Alert archive / Florida / Mesoscale Discussions in 2021

Mesoscale Discussion 125

February 19, 202112 counties in Florida

The Storm Prediction Center issued this mesoscale discussion at Feb 19, 2021, 1:00 PM EST for 12 counties in Florida. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Feb 19, 2021, 1:00 PM EST (18:00 UTC)
Expired: Feb 19, 2021, 3:00 PM EST
In force: 2 hr
Issued by: the Storm Prediction Center
Concerning: Severe potential...watch unlikely
Chance of a watch: 5%

Counties Brevard County, FL, Glades County, FL, Hardee County, FL, Highlands County, FL, Indian River County, FL, Martin County, FL, Okeechobee County, FL, Orange County, FL, Osceola County, FL, Polk County, FL, Saint Lucie County, FL, Seminole County, FL

The radar

The Melbourne radar (KMLB), 63 km from the middle of the area, began a volume at 18:00 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

Tampa Bay, FL (KTBW), launched 12:00Z, 6.0 hours before the alert went out and 129 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 794 J/kg
Mixed-layer CIN: -24 J/kg
Mixed-layer LCL: 750 m above ground
0-6 km bulk shear: 46 kt
0-1 km storm-relative helicity: 219 m²/s²
0-3 km storm-relative helicity: 226 m²/s²
Significant tornado parameter: 0.8
Supercell composite: 5.0

Open this sounding in Storm Lab

The text

As transmitted.

674 
ACUS11 KWNS 191801
SWOMCD
SPC MCD 191800 
FLZ000-192000-

Mesoscale Discussion 0125
NWS Storm Prediction Center Norman OK
1200 PM CST Fri Feb 19 2021

Areas affected...Central/East-Central FL

Concerning...Severe potential...Watch unlikely 

Valid 191800Z - 192000Z

Probability of Watch Issuance...5 percent

SUMMARY...A strong storm or two, with the potential to produce gusty
downburst winds, may occur along and ahead of the front over the
next few hours.

DISCUSSION...A cold front continues to make steady southeastward
progress across the FL Peninsula. Forcing for ascent along the front
has led to occasional thunderstorms, although these storms have
quickly weakened once they become displaced north of the frontal
boundary. This overall trend is expected to continue, with the front
undercutting updrafts and limiting the overall spatial and temporal
threat for damaging wind gusts and/or tornadoes. 

However, recent regional radar imagery shows an increase in
pre-frontal development across central FL amid modest instability
and ascent. Much of the low-level flow has already veered
southwestward and mid-level lapse rates are poor. These factors have
limited updraft strength and persistence thus far. Even so,
pre-frontal convective coverage is expected to increase, with the
potential for a strong storm or two also increasing. Steep low-level
lapse rates across the region inflate the potential for a damaging
wind gust or two, particularly if a more robust cell interacts with
the cold front.

..Mosier/Goss.. 02/19/2021

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

ATTN...WFO...MFL...MLB...TBW...

LAT...LON   27748192 28718119 28928074 28108018 27398011 26738062
            26748134 27238184 27748192

Nearby

Mesoscale Discussions in Florida, 2021 Every 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.