Alert archive / Florida / Mesoscale Discussions in 2021

Mesoscale Discussion 557

May 7, 2021Broward County, Miami-Dade County, Florida

The Storm Prediction Center issued this mesoscale discussion at May 7, 2021, 3:47 PM EDT for Broward County, Miami-Dade County, Florida. It was in force for 118 min.

The area

The outline as issued.

The facts

Issued
May 7, 2021, 3:47 PM EDT (19:47 UTC)
Expired
May 7, 2021, 5:45 PM EDT
In force
118 min
Issued by
the Storm Prediction Center
Concerning
Severe potential...watch unlikely
Chance of a watch
5%

Counties Broward County, FL, Miami-Dade County, FL

The radar

The Miami radar (KAMX), 42 km from the middle of the area, began a volume at 19:51 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

Miami, FL (KMFL), launched 12:00Z, 7.8 hours before the alert went out and 30 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 12:00Z on 2021-05-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1218 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 12:00Z on 2021-05-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 23 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
1218 J/kg
Mixed-layer CIN
-39 J/kg
Mixed-layer LCL
874 m above ground
0-6 km bulk shear
28 kt
0-1 km storm-relative helicity
23 m²/s²
0-3 km storm-relative helicity
53 m²/s²
Significant tornado parameter
0.1
Supercell composite
0.6

Open this sounding in Storm Lab

The text

As transmitted.

975 
ACUS11 KWNS 071947
SWOMCD
SPC MCD 071947 
FLZ000-072145-

Mesoscale Discussion 0557
NWS Storm Prediction Center Norman OK
0247 PM CDT Fri May 07 2021

Areas affected...South FL

Concerning...Severe potential...Watch unlikely 

Valid 071947Z - 072145Z

Probability of Watch Issuance...5 percent

SUMMARY...Isolated damaging wind gusts are possible across south
Florida this afternoon.

DISCUSSION...Recent surface analysis places a cold front just north
of APF eastward to about 20 miles south of PBI. This front is
gradually moving southward. Additionally, visible satellite imagery
reveals the eastward-moving sea-breeze boundary well, which extends
in an arc from just north of MKY to about 20-25 miles
south-southwest of MIA. The small area south of the cold front and
east of the sea breeze has shown increasingly deep cu over the past
half hour as well as several attempts at deep convection. 

Expectation is for these attempts at convective initiation to
continue, with at least some chance a few thunderstorms develop this
afternoon before the progression of these boundaries pushes
development offshore. If deep convection is realized, the relatively
high LCL and steep low-level lapses rate sampled on the 18Z MFL
sounding reveal an environment favorable for wet microbursts capable
of damaging wind gusts.

..Mosier/Thompson.. 05/07/2021

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

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

LAT...LON   26158120 26348046 26408006 25807985 25258031 25688071
            26158120

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.