A dominant east coast sea breeze fired convection as it drifted inland toward the I-75 corridor. Elevated moisture content supported locally heavy rainfall and wet downburst potential.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS JAX wrote it up.
A dominant east coast sea breeze fired convection as it drifted inland toward the I-75 corridor. Elevated moisture content supported locally heavy rainfall and wet downburst potential.
The local office's own words before the first event, 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 the first event at Aug 20, 1:41 PM EST, 49 minutes earlier.
Area Forecast Discussion National Weather Service Jacksonville FL 241 PM EDT Sun Aug 20 2017 .NEAR TERM /Through Monday/... Another hot August day was observed across the region with temperatures in the low to mid 90s. Only widely scattered showers and storms have developed thus far this afternoon due to the subsidence aloft and the slow progression of the east coast sea breeze. Expect scattered to numerous showers and storms to develop across the interior in the moisture tongue that exists from west of St. Simons to the Suwannee Valley. A few strong storms with gusty winds and small hail are possible. Scattered showers/storms will remain along the Suwannee Valley towards I-75 in the evening, dissipating a few hours after sunset. As a trough approaches the region tonight, shower chances will increase along the coast overnight. Overnight lows will be in the 70s. Upper level low over the south central Gulf of Mexico will shift to the western Gulf on Monday. An +PV anomaly associated with an inverted trough/wave was located from south central Florida northeastward into the western Atlantic. This feature shows up well on satellite, with significant cloud across southern and central Florida, and to the east of the region this afternoon. The trough will slide north to northwestward tonight and Monday, moving to the northeast Florida coastline by Monday morning. A strong upper level ridge across the western Atlantic will build across Georgia and the Southeast on Monday. A vort max associated with the inverted trough over south central Florida this afternoon will move over northeast Florida on Monday, and this will bring deep moisture to the area, with precipitable water values above 2 inches. In addition, increasing cloud cover and rainfall chances are expected along the coast late tonight into Monday morning. Scattered showers and storms will then move inland through the day as the wave axis shifts across the interior. Mostly cloudy skies are expected across the southeastern half of the region Monday morning, with clouds spreading inland as the trough moves to the northwest. The best viewing locations for the eclipse on Monday are northwest of Alma and possibly along the coast in northeast Florida to the east of I-95 as the wave axis pushes across the interior and a weak east coast sea breeze moves inland. Otherwise, mostly cloudy skies will prevail through the day with scattered showers and storms. Temperatures are forecast to be lower on Monday due to cloud cover and scattered showers/storms, with highs in the upper 80s to lower 90s. .SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/... MONDAY NIGHT...There will some drier air with precipitable water values 1.30 to 1.60 inches working its way into north central Florida early Monday evening, in the wake of exiting trof axis that moves into the Gulf of Mexico. However, moisture rich atmosphere will exist between just south of I-10 corridor to just north of Georgia Highway 82. Between this defined area and mainly along and west of highway 301 some residual and ongoing convection is most anticipated during the evening hours, then lifting northward mainly north of the FL/GA border during the late evening through a couple hours past midnight, before everything abating during the pre-dawn hours. TUESDAY AND TUESDAY NIGHT...Tuesday will feature a drier day particularly south of I-10. Upper level ridge centered across the Southeast, and onshore flow continues as surface high pressure moves further north across the mid Atlantic. 