A saturated tropical airmass (PWAT over 2 inches) combined with diurnal instability and fueled locally heavy rainfall in showers and storms that formed near a meandering trough axis across north Florida and sea breezes. Weak storm motion enabled locally heavy rainfall to form and train over areas.
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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 saturated tropical airmass (PWAT over 2 inches) combined with diurnal instability and fueled locally heavy rainfall in showers and storms that formed near a meandering trough axis across north Florida and sea breezes. Weak storm motion enabled locally heavy rainfall to form and train over areas.
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, 2:36 PM EST, 1 hour 8 minutes earlier.
Area Forecast Discussion National Weather Service Jacksonville FL 336 PM EDT Sat Sep 18 2021 .NEAR TERM [Through Tonight]... A mid/upper low was moving slowly toward the Texas/Louisiana state border, allowing ridging to build westward from the Bahamas across the FL peninsula and towards the southeastern Gulf of Mexico. This set-up will continue steer abundant tropical moisture and impulses into the area. Scattered convection has developed along the sea breezes and will become numerous as the boundaries collide along the I-75 corridor by the late afternoon and evening hours. With slow storm motion and PWATs over 2 inches, heavy rainfall and localized flooding will be possible this afternoon into evening for inland areas. Activity will diminish before midnight near the Suwannee River, with an uptick in coastal convection expected during the predawn and early morning hours as onshore flow begins to deepen and shortwave energy moves overhead. Overnight lows will be in the 70s. .SHORT TERM [Sunday Through Monday]... A mid/upper low lingering over the lower Mississippi River Valley will weaken, elongate and lift to the northeast by Monday. Deep tropical moisture (PWATs > 2 inches) will continue to reside across the area resulting in numerous to widespread showers/storms mainly during the afternoon/evening hours into early next week. Sunday into Monday, high pressure over New England will wedge down the southeastern seaboard developing a coastal trough on Monday. This could result in short convective bands forming and dropping heavy rain along coastal areas. Areas of heavy rainfall and localized flooding may develop as cell motion will be on the slow side. Best chance will be in inland northeast Florida on Sunday and along the east coast on Monday. Temperatures will be around normal with highs in the mid to upper 80s and lows in the 70s. .LONG TERM [Tuesday Through Friday]... Numerous to widespread showers/storms continue into Wednesday as deep tropical moisture lingers over the area. A weakening ridge of high pressure along the east coast will shift offshore as an upper trough digs into the eastern U.S. PWATS around 2 inches along with light steering winds will result in slow moving showers/storms with locally heavy rainfall and localized flooding as a continued threat. A cold front will push through the area Wednesday night into Thursday. A cooler, drier airmass filters in from the northwest for the end of the week lowering rain chances and overnight lows into the low to mid 60s for inland areas. && .AVIATION... [Through 18Z Sunday] Showers and thunderstorms will continue to develop near the inland terminals throughout the afternoon hours, with coverage shifting west of the Duval County terminals by 00Z and potentially lingering at GNV through around 02Z. We included TEMPO groups at JAX, VQQ, and GNV terminals this afternoon for briefly gusty winds and periods of IFR visibilities during heavier downpours. Outside of convection, northeast to easterly winds will remain sustained at 5-10 knots towards 17Z. IFR to MVFR conditions should develop at the regional terminals after 17Z, with fog possible inland and lower stratus ceilings developing at VQQ and GNV after 07Z Sunday. Showers and thunderstorms should approach the coastal terminals after 11Z Sunday, and we included PROB30 groups for MVFR to IFR conditions and briefly gusty winds on Sunday morning at SSI, SGJ, and CRG. && .MARINE... Stronger high pressure builds southeastward from the Great Lakes towards New England. This feature will wedge down the southeastern seaboard on Sunday, resulting in coastal trough development over our near shore waters by late Sunday and Monday. Abundant tropical moisture will result in widely scattered thunderstorms over our waters through tonight, followed by increasing activity from Sunday night through Tuesday due to the presence of the coastal trough. A cold front will then enter the southeastern states towards midweek, passing through our waters on Thursday. Seas of 2-4 feet will otherwise prevail throughout our coastal waters through midweek. Rip Currents: Moderate risk of rip currents anticipated through the weekend for all area beaches. && .HYDROLOGY... Minor flooding continues along lower portions of the Santa Fe River near the Three Rivers Estates gauge. Runoff from widespread convection will likely result in river rises further upstream along the Santa Fe as well as the St. Marys and Satilla River basins, although these river levels are currently expected to peak in action stages rather than reaching flood stage through the middle portion of next week. This still is highly dependent on where the heaviest rain falls. Locally heavy rainfall and localized flooding will be possible over the next few days with WPC showing marginal risk of excessive rainfall. Estimated rainfall amounts into Monday are around 1-2 inches, with locally higher totals possible. && .PRELIMINARY POINT TEMPS/POPS... AMG 72 86 71 85 71 / 20 50 30 80 30 SSI 77 85 76 85 75 / 40 60 60 80 60 JAX 74 87 74 86 74 / 40 70 40 80 40 SGJ 76 85 74 85 74 / 40 60 40 80 50 GNV 73 87 71 87 71 / 60 80 40 80 30 OCF 73 88 73 88 73 / 60 80 30 80 30 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. &&
The Jacksonville radar (KJAX), 116 km away, was scanning. The volume nearest the first event began at 20:45 UTC.
2 heavy rain, 1 tornado, 1 flood. Local standard time, as filed.
An AWS mesonet site measured 3.58 inches of rainfall in the past 6 hours. About 2.07 inches fell in the past hour.
Multiple social media images showed a waterspout that formed over Orange Lake, just north of Citra. The waterspout persisted for about 10 minutes. All parameters were estimated, including the path width and track length and EF scale. There were no reported damage or injuries.
A Weather Underground station measured 3.40 inches that began around 8:45 pm. Nearby stations measured around 3.5 inches.
Flooded streets were reported across the westside of Gainesville including the following areas: SW 45th Street, SW 194th Street and around the 16000 block of NW 143rd Street.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Florida in 2021Every state in 2021This day in weather historyThe tornado archive for Florida, 2021Warnings in Florida, September 2021
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: 979670, 979678, 979671, 979667.