Alert archive / Florida / Mesoscale Discussions in 2021

Mesoscale Discussion 946

June 13, 202115 counties in Florida

The Storm Prediction Center issued this mesoscale discussion at Jun 13, 2021, 1:36 PM EDT for 15 counties in Florida. It was in force for 114 min.

The area

The outline as issued.

The facts

Issued
Jun 13, 2021, 1:36 PM EDT (17:36 UTC)
Expired
Jun 13, 2021, 3:30 PM EDT
In force
114 min
Issued by
the Storm Prediction Center
Concerning
Severe potential...watch unlikely
Chance of a watch
5%

Counties Alachua County, FL, Citrus County, FL, Dixie County, FL, Gilchrist County, FL, Hernando County, FL, Lake County, FL, Levy County, FL, Marion County, FL, Orange County, FL, Pasco County, FL, Polk County, FL, Putnam County, FL, Seminole County, FL, Sumter County, FL, Volusia County, FL

The radar

The Tampa radar (KTBW), 134 km from the middle of the area, began a volume at 17:38 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, 5.6 hours before the alert went out and 134 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 2021-06-13Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1681 joules per kilogram.LCLEL10008507005003002001001 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 2021-06-13The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 60 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
1681 J/kg
Mixed-layer CIN
-2 J/kg
Mixed-layer LCL
702 m above ground
0-6 km bulk shear
20 kt
0-1 km storm-relative helicity
60 m²/s²
0-3 km storm-relative helicity
89 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.4

Open this sounding in Storm Lab

The text

As transmitted.

670 
ACUS11 KWNS 131736
SWOMCD
SPC MCD 131736 
FLZ000-131930-

Mesoscale Discussion 0946
NWS Storm Prediction Center Norman OK
1236 PM CDT Sun Jun 13 2021

Areas affected...portions of the central Florida Peninsula

Concerning...Severe potential...Watch unlikely 

Valid 131736Z - 131930Z

Probability of Watch Issuance...5 percent

SUMMARY...A couple damaging gusts are possible with the stronger
storms this afternoon. A WW issuance is not expected.

DISCUSSION...Pulse convection/transient multicellular clusters have
been gradually intensifying through the late morning/early afternoon
hours, amidst a moisture-rich low-level environment. Though
mid-level lapse rates are poor, low-level lapse rates are
approaching 8 C/km in spots, contributing to over 150 J/kg 0-3 km
CAPE and over 1500-2500 J/kg MLCAPE (per 15Z XMR observed sounding
and 17Z mesoanalysis). As such, a couple damaging gusts may
accompany the stronger storms. Nonetheless, the tall-skinny CAPE
profile evident via the 15Z XMR sounding suggests that the severe
gust threat should be somewhat limited, with a WW issuance unlikely.

..Squitieri/Grams.. 06/13/2021

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

ATTN...WFO...MLB...TBW...JAX...TAE...

LAT...LON   29738341 29898237 29728171 29258098 28798065 28278093
            27928143 27898185 28018228 28218276 29738341

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.