The first strong onshore flow event of the season developed between strong high pressure building across the Mid-West toward New England and a frontal boundary SE of the area. Winds increased through the day as the pressure gradient strengthened.
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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.
The first strong onshore flow event of the season developed between strong high pressure building across the Mid-West toward New England and a frontal boundary SE of the area. Winds increased through the day as the pressure gradient strengthened. Sustained gradient winds and wind gusts were between 20-30 mph with gusts 30-40 mph, and a Wind Advisory was in effect for coastal counties. Waves of locally heavy rainfall moved onshore. A coastal flood warning was in place due to the stronger NE wind surge combining with seasonally high King Tides. Some areas with poor drainage and tidal estuaries had exacerbated flooding issues due to elevated tidal levels.
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 Sep 18, 6:28 PM EST, 4 hours 32 minutes earlier.
Area Forecast Discussion
National Weather Service Jacksonville FL
728 PM EDT Fri Sep 18 2020
.NEAR TERM [Through Tonight]...
The northeast flow pattern will intensify Tonight as high pressure
builds to the north, and an inverted trough builds over the western
Atlantic. Cloud coverage will increase through the night, as
isolated to scattered showers become more common. The best chance
for these showers will be along the coastal counties. Winds will
pick up overnight along the coast, becoming noticeably gusty at
area beaches by dawn. The showers that come ashore overnight will
also produce briefly higher wind gusts. Lows will generally be in
the upper 60s to around 70 inland, and in the lower to middle 70s
coastal.
&&
.AVIATION...
[Through 00Z Sunday]
Restrictions in stratus will prevail through this period. A few
sprinkles or a brief shower will be possible Tonight. Chances will
increase for rain through the day Saturday.
&&
.PREV DISCUSSION [508 PM EDT]...
.SHORT TERM [Saturday Through Sunday Night]...
Expansive high pressure will strengthen as it shifts west from
the Great Lakes region to New England. This will enhance the
northeasterly flow across the region, leading to breezy to gusty
conditions across the area; coastal areas will be on gustier side
with respect to gradient winds. Additionally, scattered to
numerous showers and isolated storms are expected to move onshore,
primarily affecting the coastal areas, each afternoon.
Northeasterly steering flow may result in multiple waves of heavy
rain along the northeast Florida coast/beaches this
weekend...localized flooding will be a concern.
As a drier, cooler airmass upstream slowly jostles its way south,
a noticeable plunge in temps will occur, with readings between
8-10 degrees below mid-September normals. By Sunday, high temps
across most of the area will be in the low to upper 70s with
morning low falling into the low to mid 60s across southeast
Georgia and the upper 60s to lower 70s across northeast Florida.
.LONG TERM [Monday Through Friday]...
Surface high will remain centered over New England through
Monday before repositioning and stacking under broad ridging
aloft. Prolonged strong northeasterly winds (and associated
coastal hazards) will likely remain through Monday but may start
to back off on Tuesday as winds veer to the east as the surface
high scoots to the southeast. Meanwhile, dry north-northeasterly
low to mid-level flow will scour moisture to our south, eliminating
chances for most of the area with the exception of low-end chances
along the coastal northeast Florida. Shower and storm chances
will remain at bay through at least Wednesday before the influence
of TS Beta lift a tropical airmass northward back over the area on
Thursday. Unseasonably cool, Fall-like temps will continue
through the middle of next week before trending back towards
normal.
.MARINE...
High pressure will strengthen over the Great Lakes through this
evening and will wedge into the southeastern states tomorrow,
with an abrupt north to northeasterly wind surge entering the
southeast Georgia waters just after midnight tonight and then
overspreading the northeast Florida waters during the predawn and
early morning hours on Saturday. Have posted a Gale Watch to
replace small craft advisories by late morning Saturday into
Monday as well as a high surf advisory for surf heights increasing
to 6 to 9 feet along the coast. Strong high pressure will then
build over New England tomorrow night and Sunday, maintaining
strong northeasterly winds across our waters through Monday night,
with widespread showers and a few thunderstorms expected. High
pressure will then weaken over the Appalachians on Tuesday as a
Tropical Cyclone approaches Deep South Texas.
