Alert archive / Florida / Mesoscale Discussions in 2021

Mesoscale Discussion 1166

July 6, 202115 counties in Florida

The Storm Prediction Center issued this mesoscale discussion at Jul 6, 2021, 4:55 PM EDT for 15 counties in Florida. It was in force for 95 min.

The area

The outline as issued.

The facts

Issued
Jul 6, 2021, 4:55 PM EDT (20:55 UTC)
Expired
Jul 6, 2021, 6:30 PM EDT
In force
95 min
Issued by
the Storm Prediction Center
Concerning
Tornado watch 337

Counties Charlotte County, FL, Collier County, FL, DeSoto County, FL, Glades County, FL, Hardee County, FL, Hendry County, FL, Highlands County, FL, Hillsborough County, FL, Lee County, FL, Manatee County, FL, Monroe County, FL, Okeechobee County, FL, Pinellas County, FL, Polk County, FL, Sarasota County, FL

The radar

The Tampa radar (KTBW), 155 km from the middle of the area, began a volume at 20:56 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, 8.9 hours before the alert went out and 155 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, Tampa Bay, FL at 12:00Z on 2021-07-06Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 815 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, Tampa Bay, FL at 12:00Z on 2021-07-06The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 29 square meters per square second.1939Sfc1 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
815 J/kg
Mixed-layer CIN
-46 J/kg
Mixed-layer LCL
773 m above ground
0-6 km bulk shear
9 kt
0-1 km storm-relative helicity
29 m²/s²
0-3 km storm-relative helicity
25 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

004 
ACUS11 KWNS 062056
SWOMCD
SPC MCD 062055 
FLZ000-062230-

Mesoscale Discussion 1166
NWS Storm Prediction Center Norman OK
0355 PM CDT Tue Jul 06 2021

Areas affected...Southern/central Florida and the FL Keys

Concerning...Tornado Watch 337...

Valid 062055Z - 062230Z

The severe weather threat for Tornado Watch 337 continues.

SUMMARY...The threat for a few tornadoes continues across the watch
area through this evening.

DISCUSSION...Tropical Storm Elsa continues to move north at 10 mph
west of the Florida west coast, and was located 155 miles south
southwest of Tampa at 2045z (see the latest NHC advisory for
complete details).  Low-level wind fields will strengthen slightly
over the next several hours as the system continues to slowly
intensify, and this will result in an increase in effective SRH
across portions of southern/central FL.  Latest hi-res guidance
suggests an uptick in the intensity of outer bands across mainly
western portions of the watch area this evening, with a
corresponding increase in the risk for a few tornadoes.

..Bunting.. 07/06/2021

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

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

LAT...LON   28158323 28258139 27298069 25788056 24908072 24608149
            24538191 26358246 28158323

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 6, 10:34 AM EDTMesoscale DiscussionSPCCharlotte, Collier, DeSoto, Glades, Hardee, Hendry and 12 more2 hr
Jul 6, 1:47 PM EDTTornado WatchSPCBroward, Charlotte, Collier, DeSoto, Glades, Hardee and 15 more9 hr
Jul 6, 7:17 PM EDTMesoscale DiscussionSPCCharlotte, Collier, Lee3 hr

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.