Alert archive / Florida / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 137, NWS Jacksonville, FL

June 20, 2020Saint Johns County, Florida

NWS Jacksonville, FL issued this severe thunderstorm warning at Jun 20, 2020, 6:11 PM EDT for Saint Johns County, Florida. It was in force for 20 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Jun 20, 2020, 6:11 PM EDT (22:11 UTC)
Expired: Jun 20, 2020, 6:31 PM EDT
In force: 20 min
Issued by: NWS Jacksonville, FL
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

County Saint Johns County, FL

The radar

The Jacksonville radar (KJAX), 70 km from the middle of the area, began a volume at 22:12 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

Jacksonville, FL (KJAX), launched 12:00Z, 10.2 hours before the alert went out and 71 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 562 J/kg
Mixed-layer CIN: -73 J/kg
Mixed-layer LCL: 901 m above ground
0-6 km bulk shear: 30 kt
0-1 km storm-relative helicity: 4 m²/s²
0-3 km storm-relative helicity: 56 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Jacksonville, FL wrote its last area forecast discussion before this severe thunderstorm warning went out at Jun 20, 1:46 PM EDT, 4 hours 25 minutes earlier.

Area forecast discussion, Jun 20, 1:46 PM EDT, 4 hours 25 minutes before

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In the hours before

Local storm report, Jun 20, 4:22 PM EDT, 1 hour 49 minutes before

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Special weather statement, Jun 20, 4:27 PM EDT, 1 hour 44 minutes before

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Local storm report, Jun 20, 4:36 PM EDT, 1 hour 35 minutes before

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Special weather statement, Jun 20, 4:48 PM EDT, 1 hour 23 minutes before

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Special weather statement, Jun 20, 5:37 PM EDT, 34 minutes before

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Special weather statement, Jun 20, 6:04 PM EDT, 7 minutes before

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The office that day

Everything else NWS Jacksonville, FL issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 20, 3:30 PM EDT	Special Weather Statement	JAX	Nassau	30 min
Jun 20, 3:59 PM EDT	Special Weather Statement	JAX	Duval	31 min
Jun 20, 4:17 PM EDT	Special Marine Warning	JAX		56 min
Jun 20, 4:27 PM EDT	Special Weather Statement	JAX	Duval	48 min
Jun 20, 5:37 PM EDT	Special Weather Statement	JAX	Saint Johns	38 min
Jun 20, 5:48 PM EDT	Severe Thunderstorm Warning	JAX	Duval, Saint Johns	42 min
Jun 20, 6:26 PM EDT	Special Weather Statement	JAX	Saint Johns	34 min
Jun 20, 6:33 PM EDT	Special Weather Statement	JAX	Saint Johns	42 min
Jun 19, 8:47 PM EDT	Special Weather Statement	JAX	Appling, Wayne	43 min
Jun 19, 8:52 PM EDT	Areal Flood Warning	JAX	Appling, Wayne	3 hr
Jun 19, 9:12 PM EDT	Special Weather Statement	JAX	Wayne	48 min
Jun 19, 9:19 PM EDT	Severe Thunderstorm Warning	JAX	Pierce, Wayne	41 min
Jun 19, 9:30 PM EDT	Tornado Warning	JAX	Brantley, Pierce, Wayne	30 min
Jun 19, 9:33 PM EDT	Special Weather Statement	JAX	Appling, Bacon	42 min
Jun 19, 9:55 PM EDT	Tornado Warning	JAX	Brantley, Pierce, Wayne	35 min
Jun 19, 10:27 PM EDT	Tornado Warning	JAX	Brantley, Pierce	33 min
Jun 19, 10:37 PM EDT	Special Weather Statement	JAX	Pierce	38 min
Jun 19, 10:53 PM EDT	Severe Thunderstorm Warning	JAX	Brantley, Pierce	37 min
Jun 19, 11:07 PM EDT	Special Weather Statement	JAX	Pierce	38 min
Jun 19, 11:28 PM EDT	Severe Thunderstorm Warning	JAX	Brantley, Ware	32 min
Jun 19, 11:57 PM EDT	Special Weather Statement	JAX	Brantley	33 min
Jun 20, 3:54 PM EDT	Special Weather Statement	JAX	Glynn	51 min
Jun 20, 4:48 PM EDT	Special Weather Statement	JAX	Glynn	42 min
Jun 20, 6:04 PM EDT	Special Weather Statement	JAX	Glynn	41 min
Jun 20, 6:13 PM EDT	Special Weather Statement	JAX	Pierce	47 min
Jun 20, 7:09 PM EDT	Special Weather Statement	JAX	Brantley	51 min

Nearby

Severe Thunderstorm Warnings in Florida, 2020 Every severe thunderstorm warning 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.