Alert archive / Florida / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 277, NWS Jacksonville, FL

August 31, 2017Clay County, Putnam County, Saint Johns County, Florida

NWS Jacksonville, FL issued this severe thunderstorm warning at Aug 31, 2017, 6:43 PM EDT for Clay County, Putnam County, Saint Johns County, Florida. It was in force for 32 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 31, 2017, 6:43 PM EDT (22:43 UTC)
Expired
Aug 31, 2017, 7:15 PM EDT
In force
32 min
Issued by
NWS Jacksonville, FL
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

Counties Clay County, FL, Putnam County, FL, Saint Johns County, FL

The radar

The Jacksonville radar (KJAX), 72 km from the middle of the area, began a volume at 22:43 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, 10.7 hours before the alert went out and 74 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 2017-08-31Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1403 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 2017-08-31The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 49 square meters per square second.193958Sfc1 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
1403 J/kg
Mixed-layer CIN
-24 J/kg
Mixed-layer LCL
744 m above ground
0-6 km bulk shear
25 kt
0-1 km storm-relative helicity
49 m²/s²
0-3 km storm-relative helicity
72 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.4

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 31, 3:09 PM EDT, 3 hours 34 minutes earlier.

Area forecast discussion, Aug 31, 3:09 PM EDT, 3 hours 34 minutes before
Area Forecast Discussion
National Weather Service Jacksonville FL
309 PM EDT Thu Aug 31 2017

...Isolated Severe Storms Today and Friday, mainly across
Southeast Georgia...

.NEAR TERM /Tonight-Friday/...

Rest of this Afternoon/Evening...Broken squall line with strong
storms and isolated severe storms expected to cross through inland
SE GA with the best threat of Severe Storms mainly North and West
of Waycross. The line is expected to weaken early this evening but
may still see some strong storms closer to the I-95 and US-301
corridors as remaining storms/outflows collide with Atlc Coast Sea
Breeze front pushing inland. These storms will continue until late
evening then fade around midnight as they push into the Atlc
Ocean. Main threat this evening is damaging winds across inland SE
GA but strong gusty winds are possible in any storm activity.
Isolated Large Hail or a tornado cannot be ruled out in bowing
segments...mainly across SE GA or in sea breeze/storm
interactions. Locally heavy rainfall possible across SE GA as
training of cells possible but antecedent conditions relatively
drier so not expecting significant flooding threat.

Overnight...Diurnal activity basically ends by midnight with fair
skies/convective debris clouds and partly cloudy skies although
the strong SW steering flow could produce some storm activity
across the Big Bend region of the NE Gomex that could trickle into
the I-75 corridor of inland North Florida towards morning but
should be weakening and isolated the further it tracks inland.
Muggy overnight lows in the mid/upper 70s expected.

Friday...Band of deeper moisture in the SW steering flow steps
just a bit further Eastward and is located from the Big Bend
region across North Florida and SE GA. This will set up slightly
better chances of rainfall area-wide with Pops generally 50-70%
and with moisture source much closer, expect an earlier start to
convection during the late morning hours as it won't take as much
heating to kick off convection with PWATS much closer to 2 inches.
The earlier start to convection will hold max temps closer to 90
degrees with heat indices in the 100-105 range. The strong belt of
SW winds aloft will still support scattered strong and isolated
severe storms with main threat of strong/damaging winds in a few
storms. Also the higher PWATs will support a better chance of
locally heavy rainfall, especially if some of the SW-NE oriented
bands don't have enough Eastward translation during peak heating
tomorrow and will need to watch for minor/localized flooding from
isolated areas that pick up a quick 2-3 inches of rainfall.

.SHORT TERM...Friday night through Sunday night...Trailing moisture
axis associated with remnants of Harvey will still be across se
Ga/ne Fl on Saturday. Daytime heating and a moderate sw flow with
adequate shear will likely mean another round of strong to severe
storms Saturday aftn/eve. Troughing aloft will lift to the ne on
Sunday which will mean lighter winds and less shear for our area.
Storms will be more scattered with best coverage over inland areas
near the seabreeze collision. Temperatures will be near average with
above average pops Saturday and near average Sunday.

.LONG TERM...Monday through Thursday...A lighter sw flow will be
across the area Monday and Tuesday with a mid-upper level ridge
building across s Fl. Moisture will still be abundant so expect
scattered diurnal seabreeze storms with best coverage over inland
areas. Upper trough amplifies over the eastern U.S. Wednesday into
Thursday which will push a cold front into the area on Thursday.
GFS/GEFS continues to be more aggresive moving this system eastward
than the ECMWF. Storms should become numerous Wednesday into
Thursday for parts of the area with either solution. Temperatures
will be be close to average through the period. Pops will be near
average Monday and Tuesday...and at or above average Wednesday and
Thursday.