30-40% POPS are across the region where there will be lingering shortwave energy may remain with remnant weak surface trof just north of the Altamaha River Basin. The thunderstorm chances should diminish pretty rapidly Tuesday night with the loss of heating and upper ridging extending from the offshore Atlantic through the region into the NE Gulf of Mexico. .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... A cold front will approach the Altamaha River Basin Wednesday morning and reside near the FL/GA midday with pre-frontal trof near I-10 during the afternoon. Strong heating and convergence into a prefrontal trough supports thunderstorms mainly in the afternoon. Consensus models and Superblend have pops 30 to 50 percent. The thunderstorm chance will continue Wednesday night and Thursday with the front in the area. It looks to be drier with the front just off the coast Friday and Saturday, but confidence is low with the front lingering not far to the east. Best chances of rain will mainly be over NE Florida particularly over the eastern sections. A more consolidated tropical low may eventually form along the remnant boundary across the east-central FL coast Friday morning and shift east then NE over the open Atlantic late Friday through Saturday. Temperatures should remain above normal ahead of the front through Wednesday. Expect maximum heat index readings 100 to 105 Wednesday afternoon. The GFS and ECMWF MOS support near normal temperatures Thursday through Saturday. && .AVIATION... An isolated shower moved over KCRG around 18Z, and an isolated storm moved north of KJAX along the east coast sea breeze. Showers/storms will develop and push inland this afternoon. Best chance for shower/storms later this afternoon will be at KVQQ and KGNV. East to southeast winds 5-10 knots will prevail this afternoon. Mid/high clouds will increase overnight as a trough moves towards the region, and showers are possible along the coast late overnight into Monday morning. Have VCSH from late tonight through the end of the TAF period with increasing cloud cover. && .MARINE... Surface ridge axis will continue to shift north of the area resulting in an easterly flow. The surface ridge will remain northeast of the region through Tuesday. A frontal boundary will then shift into the southeast by the middle of the week and the ridge will shift back to the south. Rip Currents: Low risk today, and Low to Moderate risk of rip currents on Monday. && .PRELIMINARY POINT TEMPS/POPS... AMG 75 91 74 92 / 10 30 20 30 SSI 78 87 78 89 / 40 50 20 20 JAX 76 89 75 91 / 30 40 20 10 SGJ 75 88 77 89 / 30 40 10 10 GNV 73 90 74 93 / 20 40 10 20 OCF 74 91 74 93 / 10 30 10 20 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. && Kennedy/Cordero/McGinnis
Hazardous Weather Outlook National Weather Service Jacksonville FL 302 AM EDT Sun Aug 20 2017 AMZ450-452-454-470-472-474-FLZ020>025-030>033-035>038-040-124-125- GAZ132>136-149>154-162>166-211000- 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- 302 AM EDT Sun Aug 20 2017 This Hazardous Weather Outlook is for Northeast Florida, Southeast Georgia and the Adjacent Coastal Waters. .DAY ONE...Today and Tonight... Scattered showers and thunderstorms will develop and shift inland this afternoon. Areas of locally heavy rainfall are possible. .DAYS TWO THROUGH SEVEN...Monday through Saturday... Scattered afternoon and evening thunderstorms are expected Monday through Wednesday. Storms are expected to be more numerous Thursday through Saturday. A few strong thunderstorms are possible each day, with gusty winds, frequent lightning strikes, and heavy downpours. .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.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE JACKSONVILLE FL
1005 AM EDT SUN AUG 20 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0737 PM TSTM WND DMG 5 SSE SANDERSON 30.19N 82.25W
08/19/2017 BAKER FL 911 CALL CENTER
911 CALL CENTER REPORTED A TREE DOWN ON
POWER LINES NEAR RICHARDSON ROAD AND CLET
HARVEY ROAD.
0735 PM TSTM WND DMG 1 ESE MACCLENNY 30.28N 82.12W
08/19/2017 BAKER FL 911 CALL CENTER
911 CALL CENTER REPORTED POWER LINES DOWN ON
SOUTH BLVD EAST. TIME ESTIMATED USING RADAR
DATA.
0728 PM TSTM WND DMG 3 WSW GLEN SAINT MARY 30.25N 82.21W
08/19/2017 BAKER FL 911 CALL CENTER
911 CALL CENTER REPORTED TREE DOWN NEAR FRED
PERRY ROAD AND REID STAFFORD ROAD. TIME
ESTIMATED USING RADAR DATA.
