Alert archive / Florida / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 200, NWS Jacksonville, FL

August 18, 2020Saint Johns County, Florida

NWS Jacksonville, FL issued this severe thunderstorm warning at Aug 18, 2020, 2:24 PM EDT for Saint Johns County, Florida. It was in force for 51 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
Aug 18, 2020, 2:24 PM EDT (18:24 UTC)
Expired
Aug 18, 2020, 3:15 PM EDT
In force
51 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 18:24 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, 6.4 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-pSkew-T log-p diagram, Jacksonville, FL at 12:00Z on 2020-08-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2385 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 12:00Z on 2020-08-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 17 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
2385 J/kg
Mixed-layer CIN
-40 J/kg
Mixed-layer LCL
825 m above ground
0-6 km bulk shear
9 kt
0-1 km storm-relative helicity
17 m²/s²
0-3 km storm-relative helicity
19 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

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 Aug 18, 1:14 PM EDT, 1 hour 10 minutes earlier.

Area forecast discussion, Aug 18, 1:14 PM EDT, 1 hour 10 minutes before
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In the hours before

Special weather statement, Aug 18, 1:29 PM EDT, 55 minutes before
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Special weather statement, Aug 18, 1:43 PM EDT, 41 minutes before
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Special weather statement, Aug 18, 1:59 PM EDT, 25 minutes before
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Local storm report, Aug 18, 2:14 PM EDT, 10 minutes before
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Special weather statement, Aug 18, 2:18 PM EDT, 6 minutes before
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Local storm report, Aug 18, 2:24 PM EDT, 0 minutes before
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      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
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      <p id="message2">
        Please try again in a few minutes.
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        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
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The office that day

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

IssuedProductOfficeCountiesLasted
Aug 17, 9:37 PM EDTSpecial Weather StatementJAXClay38 min
Aug 17, 10:10 PM EDTAreal Flood WarningJAXBradford, Clay99 min
Aug 18, 1:29 PM EDTSpecial Weather StatementJAXSaint Johns46 min
Aug 18, 1:43 PM EDTSpecial Weather StatementJAXDuval47 min
Aug 18, 1:59 PM EDTSpecial Weather StatementJAXSaint Johns31 min
Aug 18, 2:00 PM EDTSpecial Marine WarningJAX60 min
Aug 18, 2:18 PM EDTSpecial Weather StatementJAXDuval42 min
Aug 18, 2:23 PM EDTSpecial Marine WarningJAX97 min
Aug 18, 2:27 PM EDTSpecial Weather StatementJAXFlagler48 min
Aug 18, 2:34 PM EDTSpecial Weather StatementJAXDuval41 min
Aug 18, 2:57 PM EDTSpecial Weather StatementJAXNassau48 min
Aug 18, 2:58 PM EDTSpecial Marine WarningJAX62 min
Aug 18, 3:19 PM EDTSpecial Weather StatementJAXPutnam56 min
Aug 18, 3:28 PM EDTSpecial Weather StatementJAXFlagler47 min
Aug 18, 3:34 PM EDTSpecial Weather StatementJAXAlachua56 min
Aug 18, 3:39 PM EDTSpecial Weather StatementJAXBradford, Clay66 min
Aug 18, 4:13 PM EDTSpecial Weather StatementJAXPutnam47 min
Aug 18, 4:22 PM EDTSpecial Weather StatementJAXAlachua68 min
Aug 18, 4:41 PM EDTSpecial Weather StatementJAXBradford49 min
Aug 18, 4:56 PM EDTAreal Flood WarningJAXPutnam3 hr
Aug 18, 4:58 PM EDTSevere Thunderstorm WarningJAXAlachua, Putnam47 min
Aug 18, 5:16 PM EDTSpecial Weather StatementJAXPutnam44 min
Aug 18, 5:26 PM EDTAreal Flood WarningJAXBradford3 hr
Aug 18, 5:29 PM EDTSpecial Weather StatementJAXAlachua46 min
Aug 18, 5:46 PM EDTAreal Flood WarningJAXAlachua, Clay, Marion, Putnam3 hr
Aug 18, 5:57 PM EDTSpecial Weather StatementJAXBaker, Columbia, Union48 min
Aug 18, 6:23 PM EDTSpecial Weather StatementJAXHamilton52 min
Aug 18, 6:29 PM EDTSevere Thunderstorm WarningJAXBaker, Columbia46 min
Aug 18, 6:49 PM EDTSpecial Weather StatementJAXColumbia41 min
Aug 18, 7:10 PM EDTSpecial Marine WarningJAX95 min
Aug 18, 7:31 PM EDTSpecial Weather StatementJAXHamilton44 min
Aug 18, 7:46 PM EDTSpecial Weather StatementJAXHamilton59 min
Aug 18, 3:12 PM EDTSpecial Weather StatementJAXCamden48 min
Aug 18, 3:47 PM EDTSpecial Weather StatementJAXCharlton43 min
Aug 18, 4:21 PM EDTSpecial Weather StatementJAXBrantley24 min
Aug 18, 4:32 PM EDTSpecial Weather StatementJAXCharlton28 min
Aug 18, 4:39 PM EDTSpecial Weather StatementJAXClinch36 min
Aug 18, 4:50 PM EDTSpecial Weather StatementJAXBrantley, Pierce40 min
Aug 18, 5:06 PM EDTSpecial Weather StatementJAXAppling, Jeff Davis39 min
Aug 18, 5:09 PM EDTSevere Thunderstorm WarningJAXClinch, Ware51 min
Aug 18, 5:15 PM EDTSpecial Weather StatementJAXBacon30 min
Aug 18, 5:19 PM EDTSpecial Weather StatementJAXClinch41 min
Aug 18, 5:26 PM EDTSpecial Weather StatementJAXClinch34 min
Aug 18, 5:46 PM EDTSpecial Weather StatementJAXAppling, Bacon, Coffee59 min
Aug 18, 5:50 PM EDTSpecial Weather StatementJAXClinch, Ware40 min
Aug 18, 5:57 PM EDTAreal Flood WarningJAXClinch3 hr
Aug 18, 6:10 PM EDTAreal Flood WarningJAXAppling, Jeff Davis3 hr
Aug 18, 6:34 PM EDTSevere Thunderstorm WarningJAXAtkinson, Coffee41 min
Aug 18, 6:43 PM EDTSpecial Weather StatementJAXAppling, Atkinson, Bacon, Coffee, Pierce, Wayne62 min
Aug 18, 6:53 PM EDTAreal Flood WarningJAXAppling, Wayne3 hr
Aug 18, 7:05 PM EDTAreal Flood WarningJAXAtkinson, Coffee3 hr
Aug 18, 7:19 PM EDTSevere Thunderstorm WarningJAXAtkinson, Clinch41 min
Aug 18, 7:24 PM EDTSpecial Weather StatementJAXGlynn51 min
Aug 18, 7:43 PM EDTSpecial Weather StatementJAXAtkinson, Bacon, Pierce62 min

Nearby

Severe Thunderstorm Warnings in Florida, 2020Every 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.