Alert archive / Florida / Mesoscale Discussions in 2021
Mesoscale Discussion 602
The Storm Prediction Center issued this mesoscale discussion at May 12, 2021, 6:43 AM CDT for Geneva County, Houston County, Alabama; 12 counties in Florida; Seminole County, Georgia. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- May 12, 2021, 6:43 AM CDT (11:43 UTC)
- Expired
- May 12, 2021, 8:45 AM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 40%
Counties Geneva County, AL, Houston County, AL, Bay County, FL, Calhoun County, FL, Franklin County, FL, Gadsden County, FL, Gulf County, FL, Holmes County, FL, Jackson County, FL, Liberty County, FL, Okaloosa County, FL, Wakulla County, FL, Walton County, FL, Washington County, FL, Seminole County, GA
The radar
The Eglin Afb radar (KEVX), 36 km from the middle of the area, began a volume at 11:47 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 watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Tallahassee Rgnl, FL (KTLH), launched 00:00Z, 11.7 hours before the alert went out and 127 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
- 1708 J/kg
- Mixed-layer CIN
- 0 J/kg
- Mixed-layer LCL
- 617 m above ground
- 0-6 km bulk shear
- 23 kt
- 0-1 km storm-relative helicity
- 83 m²/s²
- 0-3 km storm-relative helicity
- 73 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
430
ACUS11 KWNS 121143
SWOMCD
SPC MCD 121143
FLZ000-GAZ000-ALZ000-121345-
Mesoscale Discussion 0602
NWS Storm Prediction Center Norman OK
0643 AM CDT Wed May 12 2021
Areas affected...far southern Alabama into the Florida Panhandle and
a portion of far southwestern Georgia
Concerning...Severe potential...Watch possible
Valid 121143Z - 121345Z
Probability of Watch Issuance...40 percent
SUMMARY...Thunderstorms will continue moving across far southern
Alabama and the Florida Panhandle this morning, where a few damaging
wind gusts may occur. A watch may be needed.
DISCUSSION...Latest radar loop shows a semi-continuous band of
thunderstorms from far southern Alabama (Covington County) into
western portions of the Florida Panhandle and offshore into the
north-central Gulf of Mexico, moving eastward at 35 kt. The storms
are ongoing just ahead of a weak surface cold front, and in advance
of a compact vort max crossing the lower Mississippi Valley area at
this time.
While rather weak low-level flow is observed across the region,
amply strong mid-level westerlies are allowing some organization to
occur with the band, which has intensified over the past hour.
However, while sufficient elevated CAPE exists for storms to
persist, dewpoints generally in the low to mid 60s are indicative of
a roughly 100mb deep surface-based stable layer, which will likely
tend to limit any more widespread potential for damaging winds.
Still, where locally/transiently intense updrafts occur, a few
stronger gusts may penetrate to the surface, capable of producing
minor wind damage.
With the downstream low-level airmass across the Panhandle similarly
stable, extent of wind potential should remain limited. Still, we
will continue to monitor the region for any signs of further
organization, which could warrant issuance of a small WW.
..Goss/Guyer.. 05/12/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...TAE...MOB...
LAT...LON 30138732 31058672 31358610 31268532 31058497 30848453
30188413 29658420 29288478 29558574 29898639 30138732SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 12, 7:14 AM CDT | Severe Thunderstorm Watch | SPC | Coffee, Dale, Geneva, Henry, Houston | 6 hr |
| May 12, 9:17 AM CDT | Mesoscale Discussion | SPC | Henry, Houston | 118 min |
| May 12, 11:30 AM CDT | Mesoscale Discussion | SPC | Baker, Bay, Bradford, Calhoun, Clay, Columbia and 16 more | 2 hr |
Nearby
Mesoscale Discussions in Florida, 2021Mesoscale Discussions in Alabama, 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.