&&Special Weather Statement
National Weather Service Jacksonville FL
300 PM EDT SUN AUG 20 2017
FLZ025-032-125-201930-
Inland Duval FL-Clay FL-Coastal Duval FL-
300 PM EDT SUN AUG 20 2017
...SIGNIFICANT WEATHER ADVISORY FOR NORTH CENTRAL CLAY AND SOUTH
CENTRAL DUVAL COUNTIES UNTIL 330 PM EDT...
At 300 PM EDT, Doppler radar was tracking a strong thunderstorm over
San Marco, or near Jacksonville. This storm was nearly stationary.
Wind gusts of 35 to 50 mph can be expected along with possible minor
wind damage.
Locations impacted include...
Jacksonville, Orange Park, Mandarin, Nas Jax, Bellair-Meadowbrook
Terrace, Riverside, San Marco, Ortega and Lakeside.
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 3012 8159 3013 8160 3012 8166 3014 8177
3033 8168 3032 8158 3012 8156
TIME...MOT...LOC 1900Z 053DEG 2KT 3029 8164
ENYEDISpecial Weather Statement
National Weather Service Jacksonville FL
305 PM EDT SUN AUG 20 2017
GAZ136-153-201945-
Inland Glynn GA-Wayne GA-
305 PM EDT SUN AUG 20 2017
...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN GLYNN AND
SOUTHEASTERN WAYNE COUNTIES UNTIL 345 PM EDT...
At 304 PM EDT, Doppler radar was tracking a strong thunderstorm over
Cox, or 9 miles northwest of Darien, moving southwest at 10 mph.
Nickel size hail and wind gusts of 35 to 50 mph can be expected
along with possible minor damage.
Locations impacted include...
Everett and Mount Pleasant.
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 3128 8160 3140 8177 3150 8165 3149 8164
3149 8162 3147 8161 3145 8163 3144 8161
3143 8161 3139 8157 3139 8156 3138 8155
3138 8154 3136 8153
TIME...MOT...LOC 1904Z 028DEG 7KT 3145 8157
ENYEDIPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE JACKSONVILLE FL
320 PM EDT SUN AUG 20 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0257 PM TSTM WND GST 5 NNW MANDARIN 30.22N 81.68W
08/20/2017 M41 MPH DUVAL FL ASOS
41 MPH WIND GUST MEASURED AT NAS JACKSONVILLE.
&&
WCORLESSSpecial Weather Statement
National Weather Service Jacksonville FL
329 PM EDT SUN AUG 20 2017
FLZ023>025-202000-
Inland Duval FL-Baker FL-Inland Nassau FL-
329 PM EDT SUN AUG 20 2017
...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN NASSAU...EAST
CENTRAL BAKER AND WEST CENTRAL DUVAL COUNTIES UNTIL 400 PM EDT...
At 329 PM EDT, Doppler radar was tracking a strong thunderstorm near
Cecil Field, or 15 miles north of Middleburg. This storm was nearly
stationary.
Nickel size hail and wind gusts of 35 to 50 mph can be expected
along with possible minor damage.
Locations impacted include...
Baldwin.
LAT...LON 3022 8190 3027 8210 3037 8205 3037 8204
3039 8204 3040 8203 3031 8185
TIME...MOT...LOC 1929Z 106DEG 3KT 3027 8194
ENYEDIThe Jacksonville radar (KJAX), 40 km away, was scanning. The volume nearest the first event began at 19:30 UTC.
1 thunderstorm wind, 1 flood. Local standard time, as filed.
Power lines were blown down near Hood Landing Road, south of Julington Creek Road. The time of damage was based on radar imagery. The cost of damage was unknown, but it was estimated so the event could be included in Storm Data.
The southbound lane of State Road 21 was closed near the Intersection of Baden Powell Road due to flooding.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Florida in 2017Every state in 2017This day in weather historyWarnings in Florida, August 2017
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 711586, 711585.