High moisture content and stronger onshore easterly flow focused the afternoon sea breeze mergers toward the I-75 corridor in the afternoon and evening, which locally heavy rainfall and gusty winds occurred in storms.
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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.
High moisture content and stronger onshore easterly flow focused the afternoon sea breeze mergers toward the I-75 corridor in the afternoon and evening, which locally heavy rainfall and gusty winds occurred in storms.
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 10, 12:28 PM EST, 42 minutes earlier.
Area Forecast Discussion National Weather Service Jacksonville FL 128 PM EDT Thu Sep 10 2020 .AVIATION... [Through 18Z Friday] Line of showers/isolated storms along the East Coast/Atlc sea breeze front has already pushed west of most of the TAF sites except for a brief TEMPO for a storm possible until 19z at VQQ and until 20Z at GNV, then warm and humid atmosphere will support some VCSH at all TAF sites through 00-01z time frame. Some brief MVFR CIGS will be most common at SGJ, but will be possible at any TAF sites this afternoon until sunset. Mainly VFR with light winds at most TAF sites with onshore flow weakening enough to leave out VCSH for most of the night, some patchy MVFR VSBYS will be possible at GNV/VQQ in the 08-12z time frame, along with possible IFR CIGS but have kept out the low CIGS for now due to uncertainty since last nights low clouds/fog at GNV were due to heavy rainfall at the airport location. On Friday from 12Z-14Z showers will develop once again along the coast and push inland with the east flow pattern and have included VCSH at all TAF sites for now. && .PREV DISCUSSION [958 AM EDT]... .NEAR TERM [Through Friday]... Low stratus ceilings and patches of locally dense fog will be possible through the early morning hours over the Suwannee Valley and much of inland southeast GA. Otherwise, convergent southeasterly flow to the east of the inverted trough axis will continue to generate scattered convection along the I-95 corridor and the coastal waters this morning, with activity then blossoming along the inverted trough this afternoon at inland locations. Subsidence is expected to strengthen this afternoon at coastal locations as the trough moves west of I-75 and the upstream trough moves across the central Bahamas, which should result in decreasing rain chances by late afternoon along the I-95 corridor. Convection this afternoon along and west of the U.S. Highway 301 corridor will again be capable of producing very heavy downpours as deep tropical moisture prevails across our region, with an isolated stronger storm or two along the I-75 and U.S. Highway 84 corridors possible, with wet microburst potential and frequent lightning strikes. Activity should exit our region by sunset as the inverted trough moves westward through the FL Big Bend and stretches southward into the far eastern Gulf of Mexico. Localized flooding will be possible this afternoon, mainly for urban areas and saturated locations such as Alachua and Columbia Counties. Highs will generally reach the mid to upper 80s today as plenty of cloud cover prevails and convection initiates towards noon at inland locations. Dewpoints in the mid to upper 70s will create heat index values around 100 before convection becomes widespread this afternoon. We expect a lull in convective activity throughout our region this evening in between the departing trough and the upstream trough that will be moving through the Bahamas. Low level flow will back to east-northeasterly after midnight, with strengthening convergence combining with increasing PWAT values along the I-95 corridor that should develop scattered showers and a few thunderstorms over the Atlantic coastal waters after midnight that will likely move onshore towards sunrise. Lows tonight will only fall to the mid 70s inland and the upper 70s at coastal locations. The upstream inverted trough will progress westward across the northwestern Bahamas on Friday and will approach our coastal waters by Friday evening. This feature will likely produce waves of showers and thunderstorms that will progress across our region, with widespread activity expected during the afternoon hours at most inland locations. Deep tropical moisture will remain in place across our area, with repetitive downpours again creating the potential for localized flooding, particularly at urban and inland locations during the afternoon hours. A slightly later start to convection may allow highs to reach 90 at inland locations, with onshore winds keeping coastal highs in the mid to upper 80s. Dewpoints in the mid to upper 70s will likely result in heat index values of 100-105 by early afternoon before convection becomes widespread during the afternoon hours. .SHORT TERM [Friday Night Through Sunday Night]... Low and mid level flow will shift to easterly on Friday evening as the inverted trough axis crosses our area and then southeasterly for the weekend as the trough moves slowly westward into the eastern Gulf of Mexico and the FL panhandle. This trough may continue to generate scattered convection across much of our area on Friday evening, with activity then shifting to coastal locations overnight and Saturday morning. Drier air in the wake of the trough axis may then advect over coastal locations on Saturday afternoon and evening, with deeper moisture prevailing along the I-75 corridor, where another round of convection and heavy downpours are expected during the afternoon hours. Meanwhile, stronger high pressure will briefly build over New England, driving a cold front into the southeastern states towards the end of the weekend. Deepening and convergent southeasterly flow will continue to generate scattered convection at coastal locations Saturday night and Sunday morning, with another round of widespread convection expected inland on Sunday afternoon. Highs will generally reach the mid to upper 80s at coastal locations and around 90 inland each afternoon, with lows in the 70s. .LONG TERM [Monday Through Wednesday]... Deep-layered ridging will sink southward and will be positioned over our region on Monday as a progressive trough digs east- southeastward across New England and the Mid-Atlantic states. This trough will drive a backdoor cold front into southeast GA by late Monday. with this boundary then stalling over northeast FL on Tuesday as a strong surface ridge builds over New England and begins to wedge down the southeastern seaboard. Low level flow will back to easterly on Monday and then northeasterly by Tuesday and Wednesday, with increasing speeds possible by midweek as the surface ridge continues to wedge down the southeastern seaboard. This weather pattern will likely produce scattered to numerous showers and thunderstorms each day as the frontal boundary adds extra lift to the tropically moist air mass that will remain entrenched across our area. Highs around 90 on Monday will then fall back to the mid 80s towards midweek as northeasterly flow strengthens. Lows will remain in the 70s. .MARINE... ESE Winds near 10 kts with combined seas generally 3 ft or less today with showers and isolated tstorms, decreasing in coverage near the Atlantic coast in the evening. Rip Currents: Moderate risk today for all local beaches. High risk likely by Sun & into Mon due to long period easterly swells. && .PRELIMINARY POINT TEMPS/POPS... AMG 73 89 74 89 73 / 30 80 30 70 20 SSI 77 86 78 87 77 / 50 70 50 70 40 JAX 75 89 75 89 75 / 30 70 40 60 40 SGJ 77 87 77 88 77 / 30 60 40 60 40 GNV 74 90 74 90 74 / 20 80 30 60 20 OCF 74 91 74 90 74 / 40 80 40 70 20 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. &&
The national radar mosaic for the moment the first event began.
1 heavy rain. Local standard time, as filed.
An observer measured 3.03 inches of rain in less than one hour. Low water crossings in the area were flooded.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Georgia in 2020Every state in 2020This day in weather historyWarnings in Georgia, 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: 921549.