Alert archive / Florida / Mesoscale Discussions in 2021
Mesoscale Discussion 365
The Storm Prediction Center issued this mesoscale discussion at Apr 11, 2021, 5:27 AM EDT for 20 counties in Florida. It was in force for 3 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 11, 2021, 5:27 AM EDT (09:27 UTC)
- Expired
- Apr 11, 2021, 8:00 AM EDT
- In force
- 3 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 40%
Counties Alachua County, FL, Bradford County, FL, Citrus County, FL, Clay County, FL, Dixie County, FL, Flagler County, FL, Gilchrist County, FL, Hernando County, FL, Lafayette County, FL, Lake County, FL, Levy County, FL, Marion County, FL, Orange County, FL, Putnam County, FL, Seminole County, FL, Sumter County, FL, Suwannee County, FL, Taylor County, FL, Union County, FL, Volusia County, FL
The radar
The Jacksonville radar (KJAX), 127 km from the middle of the area, began a volume at 09:28 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
Jacksonville, FL (KJAX), launched 00:00Z, 9.5 hours before the alert went out and 128 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
- 1585 m above ground
- 0-6 km bulk shear
- 63 kt
- 0-1 km storm-relative helicity
- 156 m²/s²
- 0-3 km storm-relative helicity
- 219 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
566
ACUS11 KWNS 110928
SWOMCD
SPC MCD 110927
FLZ000-111200-
Mesoscale Discussion 0365
NWS Storm Prediction Center Norman OK
0427 AM CDT Sun Apr 11 2021
Areas affected...Northern Florida Peninsula
Concerning...Severe potential...Watch possible
Valid 110927Z - 111200Z
Probability of Watch Issuance...40 percent
SUMMARY...Isolated large hail will be possible across the northern
Florida Peninsula over the next few hours. Weather watch issuance
will need to be considered as cells gradually increase in coverage.
DISCUSSION...Latest surface analysis shows 1009 mb low over the
eastern Florida Peninsula. A moist airmass is located across much of
the Florida Peninsula where surface dewpoints range from the mid 70s
F in south Florida to the upper 50s F in north-central Florida.
Thunderstorms have been developing in the northeast Gulf of Mexico
in response to warm advection. Additional elevated storms are
ongoing across the northern Florida Peninsula. The RAP shows
effective shear in the 35 to 45 kt range over land but near 50 kt
over the water where the CAPE is closer to surface-based. The RAP is
also showing mid-level lapse rate near 7.5 C/km across north-central
Florida. This environment should support isolated large hail with
the stronger rotating storms. The hail threat may gradually increase
as storm coverage expands over the next few hours.
..Broyles/Edwards.. 04/11/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MLB...TBW...JAX...TAE...
LAT...LON 30078204 29818125 29438098 28998081 28638083 28458100
28308232 29178322 29708394 29958407 30208394 30268332
30078204SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 11, 8:15 AM EDT | Severe Thunderstorm Watch | SPC | Alachua, Brevard, Citrus, DeSoto, Dixie, Flagler and 23 more | 8 hr |
| Apr 11, 10:54 AM EDT | Mesoscale Discussion | SPC | Brevard, Citrus, Hernando, Hillsborough, Lake, Manatee and 9 more | 2 hr |
| Apr 11, 12:08 PM EDT | Mesoscale Discussion | SPC | Brevard, Hillsborough, Manatee, Orange, Osceola, Polk and 1 more | 2 hr |
| Apr 11, 1:24 PM EDT | Mesoscale Discussion | SPC | Broward, Charlotte, Collier, DeSoto, Glades, Hardee and 11 more | 2 hr |
| Apr 11, 2:03 PM EDT | Severe Thunderstorm Watch | SPC | Broward, Charlotte, Collier, Glades, Hendry, Lee and 3 more | 6 hr |
| Apr 11, 4:12 PM EDT | Mesoscale Discussion | SPC | Broward, Collier, Hendry, Lee | 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.