Alert archive / Florida / Mesoscale Discussions in 2021
Mesoscale Discussion 822
The Storm Prediction Center issued this mesoscale discussion at May 31, 2021, 11:50 AM EDT for 19 counties in Florida. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- May 31, 2021, 11:50 AM EDT (15:50 UTC)
- Expired
- May 31, 2021, 2:15 PM EDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 5%
Counties Broward County, FL, Charlotte County, FL, Collier County, FL, DeSoto County, FL, Glades County, FL, Hardee County, FL, Hendry County, FL, Highlands County, FL, Hillsborough County, FL, Indian River County, FL, Manatee County, FL, Martin County, FL, Miami-Dade County, FL, Monroe County, FL, Okeechobee County, FL, Osceola County, FL, Palm Beach County, FL, Polk County, FL, Saint Lucie County, FL
The radar
The Miami radar (KAMX), 146 km from the middle of the area, began a volume at 15:52 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
Miami, FL (KMFL), launched 12:00Z, 3.8 hours before the alert went out and 134 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
- 1852 J/kg
- Mixed-layer CIN
- -8 J/kg
- Mixed-layer LCL
- 869 m above ground
- 0-6 km bulk shear
- 12 kt
- 0-1 km storm-relative helicity
- -4 m²/s²
- 0-3 km storm-relative helicity
- 10 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
453
ACUS11 KWNS 311550
SWOMCD
SPC MCD 311550
FLZ000-311815-
Mesoscale Discussion 0822
NWS Storm Prediction Center Norman OK
1050 AM CDT Mon May 31 2021
Areas affected...south Florida
Concerning...Severe potential...Watch unlikely
Valid 311550Z - 311815Z
Probability of Watch Issuance...5 percent
SUMMARY...Thunderstorms capable of strong, gusty winds and small
hail will be possible this afternoon. The localized nature of any
severe threat should prevent the need for a watch.
DISCUSSION...Thunderstorms should develop in the next few hours in
association with increasing low-level convergence along and near the
Gulf Coast sea-breeze. With a weak upper trough over the area
contributing to slightly cooler mid-level temperatures, the
background environment across south Florida will remain largely
unstable, with most-unstable CAPE values in excess of 3000 J/kg.
Despite this degree of instability, effective-layer shear will
remain generally at or below 20 knots, limiting thunderstorm
organization and favoring storm-scale interactions with the
sea-breeze to sustain updrafts. The most likely severe threat with
any thunderstorm will be strong, gusty thunderstorm outflows,
although small to marginally severe hail will also be possible.
The localized nature of any severe potential should preclude the
need for any watch this afternoon.
..Marsh/Hart.. 05/31/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MFL...MLB...TBW...
LAT...LON 25318090 26418185 27328244 27958255 28438180 28308083
27568045 26758010 25758017 25268044 25318090Nearby
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.