A deep upper level trough was across the area with cooler temperatures aloft. Southwest steering flow brought a more dominant west coast sea breeze which triggered strong to pulse severe storms as they tracked toward the east in the afternoon over an unstable airmass.
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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 deep upper level trough was across the area with cooler temperatures aloft. Southwest steering flow brought a more dominant west coast sea breeze which triggered strong to pulse severe storms as they tracked toward the east in the afternoon over an unstable airmass.
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 23, 9:53 AM EST, 3 hours 7 minutes earlier.
Area Forecast Discussion National Weather Service Jacksonville FL 1053 AM EDT Mon Aug 23 2021 ...STRONG THUNDERSTORMS POSSIBLE ALONG THE I-95 AND I-10 CORRIDORS THIS AFTERNOON... .UPDATE... Late morning surface analysis depicts Atlantic high pressure (1022 millibars) centered just east of Bermuda and extending its axis southwestward across the FL peninsula. Meanwhile, troughing extends southward from Henri's remnants across the Deep South. Aloft...troughing situated along the eastern seaboard was digging southward towards our region, with ridges centered over eastern Texas and east of Bermuda. Latest RAP/LAPS analyses indicate that deep tropical moisture remains in place locally, with PWAT values around or above 2 inches region-wide, with higher surface-based CAPE values above 2,000 j/kg in place for locations along and south of Interstate 10, while lower values were in place for locations north of Waycross. A few sprinkles may be falling for locations south of I-10 beneath a mid level cloud deck that was progressing quickly southeastward while thinning. Patches of mainly mid and high altitude cloud cover were otherwise scattered across the rest of our area, with an outflow boundary emanating from an earlier Mesoscale Convective System (MCS) that impacted the FL panhandle during the predawn hours now initiating a line of convection along the water logged FL Nature Coast that was progressing east-southeastward towards southern portions of the Suwannee Valley, with additional showers now developing eastward along the FL/GA border. Breaks in the cloud cover were allowing temperatures to rise to the low and mid 80s at 15Z, with dewpoints mostly in the muggy 75-80 range. Deep-layered troughing will continue to dig into our region from north to south this afternoon, with this troughing possibly cutting off overnight near the Gulf Stream waters. This feature will result in slight cooling of the mid-levels locally this afternoon, with convection expected to increase in coverage towards noon over the Suwannee Valley and for locations near the FL/GA border along an existing gradient in CAPE values mentioned previously. Activity should progress east-southeastward while increasing in coverage as convection crosses the U.S. Highway 301 corridor. Brisk low level southwesterly flow will pin the Atlantic sea breeze along the Atlantic coast through the afternoon hours. Convection may pulse and become strong at area beaches as activity encounters this pinned sea breeze boundary. Stronger storms today will be capable of producing downburst wind gusts up to 55 mph, frequent lightning strikes, and locally heavy downpours. Scattered convection will be possible elsewhere late this afternoon and early this evening as outflow boundaries potentially trigger new convection beneath gradually cooling temperatures and steepening lapse rates aloft. Highs will generally reach the lower 90s before convection increases in coverage during the early to mid afternoon hours, with maximum heat index values climbing to around 105 degrees. At least scattered convection may linger through around midnight as the deep-layered trough swings southeastward through our region, followed by convection blossoming offshore overnight as this trough becomes cutoff. Debris cloud cover may be slow to thin through the predawn hours, and lows will generally fall to the mid 70s inland and the upper 70s at coastal locations. && .MARINE... A trough digging southeastward into our region this afternoon will enhance thunderstorm coverage through tonight. Outside of thunderstorm activity, south-southeasterly winds will increase to around 15 knots by late afternoon and will then shift to southerly and may surge to Caution levels of 15 to 20 knots this evening before diminishing overnight. The axis of Atlantic high pressure will then lift northward from the Florida peninsula to a position east of the North Carolina Outer Banks by midweek, resulting in prevailing southerly winds on Tuesday, followed by onshore winds during the middle and late portions of this week. Seas of 3-5 feet will prevail