Alert archive / Florida / Mesoscale Discussions in 2021
Mesoscale Discussion 397
The Storm Prediction Center issued this mesoscale discussion at Apr 18, 2021, 9:35 PM EDT for 13 counties in Florida. It was in force for 85 min.
The area
The outline as issued.
The facts
- Issued
- Apr 18, 2021, 9:35 PM EDT (01:35 UTC)
- Expired
- Apr 18, 2021, 11:00 PM EDT
- In force
- 85 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 5%
Counties Brevard County, FL, Hardee County, FL, Hernando County, FL, Hillsborough County, FL, Lake County, FL, Manatee County, FL, Orange County, FL, Osceola County, FL, Pasco County, FL, Pinellas County, FL, Polk County, FL, Seminole County, FL, Sumter County, FL
The radar
The Tampa radar (KTBW), 77 km from the middle of the area, began a volume at 01:37 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
Tampa Bay, FL (KTBW), launched 00:00Z, 1.6 hours before the alert went out and 77 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
- 1430 J/kg
- Mixed-layer CIN
- -14 J/kg
- Mixed-layer LCL
- 988 m above ground
- 0-6 km bulk shear
- 42 kt
- 0-1 km storm-relative helicity
- 51 m²/s²
- 0-3 km storm-relative helicity
- 66 m²/s²
- Significant tornado parameter
- 0.3
- Supercell composite
- 2.0
The text
As transmitted.
363
ACUS11 KWNS 190136
SWOMCD
SPC MCD 190135
FLZ000-190300-
Mesoscale Discussion 0397
NWS Storm Prediction Center Norman OK
0835 PM CDT Sun Apr 18 2021
Areas affected...the central Florida Peninsula.
Concerning...Severe potential...Watch unlikely
Valid 190135Z - 190300Z
Probability of Watch Issuance...5 percent
SUMMARY...A line of storms will cross the Florida Peninsula during
the late evening/early overnight hours with a threat for isolated
damaging wind gusts. Current indications are that severe weather
intensity and coverage will be too limited to need a watch.
DISCUSSION...A loosely organized line of storms is currently
approaching the Florida coast west of Tampa. These storms have
formed ahead of a weak MCV which can be seen from KTBW WSR-88D base
reflectivity. This MCV is likely aiding the organization and the
best strong to isolated severe storm threat will likely remain in
close proximity to this feature as it crosses the peninsula. In
addition, some strengthening low-level flow is being observed around
1km in the KTBW VWP. This may also increase the likelihood of a
damaging wind gust or two as the line of storms crosses the Florida
Peninsula.
..Bentley/Hart.. 04/19/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MLB...TBW...
LAT...LON 28438282 28698225 29018124 29048083 28358040 27828029
27538135 27408271 27658282 27898289 28438282SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 19, 4:36 AM EDT | Mesoscale Discussion | SPC | Brevard, DeSoto, Hardee, Highlands, Hillsborough, Indian River and 5 more | 2 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.