Alert archive / Florida / Mesoscale Discussions in 2021

Mesoscale Discussion 1926

October 28, 20216 counties in Florida

The Storm Prediction Center issued this mesoscale discussion at Oct 28, 2021, 8:49 PM EDT for 6 counties in Florida. It was in force for 86 min.

The area

The outline as issued.

The facts

Issued
Oct 28, 2021, 8:49 PM EDT (00:49 UTC)
Expired
Oct 28, 2021, 10:15 PM EDT
In force
86 min
Issued by
the Storm Prediction Center
Concerning
Severe potential...watch unlikely
Chance of a watch
5%

Counties Broward County, FL, Collier County, FL, Hendry County, FL, Miami-Dade County, FL, Monroe County, FL, Palm Beach County, FL

The radar

The Miami radar (KAMX), 57 km from the middle of the area, began a volume at 00:50 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 00:00Z, 0.8 hours before the alert went out and 63 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.

Skew-T log-pSkew-T log-p diagram, Miami, FL at 00:00Z on 2021-10-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1336 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Miami, FL at 00:00Z on 2021-10-29The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 111 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
1336 J/kg
Mixed-layer CIN
-15 J/kg
Mixed-layer LCL
891 m above ground
0-6 km bulk shear
29 kt
0-1 km storm-relative helicity
111 m²/s²
0-3 km storm-relative helicity
117 m²/s²
Significant tornado parameter
0.6
Supercell composite
3.2

Open this sounding in Storm Lab

The text

As transmitted.

109 
ACUS11 KWNS 290049
SWOMCD
SPC MCD 290049 
FLZ000-290215-

Mesoscale Discussion 1926
NWS Storm Prediction Center Norman OK
0749 PM CDT Thu Oct 28 2021

Areas affected...South Florida

Concerning...Severe potential...Watch unlikely 

Valid 290049Z - 290215Z

Probability of Watch Issuance...5 percent

SUMMARY...A marginal damaging wind threat will continue for a few
more hours.

DISCUSSION...A cluster of storms has moved on shore near Naples. The
00Z MFL RAOB shows around 1300 J/kg MLCAPE ahead of these storms
with effective shear around 35 knots. This should be sufficient for
maintenance of ongoing activity. However, weak lapse rates and high
freezing levels will limit the hail threat and mostly unidirectional
low-level shear should keep the tornado threat mostly subdued. An
occasional damaging wind gust cannot be ruled out, especially where
precipitation loading can strengthen downdrafts. However, even this
threat is quite marginal given the relatively warm temperatures in
the lowest 4-5km which will likely quell stronger updraft
development and likely keep downdraft wind speeds below severe
limits.

..Bentley/Grams.. 10/29/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...MFL...KEY...TBW...

LAT...LON   26238189 26728100 26968003 26248000 25398021 25198038
            25198072 25148102 25338128 25748171 26238189

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.