Alert archive / Florida / Mesoscale Discussions in 2021
Mesoscale Discussion 38
The Storm Prediction Center issued this mesoscale discussion at Jan 27, 2021, 7:50 AM CST for 4 counties in Florida; 4 counties in Georgia. It was in force for 115 min.
The area
The outline as issued.
The facts
- Issued
- Jan 27, 2021, 7:50 AM CST (13:50 UTC)
- Expired
- Jan 27, 2021, 9:45 AM CST
- In force
- 115 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
Counties Bay County, FL, Calhoun County, FL, Gadsden County, FL, Jackson County, FL, Decatur County, GA, Grady County, GA, Seminole County, GA, Thomas County, GA
The radar
The Tallahassee radar (KTLH), 52 km from the middle of the area, began a volume at 13:51 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, 1.8 hours before the alert went out and 55 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
- 128 J/kg
- Mixed-layer CIN
- -29 J/kg
- Mixed-layer LCL
- 548 m above ground
- 0-6 km bulk shear
- 56 kt
- 0-1 km storm-relative helicity
- 183 m²/s²
- 0-3 km storm-relative helicity
- 308 m²/s²
- Significant tornado parameter
- 0.2
- Supercell composite
- 1.6
The text
As transmitted.
046
ACUS11 KWNS 271350
SWOMCD
SPC MCD 271350
GAZ000-FLZ000-271545-
Mesoscale Discussion 0038
NWS Storm Prediction Center Norman OK
0750 AM CST Wed Jan 27 2021
Areas affected...Portions of the FL Panhandle and far southwestern
GA
Concerning...Severe potential...Watch unlikely
Valid 271350Z - 271545Z
Probability of Watch Issuance...20 percent
SUMMARY...An isolated severe threat may exist this morning, with
strong/gusty winds and perhaps a brief tornado possible. Watch
issuance is unlikely.
DISCUSSION...A low-topped supercell over the central FL Panhandle
has shown signs of low-level rotation over the 30 minutes or so.
Modest low-level warm advection is aiding convective development
across this area along/south of a surface boundary, which is draped
generally east-west across the FL Panhandle and into southern GA.
Although the latest VWP from KTLH shows winds generally veered to
southwesterly in the 0-1 km layer, there is strengthening with
height to around 30 kt at 1 km. Low-level shear may also be modestly
enhanced near the surface boundary, where 100-150 m2/s2 of effective
SRH is present per mesoanalysis estimates. Given the low-level
rotation already observed in the supercell along the boundary, a
brief tornado cannot be ruled out. Isolated strong/gusty winds may
also occur. The 12Z sounding from TLH showed poor low-level lapse
rates and limited boundary-layer instability. This should tend to
limit the overall severe threat, and a watch is not currently
expected.
..Gleason/Edwards.. 01/27/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...TAE...
LAT...LON 30448582 30948511 31158450 31208394 30978370 30628400
30448441 30218501 30128558 30448582SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jan 27, 10:16 AM CST | Mesoscale Discussion | SPC | Franklin, Gadsden, Gulf, Jefferson, Leon, Liberty and 2 more | 119 min |
| Jan 27, 1:04 PM CST | Mesoscale Discussion | SPC | Baker, Columbia, Duval, Hamilton, Nassau | 116 min |
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.