Rip Currents: High Risk of Rip currents through Monday for NE FL
and SE GA due to the NE winds surging onshore through the weekend.
.HYDROLOGY...
The strong NE onshore flow will push bands of showers and isolated
storms into the St Johns and Flagler coastal areas on Saturday
and Sunday with rainfall totals of 2-3 inches expected. Localized
flooding is expected which will be exacerbated during times of
high tide along the coast and in urban areas. However, a flash
flood watch does not appear needed at this time.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 67 77 61 76 57 / 0 10 10 0 0
SSI 73 79 68 78 66 / 30 30 20 10 10
JAX 71 79 69 79 68 / 40 60 30 30 10
SGJ 74 82 73 82 72 / 50 80 50 50 20
GNV 70 83 69 79 67 / 10 60 20 30 10
OCF 71 86 71 83 69 / 10 70 20 30 10
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...High Rip Current Risk from 6 AM EDT Saturday through Monday
afternoon for Coastal Duval-Coastal Flagler-Coastal Nassau-
Coastal St. Johns.
Coastal Flood Watch from Saturday evening through Monday
afternoon for Coastal Duval-Coastal Flagler-Coastal Nassau-
Coastal St. Johns.
High Surf Advisory from 5 PM Saturday to 6 PM EDT Monday for
Coastal Duval-Coastal Flagler-Coastal Nassau-Coastal St.
Johns.
Coastal Flood Advisory from 9 AM to 8 PM EDT Saturday for
Coastal Duval-Coastal Flagler-Coastal Nassau-Coastal St.
Johns.
Coastal Flood Advisory from 9 AM Saturday to 6 PM EDT Monday for
Clay-Inland Duval-Inland Flagler-Inland St. Johns-Putnam.
GA...High Rip Current Risk from 6 AM EDT Saturday through Monday
afternoon for Coastal Camden-Coastal Glynn.
Coastal Flood Watch from Saturday evening through Monday
afternoon for Coastal Camden-Coastal Glynn.
High Surf Advisory from 5 PM Saturday to 6 PM EDT Monday for
Coastal Camden-Coastal Glynn.
Coastal Flood Advisory from 9 AM to 8 PM EDT Saturday for
Coastal Camden-Coastal Glynn.
AM...Gale Watch from Saturday morning through Monday afternoon for
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.
Small Craft Advisory from 4 AM to 10 AM EDT Saturday for 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 Fernandina Beach to St. Augustine FL from
20 to 60 NM-Waters from St. Augustine to Flagler Beach FL
from 20 to 60 NM.
Small Craft Advisory from midnight tonight to 10 AM EDT Saturday
for Coastal waters from Altamaha Sound to Fernandina Beach
FL out 20 NM-Waters from Altamaha Sound GA to Fernandina
Beach FL from 20 to 60 NM.
&&The national radar mosaic for the moment the first event began.
4 heavy rain, 2 coastal flood, 1 high wind. Local standard time, as filed.
As of 1518, a public weather station measured a daily rainfall of 4.63 off of Cypress Links Blvd.
As of 1518, a public weather station off of Sierras Loop measured a daily rainfall of 4.92 inches.
Storm total rainfall from Bulowville as of 2000 was 3.85 inches.
Storm total rainfall as of 2050 was 4 inches.
King Street was closed due to tidal flooding in Historic St. Augustine near the Bridge of Lions to Malaga Street near the San Sebastian River.
Most sea walls in Flagler County, including in Palm Coast, were over-topped by elevated tidal levels. Around 1500, Bings Landing near Matanzas Inlet measured a high tide of 1.86 ft MHHW datum which was in the moderate flood category.
A strong local NE flow produced wind gusts around 40 mph at the Marineland mesonet site around the time power lines were blown down onto Palm Coast along Atlantic Drive near the Hammocks. The cost of damage was estimated.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Florida in 2020Every state in 2020This day in weather historyWarnings in Florida, September 2020
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: 921586, 921587, 921588, 921590, 921592, 921591, 921593.