Florida, 2011Severe Thunderstorm Watches in Georgia, 2011Every severe thunderstorm watch in 2011
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.