Alert archive / Florida / Mesoscale Discussions in 2021
Mesoscale Discussion 985
The Storm Prediction Center issued this mesoscale discussion at Jun 16, 2021, 7:39 PM EDT for Collier County, Miami-Dade County, Monroe County, Florida. It was in force for 96 min.
The area
The outline as issued.
The facts
- Issued
- Jun 16, 2021, 7:39 PM EDT (23:39 UTC)
- Expired
- Jun 16, 2021, 9:15 PM EDT
- In force
- 96 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 5%
Counties Collier County, FL, Miami-Dade County, FL, Monroe County, FL
The radar
The Miami radar (KAMX), 49 km from the middle of the area, began a volume at 23:41 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, 11.7 hours before the alert went out and 62 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
- 1282 J/kg
- Mixed-layer CIN
- -66 J/kg
- Mixed-layer LCL
- 933 m above ground
- 0-6 km bulk shear
- 15 kt
- 0-1 km storm-relative helicity
- 34 m²/s²
- 0-3 km storm-relative helicity
- 76 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.0
The text
As transmitted.
516
ACUS11 KWNS 162339
SWOMCD
SPC MCD 162339
FLZ000-170115-
Mesoscale Discussion 0985
NWS Storm Prediction Center Norman OK
0639 PM CDT Wed Jun 16 2021
Areas affected...South FL
Concerning...Severe potential...Watch unlikely
Valid 162339Z - 170115Z
Probability of Watch Issuance...5 percent
SUMMARY...A damaging wind gust or two may occur with the convective
line moving into South Florida.
DISCUSSION...Radar imagery shows a fast-moving convective line
extending from about 50 miles southwest of APF (off the southeast FL
coast) to about 40 miles northeast MTH/50 miles south-southwest of
MIA (just off the far southern FL coast). Recent estimates place the
motion of this line around 35 kt, which matches the recent gust at
MTH as the line moved through. Recent KAMX radar imagery also shows
a pocket of stronger inbound velocities around 3000 ft within the
leading edge of the line 10 miles or so south of the southern
Miami-Dade County line. Increased forward motion was also noted
within this portion of the line. This surge may have been associated
with interaction with a southwestward moving outflow, which briefly
strengthened updrafts/downdrafts.
Instability downstream across most of southern FL has recently been
tempered by abundant cloud cover and ongoing showers and
thunderstorms. Deep layer shear is also weaker across south FL than
the environment over the FL Keys. The outflow is expected to
continue northeastward, but the modest instability and weak shear
should keep storm intensity along the boundary rather limited, with
a diminishing trend expected over time. Even so, a few stronger,
water-loaded downbursts may still occur, augmenting the storm motion
and leading to isolated damaging wind gusts.
..Mosier/Guyer.. 06/16/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MFL...KEY...
LAT...LON 25838195 26168148 26118080 26018038 25858013 25528005
25128024 25068056 25348139 25838195Nearby
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.