Early morning strong to isolated severe storms formed ahead of a frontal boundary over a moist and moderately unstable airmass with passing level short wave trough energy aloft. An outflow boundary ahead of the small MCS-like cluster of storms pressed southward during the late morning and afternoon hours which further convective enhancement, triggering pulse strong to severe storms.
Every event with a place to put it. Tap one for its entry below.
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.
Early morning strong to isolated severe storms formed ahead of a frontal boundary over a moist and moderately unstable airmass with passing level short wave trough energy aloft. An outflow boundary ahead of the small MCS-like cluster of storms pressed southward during the late morning and afternoon hours which further convective enhancement, triggering pulse strong to severe 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 Oct 7, 7:12 PM EST, 3 hours 48 minutes earlier.
Area Forecast Discussion National Weather Service Jacksonville FL 812 PM EDT Thu Oct 7 2021 .UPDATE... Low level moisture persists across the region which could lead to another round of significant fog Tonight. The best chance for denser fog will be across NE FL and coastal SE GA, as showers will move into western counties during the night. Isolated to scattered showers will be across the area by around sunrise, with chances increasing through the day on Friday. A round of thunderstorms is expected Friday as low pressure moves across forecast area, with the potential for a few strong to severe storms. As the low center itself crosses during the day Friday with a warm front extending east of low, storms will need to be monitored for isolated tornadoes, in addition to wind gust and heavy rainfall potential. && .AVIATION... [Through 00Z Saturday] Low level moisture will result in restrictions in stratus and fog overnight. Showers and thunderstorm coverage will increase through the day on Friday. && .PREV DISCUSSION [501 PM EDT]... .NEAR TERM [Through Friday]... A few strong thunderstorms will be possible through early this evening, mainly between the Interstate 75 corridor and U.S. Highway 301, as mesoscale boundaries collide and convection potentially taps into westerly bulk shear around 30 knots. These values and surface-based CAPE values around 1,500 j/kg could result in a few downbursts of up to around 40 mph, but locally heavy rainfall and frequent lightning strikes look to be the bigger threats through early this evening. Otherwise, a shortwave trough will sharpen overnight over the lower Mississippi Valley and will move eastward across our region on Friday afternoon and evening. In advance of this feature, strong surface ridging building into the Mid-Atlantic states will begin to push a backdoor cold front southward down the southeastern seaboard, and this boundary will likely develop numerous showers and a few embedded thunderstorms near the Altamaha/Ocmulgee/Alapaha Rivers in southeast GA after midnight, with this activity slowly shifting southward as it increases in coverage on Friday morning. Low stratus and at least patches of fog will be possible overnight through around sunrise on Friday across north central and northeast FL, mainly inland, although increasing high altitude cloudiness should limit the potential for dense fog formation. Lows tonight will only fall to the low and mid 70s. Widespread showers and a few embedded thunderstorms will develop along and ahead of the southward moving cold front across southeast GA on Friday morning. Filtered sunshine is expected across northeast and north central FL by the mid to late morning hours after low stratus and fog lifts into a healthy cumulus field, boosting highs to the mid and upper 80s before the aforementioned shortwave trough and frontal boundary arrive during the afternoon hours. Latest HREF guidance indicates the potential for widespread heavy downpours all along the I-95 corridor by the late afternoon hours, and a few strong thunderstorms may also be possible along an Atlantic sea breeze boundary that will likely also be oriented along the I-95 corridor. Widespread rainfall amounts of 1-1.5 inches are expected through Friday evening along the I-95 corridor, with locally higher amounts possible where storms train or move slowly over the same locations. Activity will likely be more scattered for locations west of the U.S.-301 corridor as some drier air advects into these locations by late afternoon. Highs will likely be held to the 80-85 range across southeast GA, where convection will be ongoing during the morning hours and will be slow to shift southward during the afternoon. .SHORT TERM [Friday Night through Sunday Night]... Troughing will continue to sharpen along the southeastern seaboard on Friday night and Saturday, with a potent shortwave expected to dive southeastward across our region on Saturday afternoon. This feature will develop a cutoff trough off the southeast FL coast and over the northwestern Bahamas by Saturday night and Sunday. Meanwhile, the frontal boundary will continue to shift south of our area after midnight on Friday night, bringing convection to an end from west to east overnight. Locally heavy downpours and a few strong thunderstorms may continue through around midnight along the northeast FL coast, followed by a cooler and drier air mass advecting into our region by the predawn hours on Saturday as low level winds shift to north-northwesterly. Lows will