Alert archive / Florida / Mesoscale Discussions in 2021

Mesoscale Discussion 1714

September 8, 2021Franklin County, Liberty County, Wakulla County, Florida

The Storm Prediction Center issued this mesoscale discussion at Sep 8, 2021, 3:13 PM EDT for Franklin County, Liberty County, Wakulla County, Florida. It was in force for 92 min.

The area

The outline as issued.

The facts

Issued
Sep 8, 2021, 3:13 PM EDT (19:13 UTC)
Expired
Sep 8, 2021, 4:45 PM EDT
In force
92 min
Issued by
the Storm Prediction Center
Concerning
Severe potential...watch unlikely
Chance of a watch
5%

Counties Franklin County, FL, Liberty County, FL, Wakulla County, FL

The radar

The Tallahassee radar (KTLH), 44 km from the middle of the area, began a volume at 19:17 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

Tallahassee Rgnl, FL (KTLH), launched 12:00Z, 7.2 hours before the alert went out and 46 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, Tallahassee Rgnl, FL at 12:00Z on 2021-09-08Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 881 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, Tallahassee Rgnl, FL at 12:00Z on 2021-09-08The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 15 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
881 J/kg
Mixed-layer CIN
-19 J/kg
Mixed-layer LCL
901 m above ground
0-6 km bulk shear
13 kt
0-1 km storm-relative helicity
15 m²/s²
0-3 km storm-relative helicity
51 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

956 
ACUS11 KWNS 081913
SWOMCD
SPC MCD 081913 
FLZ000-082045-

Mesoscale Discussion 1714
NWS Storm Prediction Center Norman OK
0213 PM CDT Wed Sep 08 2021

Areas affected...The Florida Panhandle

Concerning...Severe potential...Watch unlikely 

Valid 081913Z - 082045Z

Probability of Watch Issuance...5 percent

SUMMARY...A brief tornado may occur this afternoon, but the threat
is expected to remain too marginal for a watch.

DISCUSSION...A cluster of thunderstorms over the northeast Gulf of
Mexico has shown some signs of tropical cyclone formation, but the
overall structure of the system is still a bit disorganized. 
Likewise, only modest increases in flow/shear have been observed
over land, with a small, looping hodograph noted in the VWP data
from TLH.  The modest increase in vertical shear has been sufficient
for some weak supercell structures now approaching Franklin Co. FL. 
A brief tornado may occur as a supercell or two moves across the
coast, but the overall tornado threat is expected to remain marginal
and not extend more than a county inland.  Thus, a tornado watch
does not appear necessary at this time.

..Thompson/Hart.. 09/08/2021

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

ATTN...WFO...TAE...

LAT...LON   30128505 30438472 30438426 30298401 29988385 29798425
            29548482 29828514 30128505

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.