Alert archive / Georgia / Mesoscale Discussions in 2020

Mesoscale Discussion 417

April 20, 202012 counties in Florida; 34 counties in Georgia; 7 counties in South Carolina

The Storm Prediction Center issued this mesoscale discussion at Apr 20, 2020, 1:52 AM EDT for 12 counties in Florida; 34 counties in Georgia; 7 counties in South Carolina. It was in force for 83 min.

The area

The outline as issued.

The facts

Issued
Apr 20, 2020, 1:52 AM EDT (05:52 UTC)
Expired
Apr 20, 2020, 3:15 AM EDT
In force
83 min
Issued by
the Storm Prediction Center
Chance of a watch
95%
All 53 counties

Alachua County, FL, Baker County, FL, Bradford County, FL, Clay County, FL, Columbia County, FL, Duval County, FL, Gilchrist County, FL, Hamilton County, FL, Lafayette County, FL, Nassau County, FL, Suwannee County, FL, Union County, FL, Appling County, GA, Atkinson County, GA, Bacon County, GA, Ben Hill County, GA, Berrien County, GA, Brantley County, GA, Bryan County, GA, Bulloch County, GA, Camden County, GA, Candler County, GA, Charlton County, GA, Chatham County, GA, Clinch County, GA, Coffee County, GA, Echols County, GA, Effingham County, GA, Evans County, GA, Glynn County, GA, Irwin County, GA, Jeff Davis County, GA, Lanier County, GA, Liberty County, GA, Long County, GA, McIntosh County, GA, Montgomery County, GA, Pierce County, GA, Screven County, GA, Tattnall County, GA, Telfair County, GA, Toombs County, GA, Treutlen County, GA, Ware County, GA, Wayne County, GA, Wheeler County, GA, Beaufort County, SC, Berkeley County, SC, Charleston County, SC, Colleton County, SC, Dorchester County, SC, Hampton County, SC, Jasper County, SC

The radar

The Jacksonville radar (KJAX), 108 km from the middle of the area, began a volume at 05:53 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

The nearest sounding before it

Jacksonville, FL (KJAX), launched 00:00Z, 5.9 hours before the alert went out and 106 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, Jacksonville, FL at 00:00Z on 2020-04-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 262 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, Jacksonville, FL at 00:00Z on 2020-04-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 165 square meters per square second.19395878Sfc1 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
262 J/kg
Mixed-layer CIN
-60 J/kg
Mixed-layer LCL
1615 m above ground
0-6 km bulk shear
49 kt
0-1 km storm-relative helicity
165 m²/s²
0-3 km storm-relative helicity
227 m²/s²
Significant tornado parameter
0.1
Supercell composite
3.2

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
Apr 19, 10:39 PM EDTTornado WatchSPCEscambia, Okaloosa, Santa Rosa5 hr
Apr 19, 10:53 PM EDTMesoscale DiscussionSPCGadsden, Holmes, Jackson, Walton, Washington67 min
Apr 19, 11:13 PM EDTTornado WatchSPCBay, Calhoun, Dixie, Franklin, Gadsden, Gulf and 11 more10 hr
Apr 20, 2:19 AM EDTTornado WatchSPCAlachua, Baker, Bradford, Clay, Columbia, Duval and 9 more9 hr
Apr 20, 6:19 AM EDTMesoscale DiscussionSPCAlachua, Baker, Bradford, Citrus, Clay, Columbia and 16 more86 min
Apr 20, 7:02 AM EDTSevere Thunderstorm WatchSPCBrevard, Citrus, Hardee, Hernando, Hillsborough, Lake and 11 more8 hr
Apr 20, 8:18 AM EDTMesoscale DiscussionSPCAlachua, Citrus, Flagler, Levy, Marion, Putnam and 2 more87 min
Apr 20, 11:06 AM EDTMesoscale DiscussionSPCBrevard, Hardee, Hernando, Hillsborough, Indian River, Lake and 10 more114 min
Apr 20, 2:00 PM EDTMesoscale DiscussionSPCDeSoto, Hardee, Highlands, Indian River, Manatee, Okeechobee and 4 more90 min
Apr 19, 9:25 PM EDTMesoscale DiscussionSPCBaker, Calhoun, Chattahoochee, Clay, Early, Marion and 6 more65 min

Nearby

Mesoscale Discussions in Georgia, 2020Mesoscale Discussions in Florida, 2020Mesoscale Discussions in South Carolina, 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.