&&

.AVIATION...
Still expecting a few scattered showers/storms to impact the TAF
sites in the 21z-01z time frame and have upped to VCTS at all TAF
sites and may need to add TEMPO groups if the broken squall line
reaches all the way to the I-95 corridor/TAF sites. Some gusty
winds to 30-40 knots and MVFR CIGS/VSBYS are possible if the line
holds together.

&&

.MARINE...
South to Southwest flow will continue at 10-15 knots with seas 2-5
ft and no headlines into the weekend. Main impacts will be
offshore moving storms Today-Friday with gusty winds possible.
Weak frontal boundary/wind shift will be possible late in the
weekend and early next week with winds becoming more light and
variable at 10 knots or less and seas 1-3 ft or less from Sunday
through Tuesday.

Rip Currents: Moderate Risk continues in the lingering onshore
swell.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  74  90  73  88 /  20  40  20  60
SSI  78  89  77  85 /  40  60  40  60
JAX  76  92  75  88 /  40  50  30  50
SGJ  77  91  76  87 /  40  70  30  50
GNV  75  91  74  87 /  30  50  30  50
OCF  75  91  74  88 /  30  70  30  50

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AM...None.
&&

Hess/Zibura/McGinnis
Hazardous weather outlook, Aug 31, 1:45 PM EDT, 4 hours 58 minutes before
Hazardous Weather Outlook
National Weather Service Jacksonville FL
145 PM EDT Thu Aug 31 2017

AMZ450-452-454-470-472-474-FLZ020>025-030>033-035>038-040-124-125-
GAZ132>136-149>154-162>166-010745-
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-
145 PM EDT Thu Aug 31 2017

...SLIGHT RISK OF SEVERE STORMS ACROSS SOUTHEAST GEORGIA TODAY...

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

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

Heat indices 102 to 107 degrees across northeast Florida.

Moderate risk of rip currents.

Chance for afternoon and evening thunderstorms, especially across
southeast Georgia and eastern half of northeast Florida. A slight
risk of severe storms is possible across Southeast Georgia with
damaging winds the main threat although locally heavy rainfall, hail
and an isolated tornado is possible. Strong storms will be possible
across Northeast Florida and capable of producing gusty winds,
frequent lightning and locally heavy rainfall.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday...

Scattered to numerous mainly afternoon thunderstorms each day
capable of producing gusty winds and locally heavy rainfall.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.

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, Aug 31, 6:04 PM EDT, 39 minutes before
Special Weather Statement
National Weather Service Jacksonville FL
604 PM EDT THU AUG 31 2017

FLZ025-033-125-312230-
Inland Duval FL-St. Johns FL-Coastal Duval FL-
604 PM EDT THU AUG 31 2017

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN ST. JOHNS AND
SOUTHEASTERN DUVAL COUNTIES UNTIL 630 PM EDT...

At 604 PM EDT, Doppler radar was tracking a strong thunderstorm over
Switzerland, or over Fruit Cove, moving northeast at 20 mph.

Excessive cloud-to-ground lightning and wind gusts up to 45 mph can
be expected.

Locations impacted include...
Unf, Fruit Cove, Baymeadows, Nocatee, Bayard and Durbin.

LAT...LON 2998 8163 3000 8165 3028 8158 3028 8144
      3004 8143
TIME...MOT...LOC 2204Z 238DEG 15KT 3008 8164

ELSENHEIMER
Special weather statement, Aug 31, 6:06 PM EDT, 37 minutes before
Special Weather Statement
National Weather Service Jacksonville FL
606 PM EDT THU AUG 31 2017

GAZ136-152-153-312230-
Inland Glynn GA-Brantley GA-Wayne GA-
606 PM EDT THU AUG 31 2017

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN GLYNN...NORTHEASTERN
BRANTLEY AND SOUTHERN WAYNE COUNTIES UNTIL 630 PM EDT...

At 605 PM EDT, Doppler radar was tracking a strong thunderstorm near
Raybon, or 10 miles northeast of Nahunta, moving northeast at 40 mph.

Excessive cloud-to-ground lightning and wind gusts of 45 to 55 mph
can be expected along with possible minor damage.

