Alert archive / Florida / Mesoscale Discussions in 2021
Mesoscale Discussion 432
The Storm Prediction Center issued this mesoscale discussion at Apr 25, 2021, 2:15 AM EDT for 13 counties in Florida. It was in force for 3 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 25, 2021, 2:15 AM EDT (06:15 UTC)
- Expired
- Apr 25, 2021, 4:45 AM EDT
- In force
- 3 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 5%
Counties Alachua County, FL, Baker County, FL, Bradford County, FL, Clay County, FL, Columbia County, FL, Dixie County, FL, Duval County, FL, Gilchrist County, FL, Lafayette County, FL, Nassau County, FL, Putnam County, FL, Saint Johns County, FL, Union County, FL
The radar
The Jacksonville radar (KJAX), 64 km from the middle of the area, began a volume at 06:18 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
Jacksonville, FL (KJAX), launched 00:00Z, 6.3 hours before the alert went out and 65 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
- 64 J/kg
- Mixed-layer CIN
- -157 J/kg
- Mixed-layer LCL
- 850 m above ground
- 0-6 km bulk shear
- 56 kt
- 0-1 km storm-relative helicity
- 275 m²/s²
- 0-3 km storm-relative helicity
- 358 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 2.9
The text
As transmitted.
152
ACUS11 KWNS 250615
SWOMCD
SPC MCD 250615
FLZ000-GAZ000-250845-
Mesoscale Discussion 0432
NWS Storm Prediction Center Norman OK
0115 AM CDT Sun Apr 25 2021
Areas affected...northern Florida and extreme southeastern Georgia
Concerning...Severe potential...Watch unlikely
Valid 250615Z - 250845Z
Probability of Watch Issuance...5 percent
SUMMARY...Isolated, marginally severe hail or wind remains possible
in the near term, but the threat is expected to decrease with time.
DISCUSSION...A line of storms currently extends from an offshore MCS
southwestward across far southeastern GA and into northern FL. These
storms are well ahead of the cold front, and oriented close to an
850 mb confluence line. Low 70s F dewpoints exist ahead of this
line, the exception being near Jacksonville FL where cooler air and
low-level inversion exist. The VWP from JAX shows ample deep-layer
shear, along with some low-level veering with height. Both long
hodographs and cool midlevel temperatures may support marginal hail,
with a few strong gusts. A supercell cannot be ruled out as the
deep-layer shear vector remains veered relative to the confluence
line, with 150-200 m2/s2 effective SRH.
As the shortwave trough exits the area, low-level winds will veer
further, providing drying aloft and reducing lift. Therefore, while
a few storms (some marginally severe) may persist over northern FL
tonight, conditions do not appear favorable for further
organization.
..Jewell/Edwards.. 04/25/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...TBW...JAX...TAE...
LAT...LON 29678113 29268319 29438337 29728357 29828365 30178290
30528237 30888169 30948135 30698135 30288132 29958123
29678113SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 24, 8:48 PM EDT | Severe Thunderstorm Watch | SPC | Holmes, Jackson | 4 hr |
Nearby
Mesoscale Discussions in Florida, 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.