Alert archive / Florida / Mesoscale Discussions in 2021
Mesoscale Discussion 395
The Storm Prediction Center issued this mesoscale discussion at Apr 17, 2021, 4:43 PM EDT for 17 counties in Florida. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 17, 2021, 4:43 PM EDT (20:43 UTC)
- Expired
- Apr 17, 2021, 6:45 PM EDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
Counties Alachua County, FL, Bay County, FL, Bradford County, FL, Calhoun County, FL, Columbia County, FL, Dixie County, FL, Franklin County, FL, Gilchrist County, FL, Gulf County, FL, Jefferson County, FL, Lafayette County, FL, Levy County, FL, Liberty County, FL, Suwannee County, FL, Taylor County, FL, Union County, FL, Wakulla County, FL
The radar
The Tallahassee radar (KTLH), 72 km from the middle of the area, began a volume at 20:46 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, 8.7 hours before the alert went out and 72 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 718 m above ground
- 0-6 km bulk shear
- 54 kt
- 0-1 km storm-relative helicity
- 136 m²/s²
- 0-3 km storm-relative helicity
- 180 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
645
ACUS11 KWNS 172043
SWOMCD
SPC MCD 172043
FLZ000-172245-
Mesoscale Discussion 0395
NWS Storm Prediction Center Norman OK
0343 PM CDT Sat Apr 17 2021
Areas affected...portions of the FL Panhandle and northern FL
Peninsula
Concerning...Severe potential...Watch unlikely
Valid 172043Z - 172245Z
Probability of Watch Issuance...20 percent
SUMMARY...Thunderstorms are expected to increase across the
northeast Gulf of Mexico and move across portions of the FL
Panhandle and northwest FL peninsula through this evening. An
isolated stronger storm may produce strong wind gusts and perhaps
hail, but a watch is not currently anticipated.
DISCUSSION...Thunderstorms are expected to increase in coverage
across the northeast Gulf of Mexico and portions of the FL
Panhandle/northern FL peninsula in the vicinity of a nearly
stationary front. Modest warm advection combined with ascent
associated within the right entrance region of an approaching 300-mb
speed maxima will contribute to the thunderstorm development, with
storms moving east across the discussion area through this evening.
The front should begin to lift slowly north tonight and, despite
poor mid-level lapse rates, RAP forecast soundings depict MUCAPE
averaging 500 to locally 1000 J/kg this afternoon/evening. Strong
westerly mid-level flow will contribute to ample shear for organized
storms. As storms develop/move east over the next several hours the
potential will exist for a couple of storms to produce strong
surface wind gusts and perhaps hail. Any sustained storm in the
vicinity of the front across the northern peninsula this evening
would have at least some potential for a tornado given
modestly-enhanced low-level SRH.
The expected severe coverage should remain isolated and a watch is
not anticipated.
..Bunting/Dial.. 04/17/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...TBW...JAX...TAE...
LAT...LON 29388483 29458561 29658604 30238617 30468544 30458379
30408306 30258196 29568175 29178220 29038328 29388483Nearby
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.