Alert archive / Florida / Mesoscale Discussions in 2021
Mesoscale Discussion 553
The Storm Prediction Center issued this mesoscale discussion at May 6, 2021, 3:06 PM EDT for 4 counties in Florida. It was in force for 114 min.
The area
The outline as issued.
The facts
- Issued
- May 6, 2021, 3:06 PM EDT (19:06 UTC)
- Expired
- May 6, 2021, 5:00 PM EDT
- In force
- 114 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 5%
Counties Broward County, FL, Martin County, FL, Miami-Dade County, FL, Palm Beach County, FL
The radar
The Miami radar (KAMX), 85 km from the middle of the area, began a volume at 19:06 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, 7.1 hours before the alert went out and 61 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
- 717 J/kg
- Mixed-layer CIN
- -52 J/kg
- Mixed-layer LCL
- 885 m above ground
- 0-6 km bulk shear
- 20 kt
- 0-1 km storm-relative helicity
- 4 m²/s²
- 0-3 km storm-relative helicity
- -15 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.2
The text
As transmitted.
758
ACUS11 KWNS 061906
SWOMCD
SPC MCD 061906
FLZ000-062100-
Mesoscale Discussion 0553
NWS Storm Prediction Center Norman OK
0206 PM CDT Thu May 06 2021
Areas affected...South FL
Concerning...Severe potential...Watch unlikely
Valid 061906Z - 062100Z
Probability of Watch Issuance...5 percent
SUMMARY...Thunderstorms are expected to increase in coverage this
afternoon and early evening. Isolated stronger storms will pose a
risk for strong, possibly damaging wind gusts. A watch is not
anticipated due to the localized nature of the risk.
DISCUSSION...Daytime heating of a moist low-level air mass (lower
70s surface dew points) has resulted in MLCAPE averaging 1000 to
locally 2000 J/kg across south FL as of 19z along with negligible
convective inhibition. The 18z MFL sounding sampled generally weak
westerly flow in the mid-upper levels, contributing to around 20 kts
of effective shear. Thunderstorm development is expected the
remainder of this afternoon in the vicinity of the nearly stationary
sea breeze boundary which extends from eastern Palm Beach County
southwestward into central Miami-Dade County, and also along the
west coast sea breeze as it continues moving east across South FL.
Steep low-level lapse rates will result in a risk for localized
strong/possibly damaging gusts as the primary severe risk as storms
move east/southeast through early evening. Due to the expected
isolated nature of the risk, a watch is not anticipated.
..Bunting/Grams.. 05/06/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MFL...MLB...KEY...TBW...
LAT...LON 25447987 25278024 25608067 26528100 27068119 27278086
27148029 27138004 26997985 26207982 25447987SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 6, 12:05 PM EDT | Mesoscale Discussion | SPC | Brevard, Indian River, Lake, Okeechobee, Orange, Osceola and 2 more | 115 min |
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.