Alert archive / Florida / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 221, NWS Jacksonville, FL

July 17, 2017Duval County, Nassau County, Florida

NWS Jacksonville, FL issued this severe thunderstorm warning at Jul 17, 2017, 3:38 PM EDT for Duval County, Nassau County, Florida. It was in force for 52 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
Jul 17, 2017, 3:38 PM EDT (19:38 UTC)
Expired
Jul 17, 2017, 4:30 PM EDT
In force
52 min
Issued by
NWS Jacksonville, FL
Area
Storm-based polygon
Tornado
Possible
Hail
0.75 in
Wind
60.0 mph

Counties Duval County, FL, Nassau County, FL

The radar

The Jacksonville radar (KJAX), 1 km from the middle of the area, began a volume at 19:42 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, 7.6 hours before the alert went out and 248 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 2017-07-17Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1444 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 2017-07-17The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 46 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
1444 J/kg
Mixed-layer CIN
-16 J/kg
Mixed-layer LCL
757 m above ground
0-6 km bulk shear
9 kt
0-1 km storm-relative helicity
46 m²/s²
0-3 km storm-relative helicity
27 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 Jul 17, 3:28 PM EDT, 10 minutes earlier.

Area forecast discussion, Jul 17, 3:28 PM EDT, 10 minutes before
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Hazardous weather outlook, Jul 17, 3:39 AM EDT, 11 hours 59 minutes before
Hazardous Weather Outlook
National Weather Service Jacksonville FL
339 AM EDT Mon Jul 17 2017

AMZ450-452-454-470-472-474-FLZ020>025-030>033-035>038-040-124-125-
GAZ132>136-149>154-162>166-181015-
Coastal waters from Altamaha Sound to Fernandina Beach FL out
20 NM-
Coastal waters from Fernandina Beach to St. Augustine FL out
20 NM-
Coastal waters from St. Augustine to Flagler Beach FL out 20 NM-
Waters from Altamaha Sound GA to Fernandina Beach FL from 20 to
60 NM-
Waters from Fernandina Beach to St. Augustine FL from 20 to 60 NM-
Waters from St. Augustine to Flagler Beach FL from 20 to 60 NM-
Hamilton-Suwannee-Columbia-Baker-Inland Nassau-Inland Duval-Union-
Bradford-Clay-St. Johns-Gilchrist-Alachua-Putnam-Flagler-Marion-
Coastal Nassau-Coastal Duval-Coffee-Jeff Davis-Bacon-Appling-
Wayne-Atkinson-Ware-Pierce-Brantley-Inland Glynn-Coastal Glynn-
Echols-Clinch-Charlton-Inland Camden-Coastal Camden-
339 AM EDT Mon Jul 17 2017

This Hazardous Weather Outlook is for Northeast Florida,
Southeast Georgia and the Adjacent Coastal Waters.

.DAY ONE...Today and Tonight...

Scattered to numerous thunderstorms are expected to develop this
afternoon and evening. Frequent lighting, heavy rainfall and
localized flooding are the primary hazards. A few storms could
produce strong wind gusts.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday...

Scattered to numerous thunderstorms are expected Tuesday and
Wednesday. Storm coverage will decrease and become more scattered
across the area Thursday through Sunday. Hot temperatures are
expected Thursday through Sunday with highs reaching the mid to
upper 90s inland. Afternoon heat indices will be in the 104 to
109 degree range.

.SPOTTER INFORMATION STATEMENT...

Spotters are asked to self activate this afternoon if warnings
are issued.

For additional information, visit the National Weather Service in
Jacksonville website on the internet at weather.gov/jax.