Locations impacted include...
Gardi, Everett, Broadhurst, Mount Pleasant and Hortense.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 3158 8170 3156 8170 3154 8168 3154 8167
      3153 8167 3153 8165 3151 8166 3149 8164
      3148 8162 3147 8161 3145 8163 3144 8161
      3143 8161 3137 8154 3127 8199 3131 8199
      3131 8201 3143 8205 3159 8172
TIME...MOT...LOC 2205Z 244DEG 34KT 3134 8190

NELSON
Special weather statement, Aug 31, 6:11 PM EDT, 32 minutes before
Special Weather Statement
National Weather Service Jacksonville FL
611 PM EDT THU AUG 31 2017

GAZ164>166-312300-
Inland Camden GA-Charlton GA-Coastal Camden GA-
611 PM EDT THU AUG 31 2017

...SIGNIFICANT WEATHER ADVISORY FOR CAMDEN AND NORTHEASTERN CHARLTON
COUNTIES UNTIL 700 PM EDT...

At 611 PM EDT, Doppler radar was tracking a strong thunderstorm near
Kings Ferry, or 7 miles northwest of Kingsland, moving northeast at
20 mph.

Excessive cloud-to-ground lightning and wind gusts of 40 to 50 mph
can be expected along with possible minor damage.

Locations impacted include...
Kingsland, Woodbine, Homeland, Tarboro, Cumberland Island, Harrietts
Bluff and Colesburg.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 3083 8142 3075 8173 3078 8177 3077 8177
      3079 8179 3078 8180 3079 8181 3079 8184
      3083 8190 3082 8191 3089 8208 3110 8189
      3110 8184 3113 8182 3088 8141
TIME...MOT...LOC 2211Z 246DEG 18KT 3085 8177

NELSON
Special weather statement, Aug 31, 6:21 PM EDT, 22 minutes before
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Special weather statement, Aug 31, 6:32 PM EDT, 11 minutes before
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Special weather statement, Aug 31, 6:35 PM EDT, 8 minutes before
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    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
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        The site you requested is temporarily down for maintenance or an unexpected outage.
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The office that day

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

IssuedProductOfficeCountiesLasted
Aug 30, 8:13 PM EDTSpecial Weather StatementJAXPutnam32 min
Aug 31, 3:09 PM EDTSpecial Weather StatementJAXMarion51 min
Aug 31, 3:17 PM EDTSpecial Weather StatementJAXAlachua43 min
Aug 31, 4:04 PM EDTSpecial Weather StatementJAXAlachua41 min
Aug 31, 4:18 PM EDTAreal Flood AdvisoryJAXAlachua, Marion57 min
Aug 31, 4:52 PM EDTSpecial Weather StatementJAXMarion23 min
Aug 31, 5:30 PM EDTSpecial Weather StatementJAXClay45 min
Aug 31, 5:44 PM EDTSpecial Weather StatementJAXDuval, Nassau31 min
Aug 31, 6:04 PM EDTSpecial Weather StatementJAXDuval26 min
Aug 31, 6:14 PM EDTAreal Flood AdvisoryJAXClay, Duval, Saint Johns91 min
Aug 31, 6:21 PM EDTSpecial Weather StatementJAXSaint Johns39 min
Aug 31, 7:16 PM EDTSpecial Weather StatementJAXSaint Johns29 min
Aug 31, 7:18 PM EDTSpecial Marine WarningJAX87 min
Aug 31, 3:20 PM EDTSpecial Weather StatementJAXCoffee40 min
Aug 31, 3:57 PM EDTSpecial Weather StatementJAXCoffee, Jeff Davis48 min
Aug 31, 4:24 PM EDTSpecial Weather StatementJAXAppling51 min
Aug 31, 4:35 PM EDTSpecial Weather StatementJAXAppling, Bacon40 min
Aug 31, 4:48 PM EDTSpecial Weather StatementJAXPierce42 min
Aug 31, 4:52 PM EDTSevere Thunderstorm WarningJAXBacon17 min
Aug 31, 4:58 PM EDTSpecial Weather StatementJAXAppling32 min
Aug 31, 5:23 PM EDTSpecial Weather StatementJAXWayne52 min
Aug 31, 5:41 PM EDTSpecial Weather StatementJAXPierce34 min
Aug 31, 6:06 PM EDTSpecial Weather StatementJAXWayne24 min
Aug 31, 6:11 PM EDTSpecial Weather StatementJAXCamden49 min
Aug 31, 6:32 PM EDTSpecial Weather StatementJAXGlynn28 min
Aug 31, 6:35 PM EDTSpecial Weather StatementJAXBrantley25 min
Aug 31, 6:50 PM EDTSevere Thunderstorm WarningJAXGlynn, Wayne25 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.