Alert archive / Florida / Mesoscale Discussions in 2021
Mesoscale Discussion 1264
The Storm Prediction Center issued this mesoscale discussion at Jul 12, 2021, 11:51 AM EDT for 24 counties in Florida. It was in force for 114 min.
The area
The outline as issued.
The facts
- Issued
- Jul 12, 2021, 11:51 AM EDT (15:51 UTC)
- Expired
- Jul 12, 2021, 1:45 PM EDT
- In force
- 114 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 40%
All 24 counties
Alachua County, FL, Charlotte County, FL, Citrus County, FL, DeSoto County, FL, Gilchrist County, FL, Glades County, FL, Hardee County, FL, Hendry County, FL, Hernando County, FL, Highlands County, FL, Hillsborough County, FL, Lake County, FL, Lee County, FL, Levy County, FL, Manatee County, FL, Marion County, FL, Okeechobee County, FL, Orange County, FL, Osceola County, FL, Pasco County, FL, Pinellas County, FL, Polk County, FL, Sarasota County, FL, Sumter County, FL
The radar
The Tampa radar (KTBW), 69 km from the middle of the area, began a volume at 15:51 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 12:00Z, 3.9 hours before the alert went out and 69 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
- 1557 J/kg
- Mixed-layer CIN
- -32 J/kg
- Mixed-layer LCL
- 960 m above ground
- 0-6 km bulk shear
- 14 kt
- 0-1 km storm-relative helicity
- -21 m²/s²
- 0-3 km storm-relative helicity
- -26 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
908
ACUS11 KWNS 121552
SWOMCD
SPC MCD 121551
FLZ000-121745-
Mesoscale Discussion 1264
NWS Storm Prediction Center Norman OK
1051 AM CDT Mon Jul 12 2021
Areas affected...portions of the FL Peninsula
Concerning...Severe potential...Watch possible
Valid 121551Z - 121745Z
Probability of Watch Issuance...40 percent
SUMMARY...Sporadic strong, locally damaging wind gusts and hail will
be possible with more intense thunderstorms this afternoon across
parts of the Florida Peninsula.
DISCUSSION...Thunderstorms are developing across southern FL, moving
toward the central peninsula, in the vicinity of an outflow boundary
from overnight/early morning convection. Additional convection is
also beginning to develop over eastern portions of the peninsula in
developing sea breeze and deep southeasterly flow. Moderate to
strong instability is already in place with dewpoints well into the
70s F amid strong surface heating and modest midlevel cooling.
Little to no inhibition remains over the region, and convection
should continue to increase in coverage over the next couple of
hours as storms track toward the northwest.
Deep layer flow will generally remain weak over the region and this
will inhibit storm organization somewhat. Nevertheless, steep
midlevel lapse rates and strong instability should compensate and
allow for at least briefly intense cells within thunderstorm
clusters. High PW values also will help contribute to damaging wind
potential via wet microburst processes. Some hail also could briefly
accompany any more intense cells, but longevity of intense updrafts
should remain limited given weak vertical shear. Trends will be
monitored for possible watch issuance this afternoon.
..Leitman/Dial.. 07/12/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MFL...MLB...TBW...JAX...TAE...
LAT...LON 29628308 29828274 29798232 29608200 29198155 28618109
28288095 27158086 26668081 26608082 26538103 26448175
26648220 26998255 27768291 28538290 29198318 29558314
29628308Nearby
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.