In the hours before

Special weather statement, Jul 17, 2:57 PM EDT, 41 minutes before
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Special weather statement, Jul 17, 2:59 PM EDT, 39 minutes before
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Special weather statement, Jul 17, 3:04 PM EDT, 34 minutes before
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Local storm report, Jul 17, 3:10 PM EDT, 28 minutes before
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Special weather statement, Jul 17, 3:10 PM EDT, 28 minutes before
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Special weather statement, Jul 17, 3:31 PM EDT, 7 minutes before
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The office that day

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

IssuedProductOfficeCountiesLasted
Jul 17, 12:26 PM EDTSpecial Weather StatementJAXColumbia34 min
Jul 17, 1:13 PM EDTSpecial Weather StatementJAXColumbia32 min
Jul 17, 1:39 PM EDTSpecial Weather StatementJAXDuval36 min
Jul 17, 1:59 PM EDTSpecial Weather StatementJAXSaint Johns46 min
Jul 17, 2:03 PM EDTSpecial Weather StatementJAXSaint Johns42 min
Jul 17, 2:05 PM EDTSpecial Weather StatementJAXAlachua40 min
Jul 17, 2:18 PM EDTSevere Thunderstorm WarningJAXAlachua, Bradford42 min
Jul 17, 2:28 PM EDTSevere Thunderstorm WarningJAXSaint Johns30 min
Jul 17, 2:30 PM EDTSpecial Weather StatementJAXMarion45 min
Jul 17, 2:39 PM EDTSpecial Weather StatementJAXPutnam51 min
Jul 17, 2:44 PM EDTAreal Flood AdvisoryJAXAlachua91 min
Jul 17, 2:46 PM EDTSpecial Weather StatementJAXBradford, Clay44 min
Jul 17, 2:54 PM EDTAreal Flood AdvisoryJAXPutnam96 min
Jul 17, 2:57 PM EDTSpecial Weather StatementJAXDuval48 min
Jul 17, 2:59 PM EDTSpecial Weather StatementJAXSaint Johns46 min
Jul 17, 3:04 PM EDTSpecial Weather StatementJAXMarion41 min
Jul 17, 3:18 PM EDTSevere Thunderstorm WarningJAXFlagler, Saint Johns27 min
Jul 17, 3:24 PM EDTSevere Thunderstorm WarningJAXClay, Duval36 min
Jul 17, 3:27 PM EDTSpecial Marine WarningJAX63 min
Jul 17, 3:31 PM EDTSpecial Weather StatementJAXNassau44 min
Jul 17, 3:40 PM EDTAreal Flood AdvisoryJAXClay, Duval95 min
Jul 17, 3:45 PM EDTSevere Thunderstorm WarningJAXFlagler17 min
Jul 17, 3:49 PM EDTSpecial Weather StatementJAXPutnam41 min
Jul 17, 3:57 PM EDTAreal Flood AdvisoryJAXDuval, Nassau93 min
Jul 17, 4:01 PM EDTSpecial Weather StatementJAXNassau44 min
Jul 17, 4:06 PM EDTSevere Thunderstorm WarningJAXNassau39 min
Jul 17, 4:10 PM EDTSpecial Weather StatementJAXFlagler50 min
Jul 17, 4:38 PM EDTSpecial Weather StatementJAXFlagler52 min
Jul 17, 4:42 PM EDTSpecial Marine WarningJAX63 min
Jul 17, 4:51 PM EDTSevere Thunderstorm WarningJAXFlagler39 min
Jul 17, 1:44 PM EDTSpecial Weather StatementJAXAtkinson46 min
Jul 17, 2:11 PM EDTSpecial Weather StatementJAXClinch49 min
Jul 17, 2:44 PM EDTSpecial Weather StatementJAXCharlton, Ware46 min
Jul 17, 3:10 PM EDTSpecial Weather StatementJAXBrantley, Pierce50 min
Jul 17, 3:54 PM EDTSpecial Weather StatementJAXBrantley, Wayne51 min
Jul 17, 4:40 PM EDTSpecial Weather StatementJAXGlynn50 min

Nearby

Severe Thunderstorm Warnings in Florida, 2017Every severe thunderstorm warning in 2017

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.