fall to the mid 60s for inland southeast GA and the northern Suwannee Valley, ranging to the lower 70s along the northeast FL coast. The aforementioned potent shortwave trough may redevelop widely scattered showers for locations east of Interstate 75 and U.S. Highway 441 on Saturday, mainly during the afternoon hours. Low pressure strengthening near North Carolina's Outer Banks will likely result in breezy north-northeasterly winds developing at coastal locations during the afternoon hours. Morning sunshine and a drier low level air mass should allow highs to climb to the low and mid 80s, with a few upper 80s possible for locations south of Gainesville. The shortwave trough will then dive south- southeastward towards Cape Canaveral on Saturday evening, with only isolated to widely scattered showers possible for the balance of the weekend along the northeast FL coast, mainly south of St. Augustine, as PWAT values fall below 1.5 inches. Decoupling winds at inland locations will allow lows to fall to the low to mid 60s, while a northeasterly breeze keeps coastal lows in the upper 60s to around 70 on Saturday and Sunday nights. Highs on Sunday will again reach the low to mid 80s, with a few inland locations in north central FL climbing to the upper 80s. .LONG TERM [Monday Through Wednesday Night]... Cutoff troughing will continue to meander off the southeast FL coast and the northwestern Bahamas on Monday before slowly filling as ridging aloft builds over the Gulf of Mexico and expands northeastward into the southeastern states. Deep northeasterly flow will keep enough Atlantic moisture in place to develop diurnal rounds of scattered showers along the I-95 corridor, with some activity possible at area beaches during the morning hours, with activity then shifting inland towards the U.S.-301 corridor each day through midweek. Temperatures will slowly climb to the mid and upper 80s inland early next week as heights aloft begin to rise, while onshore winds keep coastal highs in the lower 80s. Temperatures could approach 90 by midweek at some inland locations. Lows will also slowly climb, with low to mid 60s inland on Monday night rising to the upper 60s by Wednesday night. Coastal lows will generally remain in the 70-75 degree range as an onshore breeze prevails. .MARINE... Weak low pressure located off the South Carolina coast will meander northward, reaching the North Carolina Outer Banks by late Saturday as strong high pressure remains in place over New England and the Canadian Maritime region. This high pressure center will push a frontal boundary southward across the Georgia waters early on Friday morning, producing widespread showers and thunderstorms across our coastal waters from Friday morning through early Saturday. The front will continue moving slowly southward through the Florida peninsula this weekend, resulting in north and northeasterly winds this weekend, accompanied by widely scattered showers, especially over the northeast Florida waters. High pressure will then shift over the southeastern states on Tuesday and Wednesday, keeping light onshore winds in place locally. Rip Currents: A persistent easterly ocean swell and developing onshore winds by Saturday afternoon will keep a moderate risk in place at all area beaches through the weekend .FIRE WEATHER... Light surface and transport winds will result in low daytime smoke dispersion values area-wide on Friday. Patchy fog and low clouds are expected to develop across northeast and north central Florida during the predawn and early morning hours on Friday, mainly at inland locations. Surface and transport winds will shift to north or north-northwesterly on Saturday morning, with surface winds then shifting to northeasterly and becoming breezy at coastal locations during the afternoon. Breezy northeasterly surface and transport winds will continue at coastal locations on Sunday. .HYDROLOGY... Minor flooding along lower portions of the Santa Fe River near the Three Rivers Estates gauge will likely fall below flood stage by late Friday. High astronomical tides should bring water levels up to action stage along the Atlantic coast during times of high tide through early next week. Significant coastal flooding is not anticipated, but rainfall runoff may be impeded at coastal locations during times of high tide on Friday and Friday night. && .PRELIMINARY POINT TEMPS/POPS... AMG 72 82 64 83 63 / 40 70 40 20 10 SSI 75 83 70 82 68 / 20 80 60 40 30 JAX 73 86 68 84 66 / 20 80 60 40 20 SGJ 74 85 71 83 70 / 10 70 60 40 30 GNV 72 86 67 85 65 / 20 70 60 30 20 OCF 73 87 69 86 66 / 20 60 60 30 10 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. &&
The Jacksonville radar (KJAX), 1 km away, was scanning. The volume nearest the first event began at 03:57 UTC.
3 heavy rain, 1 thunderstorm wind. Local standard time, as filed.
The Jacksonville (JAX) ASOS measured a storm total rainfall of 2.21 inches as of 1:32 pm.
The Naval Station Mayport AWOS measured a storm total rainfall of 2.63 inches. The time duration was estimated.
An observer measured 1.25 inches of rainfall in a short duration which caused minor street flooding. The time was estimated.
A tree was blown down across State Road 100 and County Road 205. The tree was across the west bound lane.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Florida in 2021Every state in 2021This day in weather historyWarnings in Florida, October 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: 978796, 978797, 978795, 978798.