Alert archive / Florida / Mesoscale Discussions in 2021
Mesoscale Discussion 1718
The Storm Prediction Center issued this mesoscale discussion at Sep 8, 2021, 7:17 PM CDT for 6 counties in Florida; Decatur County, Grady County, Georgia. It was in force for 118 min.
The area
The outline as issued.
The facts
- Issued
- Sep 8, 2021, 7:17 PM CDT (00:17 UTC)
- Expired
- Sep 8, 2021, 9:15 PM CDT
- In force
- 118 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
Counties Calhoun County, FL, Gadsden County, FL, Jefferson County, FL, Leon County, FL, Liberty County, FL, Wakulla County, FL, Decatur County, GA, Grady County, GA
The radar
The Tallahassee radar (KTLH), 32 km from the middle of the area, began a volume at 00:17 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 00:00Z, 0.3 hours before the alert went out and 35 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
- 35 J/kg
- Mixed-layer CIN
- -78 J/kg
- Mixed-layer LCL
- 965 m above ground
- 0-6 km bulk shear
- 27 kt
- 0-1 km storm-relative helicity
- 94 m²/s²
- 0-3 km storm-relative helicity
- 129 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.2
The text
As transmitted.
026
ACUS11 KWNS 090018
SWOMCD
SPC MCD 090017
FLZ000-GAZ000-090215-
Mesoscale Discussion 1718
NWS Storm Prediction Center Norman OK
0717 PM CDT Wed Sep 08 2021
Areas affected...portions of the Florida Panhandle
Concerning...Severe potential...Watch unlikely
Valid 090017Z - 090215Z
Probability of Watch Issuance...20 percent
SUMMARY...A brief tornado or damaging gust cannot be ruled out with
one of the stronger, more discrete storms. A WW issuance is not
anticipated given the brief, isolated nature of the severe threat.
DISCUSSION...The center of Tropical Storm Mindy continues to
approach the Florida Panhandle shoreline and is expected to make
landfall within a few hours. However, despite the recent
strengthening of the tropical cyclone, overall vertical shear
profiles still appear relatively mediocre, with 23Z mesoanalysis
depicting only 25-30 kts of effective bulk shear, with the TLH VWP
recently showing 170 m2/s2 0-3 km SRH (with 90 m2/s2 contained
within the 0-1 km layer). Combined with 500-1000 J/kg MLCAPE (and
100-150 J/kg 0-3 km CAPE), a brief tornado or damaging gust may
occur with any robust updraft that can become established and
sustain itself. At the moment, the latest high-resolution guidance
suggests that overall coverage of robust updrafts should be quite
sparse, precluding the need for a watch at this time.
..Squitieri/Grams.. 09/09/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...TAE...
LAT...LON 29648443 29698476 29848507 30038530 30268546 30368556
30548548 30738525 30868489 30958461 30958426 30838391
30498379 30138377 30098385 29888404 29648443SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 8, 9:37 PM CDT | Mesoscale Discussion | SPC | Dixie, Gadsden, Hamilton, Jefferson, Lafayette, Leon and 4 more | 2 hr |
Nearby
Mesoscale Discussions in Florida, 2021Mesoscale Discussions in Georgia, 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.