Alert archive / Florida / Mesoscale Discussions in 2021
Mesoscale Discussion 1538
The Storm Prediction Center issued this mesoscale discussion at Aug 16, 2021, 6:26 PM CDT for Henry County, Houston County, Alabama; 12 counties in Florida; 11 counties in Georgia. It was in force for 64 min.
The area
The outline as issued.
The facts
- Issued
- Aug 16, 2021, 6:26 PM CDT (23:26 UTC)
- Expired
- Aug 16, 2021, 7:30 PM CDT
- In force
- 64 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 441
All 25 counties
Henry County, AL, Houston County, AL, Bay County, FL, Calhoun County, FL, Franklin County, FL, Gadsden County, FL, Gulf County, FL, Jackson County, FL, Jefferson County, FL, Leon County, FL, Liberty County, FL, Madison County, FL, Taylor County, FL, Wakulla County, FL, Baker County, GA, Brooks County, GA, Colquitt County, GA, Cook County, GA, Decatur County, GA, Early County, GA, Grady County, GA, Miller County, GA, Mitchell County, GA, Seminole County, GA, Thomas County, GA
The radar
The Tallahassee radar (KTLH), 34 km from the middle of the area, began a volume at 23:24 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.
The nearest sounding before it
Tallahassee Rgnl, FL (KTLH), launched 12:00Z, 11.4 hours before the alert went out and 37 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
- 368 J/kg
- Mixed-layer CIN
- -22 J/kg
- Mixed-layer LCL
- 754 m above ground
- 0-6 km bulk shear
- 13 kt
- 0-1 km storm-relative helicity
- 40 m²/s²
- 0-3 km storm-relative helicity
- 30 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
970 ACUS11 KWNS 162326 SWOMCD SPC MCD 162326 FLZ000-GAZ000-ALZ000-170030- Mesoscale Discussion 1538 NWS Storm Prediction Center Norman OK 0626 PM CDT Mon Aug 16 2021 Areas affected...Tropical Storm Fred Concerning...Tornado Watch 441... Valid 162326Z - 170030Z The severe weather threat for Tornado Watch 441 continues. SUMMARY...Some low tornado potential remains with Tropical Storm Fred; however, a new tornado watch may not be warranted. DISCUSSION...Tropical Storm Fred has moved inland with the center of circulation northeast of Panama City. Boundary-layer air mass is not particularly buoyant ahead of Fred as surface temperatures are mostly in the mid-upper 70s across ww441. With poor instability, strong circulations have been limited, though several long-lived, shallow, rotating showers persist, especially from western Taylor-Leon-Decatur County corridor. In the absence of steeper low-level lapse rates, any boundary-layer cooling will likely prove detrimental toward updraft intensity. Will continue to monitor downstream regions for possible new tornado watch, however it's not clear at this time a new watch is warranted. ..Darrow.. 08/16/2021 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...TAE... LAT...LON 29528554 31558553 31398333 29378333 29528554
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 16, 7:33 AM CDT | Tornado Watch | SPC | Houston | 13 hr |
| Aug 16, 5:26 AM CDT | Mesoscale Discussion | SPC | Franklin | 3 hr |
| Aug 16, 9:20 AM CDT | Mesoscale Discussion | SPC | Franklin, Wakulla | 115 min |
| Aug 16, 11:36 AM CDT | Mesoscale Discussion | SPC | Franklin, Taylor, Wakulla | 114 min |
| Aug 16, 2:55 PM CDT | Mesoscale Discussion | SPC | Dixie, Gilchrist, Jefferson, Lafayette, Levy, Taylor | 2 hr |
Nearby
Mesoscale Discussions in Florida, 2021Mesoscale Discussions in Georgia, 2021Mesoscale Discussions in Alabama, 2021Every mesoscale discussion in 2021
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.