both near shore and offshore through Wednesday night. A weak trough will push westward across our local waters by late Wednesday, resulting in increasing coverage of showers and thunderstorms late this week. Seas will build to Caution levels of 4 to 6 feet offshore by Thursday. Rip Currents: A persistent east-southeasterly ocean swell will keep a low-end moderate risk at the northeast FL beaches through Tuesday. Onshore winds and building seas may increase the threat late this week at all area beaches. && .FIRE WEATHER... Brisk southwesterly transport winds will prevail today for locations south of Waycross, resulting in good smoke dispersion values for locations along and south of Interstate 10. Surface and transport winds will then shift to southerly on Tuesday with decreasing speeds, resulting in marginally low dispersion values at inland locations. && .HYDROLOGY... Levels are about to fall below moderate flood status at the Three Rivers Estates gauge along the lower Santa Fe River, with moderate flooding also subsiding along the Ichetucknee River. Minor flooding will continue along upper portions of the Suwannee through at least midweek, with minor flooding continuing this week along lower portions of the Santa Fe and for the lower Suwannee River south of the confluence with the Santa Fe. && .PREV DISCUSSION [757 AM EDT]... .NEAR TERM [Through Tonight]... A cutoff mid to upper level low over the Mid Atlantic states will move northeastward into the western Atlantic waters while ridging aloft will be centered to our west over the Arklatex region with north to NW mid to high level flow over our area. Southwest low level flow along and ahead of a surface trough hanging out over central GA into the Carolinas, moist PWATs near 2.0 inches, and shortwave energy traveling around the base of the southern portion of the exiting trough will help initiate scattered to numerous showers and thunderstorms over the area with the best focus along I-10 into coastal SE GA where the surface trough will be positioned late in the day. Storms will move eastward along the I-10 corridor of NE FL and then over the coastal waters by around sunset with residual showers remaining over the coast and into portions of NE FL through midnight as a weak low develops over the coastal waters along the surface trough. Slow storm motions from the west will veer northwest through the afternoon and then north through the evening and bring a risk for locally heavy rainfall that could lead to minor flooding. Gusty wind potential up to 50 mph will also be possible in the strongest storms and also small hail as lapse rates increase to around 6.0 to 6.5 C/Km during peak diurnal heating, but any severe storm potential should be limited as mid level temperatures stay a little warmer than climatology with values near -6.0 degrees Celsius. High temperatures will be in the low 90s over NE FL along I-95 and the St Johns river basin with near 90 readings for inland NE FL, SE GA areas and the NE FL beaches with upper 80s at the SE GA coast. Tonight, mostly cloudy skies and showers will linger along the SE GA coast and over NE FL areas after storms push into the coastal waters after sunset. Gradual clearing is expected after midnight over inland areas with some low clouds and fog possible west of Waycross during the predawn hours. Lows will be in the mid 70s inland and the upper 70s at the coast. .SHORT TERM [Tuesday Through Wednesday]... An upper trough will lift north up the western Atlantic as the Bermuda high builds westward over the region shifting the flow from southerly on Tuesday to east-southeasterly on Wednesday. Lingering upper impulses and ample moisture will result in numerous showers and storms across the area with the highest precipitation chances between the I-95 and I-75 corridors where the sea breezes are expected to converge. On Wednesday, drier air advects into the region from the southeast ahead of an easterly wave making its way up the Florida east coast. This will result in less convective coverage on Wednesday mainly over northeast Florida. With easterly flow and drier air over northeast Florida, best chance for storms on Wednesday will be along the I-75 corridor and inland southeast Georgia as the Atlantic sea breeze pushes inland. Temperatures will be around normal with highs in the upper 80s to low 90s and lows in the 70s. .LONG TERM [Thursday Through Sunday]... Low to mid level ridging remains over the region continuing easterly flow through the weekend. An easterly wave moves from central Florida into the Panhandle Thursday into Friday. This will bring additional moisture and lift to the area which could potentially enhance precipitation. Otherwise, typical summertime pattern of scattered to numerous showers and storms developing along the sea breezes prevails through the