Alert archive / Florida / Mesoscale Discussions in 2020

Mesoscale Discussion 1693

September 15, 20206 counties in Florida

The Storm Prediction Center issued this mesoscale discussion at Sep 15, 2020, 7:45 PM CDT for 6 counties in Florida. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Sep 15, 2020, 7:45 PM CDT (00:45 UTC)
Expired
Sep 15, 2020, 9:45 PM CDT
In force
2 hr
Issued by
the Storm Prediction Center
Concerning
Tornado watch 490

Counties Bay County, FL, Escambia County, FL, Franklin County, FL, Gulf County, FL, Okaloosa County, FL, Walton County, FL

The radar

The Eglin Afb radar (KEVX), 62 km from the middle of the area, began a volume at 00:46 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 00:00Z, 0.8 hours before the alert went out and 158 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 00:00Z on 2020-09-16Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 929 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, Tallahassee Rgnl, FL at 00:00Z on 2020-09-16The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 181 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
929 J/kg
Mixed-layer CIN
0 J/kg
Mixed-layer LCL
520 m above ground
0-6 km bulk shear
32 kt
0-1 km storm-relative helicity
181 m²/s²
0-3 km storm-relative helicity
228 m²/s²
Significant tornado parameter
0.7
Supercell composite
6.1

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Sep 15, 11:09 PM CDTMesoscale DiscussionSPCBay, Calhoun, Escambia, Franklin, Gulf, Liberty and 4 more2 hr
Sep 16, 4:14 AM CDTMesoscale DiscussionSPCBay, Calhoun, Escambia, Franklin, Gadsden, Gulf and 7 more2 hr
Sep 16, 5:55 AM CDTTornado WatchSPCBay, Calhoun, Dixie, Escambia, Franklin, Gadsden and 14 more14 hr
Sep 16, 11:18 AM CDTMesoscale DiscussionSPCBay, Calhoun, Franklin, Gadsden, Gulf, Holmes and 6 more102 min
Sep 16, 2:08 PM CDTMesoscale DiscussionSPCGadsden, Jefferson, Leon, Madison, Wakulla2 hr
Sep 16, 6:34 PM CDTMesoscale DiscussionSPCDuval, Nassau116 min

Nearby

Mesoscale Discussions in Florida, 2020Every mesoscale discussion in 2020

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.