weekend. Temperatures will be near average August levels. .AVIATION... [Through 12Z Tuesday] Periods of MVFR ceilings between 2000-3000 feet and brief light showers will be possible at the regional terminals through around 15Z. VFR conditions will otherwise prevail, and we will issue amendments to cover the brief nature of the MVFR ceilings this morning. Showers and thunderstorms will develop along the Interstate 10 corridor and coastal southeast GA after 16Z, with activity moving east or east southeastward towards the regional terminals and the I-95 corridor early this afternoon. We included TEMPO groups at all of our TAF sites for IFR to MVFR visibilities within heavier downpours, along with wind gusts up to 30 knots and MVFR ceilings. Activity may linger or even redevelop into the evening hours for locations south of Interstate 10, and we kept VCTS for VQQ, GNV and SGJ after 00Z. Southwesterly surface winds will be sustained at 5-10 knots through around 17Z, with the Atlantic sea breeze boundary expected to cross the coastal terminals after 17Z, resulting in surface winds shifting to south-southeasterly and increasing to 10-15 knots. Outside of thunderstorm activity, southwesterly surface winds sustained around 10 knots will prevail at the inland terminals through around 23Z. Surface winds will shift to southerly and will remain sustained at 5-10 knots overnight at the coastal terminals, with southwesterly winds sustained around 5 knots or less at the inland terminals. && .PRELIMINARY POINT TEMPS/POPS... AMG 91 73 92 73 89 / 50 40 60 60 60 SSI 90 77 89 76 88 / 70 60 50 50 40 JAX 92 74 90 73 89 / 60 60 50 50 40 SGJ 93 76 88 76 88 / 50 60 50 50 30 GNV 92 75 89 73 89 / 50 30 60 40 40 OCF 91 75 89 73 90 / 30 30 60 20 40 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. &&
Special Weather Statement
National Weather Service Jacksonville FL
1257 PM EDT Mon Aug 23 2021
FLZ023-122-222-GAZ364-231745-
Southern Columbia FL-Baker FL-Northern Columbia FL-
Western Charlton GA-
1257 PM EDT Mon Aug 23 2021
...A strong thunderstorm will impact portions of Baker, northeastern
Columbia and south central Charlton Counties through 145 PM EDT...
At 1256 PM EDT, Doppler radar was tracking a strong thunderstorm 8
miles west of Taylor, or 19 miles northeast of Lake City, moving east
at 30 mph.
HAZARD...Winds in excess of 40 mph and minor flooding due to heavy
rainfall.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor flooding due to heavy rainfall is
possible.
Locations impacted include...
Taylor, Macclenny, Glen St. Mary, Sanderson, Olustee and Watertown.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.
Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
&&
LAT...LON 3053 8258 3058 8233 3057 8222 3060 8220
3063 8205 3017 8205 3019 8262
TIME...MOT...LOC 1656Z 266DEG 25KT 3042 8244
MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH
NELSONSpecial Weather Statement
National Weather Service Jacksonville FL
125 PM EDT Mon Aug 23 2021
FLZ023-024-124-125-225-325-425-GAZ165-364-231815-
Baker FL-Western Duval FL-South Central Duval FL-Inland Nassau FL-
Trout River FL-Coastal Nassau FL-Coastal Duval FL-Inland Camden GA-
Western Charlton GA-
125 PM EDT Mon Aug 23 2021
...A strong thunderstorm will impact portions of Nassau, northeastern
Baker, central Duval, southern Camden and southeastern Charlton
Counties through 215 PM EDT...
At 125 PM EDT, Doppler radar was tracking a strong thunderstorm 8
miles east of Taylor, or 20 miles southwest of Callahan, moving east
at 25 mph.
HAZARD...Wind gusts of 45 to 55 mph and minor flooding due to heavy
rainfall.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor flooding due to heavy rainfall is
possible.
Locations impacted include...
Jacksonville, Hilliard, Callahan, Jacksonville International Arpt,
Macclenny, Cisco Gardens, St. George, Bryceville, Nassau
Village-Ratliff and Ratliff.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.
Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
&&
LAT...LON 3029 8166 3028 8224 3057 8226 3057 8222
3063 8219 3077 8169 3074 8169 3074 8167
3075 8167 3075 8165 3073 8165 3073 8164
TIME...MOT...LOC 1725Z 266DEG 24KT 3043 8215
MAX HAIL SIZE...0.00 IN
MAX WIND GUST...55 MPH
NELSONThe Jacksonville radar (KJAX), 24 km away, was scanning. The volume nearest the first event began at 18:01 UTC.
3 thunderstorm wind. Local standard time, as filed.
A tree was blown down at Old Dixie Highway and Bethel Church Road. The time of damage was based on radar.
A power line as blown down at 13941 New Kings Road.
A tree was blown down along I-95 southbound at mile marker 377. The cost of damage was unknown but it was estimated for the event to be included in Storm Data.
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, August 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: 973198, 973200, 973199.