Deep west to southwest flow prevailed throughout the column and widespread|showers and storms quickly moved inland from the Gulf coast in the late|morning to early afternoon hours toward the east coast. A weak east coast sea breeze was near the Atlantic coast, and convergence of the sea breezes and outflow boundaries resulted in storm to storm storms with enhancement from a passing shortwave…
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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.
Deep west to southwest flow prevailed throughout the column and widespread|showers and storms quickly moved inland from the Gulf coast in the late|morning to early afternoon hours toward the east coast. A weak east coast sea breeze was near the Atlantic coast, and convergence of the sea breezes and outflow boundaries resulted in storm to storm storms with enhancement from a passing shortwave aloft.
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 Jul 19, 9:37 AM EST, 2 hours 8 minutes earlier.
Area Forecast Discussion National Weather Service Jacksonville FL 1037 AM EDT Mon Jul 19 2021 .UPDATE... The 12Z sounding this morning showed a very moist profile with precipitable water values greater than 2.1 inches. Deep west to southwest flow prevailed throughout the column, and widespread showers/storms will quickly move from the Gulf coast in the late morning to early afternoon hours towards the east coast. A weak east coast sea breeze will be pinned to I-95 and to the coast, with some stronger storms possible along the coastal areas today. A shortwave will move across southern Georgia late this afternoon, and shower/thunderstorm activity will be enhanced across this area during that time. Showers/storms may linger into the evening due to the shortwave. The quick westerly flow may also bring some showers and embedded storms into the Suwannee Valley overnight from the Gulf of Mexico. Highs today are forecast to be in the upper 80s to around 90 degrees. && .PREV DISCUSSION [751 AM EDT]... .NEAR TERM [Through Tonight]... Troughing aloft over the eastern U.S. will bifurcate as the aforementioned potent shortwave entering New England progresses eastward, leaving a cutoff trough over the Tennessee Valley and the Ozarks by tonight. Flow aloft locally will back to a more westerly direction today, and support for the frontal zone well to the north of our region will weaken. The westerly flow will continue to advect deep tropical moisture into our region, and the departing weak shortwave to our north should allow for at least filtered sunshine this morning across most of our region, allowing temperatures to quickly climb through the 80s. Showers and thunderstorms should be initiated towards noon by the inland moving Gulf coast sea breeze over western portions of the Suwannee Valley, and this activity should increase in coverage and intensity as it progresses eastward this afternoon, reaching the Atlantic coast by late afternoon. Our local pressure gradient should remain weak enough for the Atlantic sea breeze to develop early this afternoon, with this boundary likely remaining pinned to the east of I-95 through the afternoon hours. Model soundings indicate ML CAPE values rising to 1,500 - 2,000 j/kg by early afternoon as temperatures approach 90 degrees all the way to coastal locations. Mesoscale boundary collisions and the tropical air mass in place should result in widespread thunderstorm coverage as activity approaches the U.S. Highway 301 corridor by mid-afternoon, and a few storms may pulse and become strong as convection intersects the pinned Atlantic sea breeze boundary during the mid to late afternoon hours for locations along and east of I-95. Pulsing storms will be capable of producing downburst winds of 40-55 mph, frequent lightning strikes and briefly torrential downpours late this afternoon. Thunderstorms should mostly move offshore by the early afternoon hours, but weak shortwave energy migrating across the southeastern states may touch off a round of at least widely scattered convection early this evening, mainly for inland portions of southeast GA and northern portions of the Suwannee Valley. Expect debris cloudiness to linger overnight due to evening convective development over southeast GA and the presence of the cutoff trough to our northwest. Lows tonight will generally fall to the low and mid 70s area-wide. .SHORT TERM [Tuesday Through Wednesday]... Southwesterly flow will continue through into midweek, with moisture levels gradually decreasing over the region as high pressure ridging to the south expands it's influence northward due to the weakening of the troughing over the eastern US. Mostly diurnal showers and thunderstorms are expected to be more prevalent on Tuesday as PWAT values drop from about 2 inches down to 1.75 inches on Wednesday over much of the area, with a potential for excessive rainfall near coastal southeast Georgia on Tuesday during the afternoon and evening hours where PWAT values are currently expected to be in excess of 2.25 inches. Daytime high temperatures will be in the upper 80s and lower 90s on Tuesday and Wednesday with cooler temps occurring over areas with dense cloud cover and heavier rains. Overnight low temperatures will be in the lower 70s during this period. .LONG TERM [Thursday Through Monday]... The more typical summertime pattern of diurnal showers and storms will return for the end of the week, with a potential for increased convection over the weekend as the effects of a possible broadening trough off to the north influences the placement of high pressure ridging over northeastern Florida and southeastern Georgia, resulting in an overall decrease in stability. Temperatures during this period are expected to be slightly above the climatological average for the end of the week and for the weekend. .AVIATION... [Through 12Z Tuesday] Showers and storms will form along the Gulf coast this morning and spread across the rest of the area by the early to mid afternoon hours. Restrictions are expected at the TAF sites this afternoon, with showers/storms ending by the early evening. Showers could get near KGNV overnight as they move in from the Gulf again. Light winds will become southwest 5-10 knots. A weak east coast sea breeze will push through the coastal TAF sites in the mid afternoon, with winds then shifting back to the southwest by the evening. .MARINE... The axis of Atlantic high pressure will remain positioned to the south of our local waters this week as a frontal boundary stalls over the southeastern states and weakens towards midweek, leaving a weak trough positioned near the Georgia waters. A few strong thunderstorms containing strong wind gusts and frequent lightning strikes will move eastward over the near shore waters during the mid to late afternoon hours today and again on Tuesday. Southwesterly winds will prevail, but will be weak enough for the sea breeze to develop over the near shore waters by the mid to late afternoon hours through midweek. Coverage of showers and thunderstorms will likely decrease on Wednesday and Thursday, followed by increasing coverage towards Friday afternoon. Seas of 2-4 feet will prevail throughout the near shore and offshore waters during the next several days. Rip Currents: Prevailing offshore winds and low wave heights will result in a low risk at area beaches throughout the work week. .HYDROLOGY... Rivers continue to recede across our region, with mostly minor flooding ongoing along the lower Santa Fe and portions of the St. Marys Rivers. River levels have mostly fallen just below flood stage along the lower Satilla River. Minor flooding will continue this week along most of the lower Santa Fe River. && .PRELIMINARY POINT TEMPS/POPS... AMG 88 72 88 71 91 / 80 60 80 20 60 SSI 88 76 89 77 91 / 80 40 70 20 40 JAX 89 73 91 74 93 / 80 30 70 10 50 SGJ 88 74 90 74 90 / 80 40 60 20 40 GNV 88 72 89 72 91 / 70 20 70 10 60 OCF 89 73 90 73 91 / 70 20 60 10 60 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. &&
The Moody AFB radar (KVAX), 75 km away, was scanning. The volume nearest the first event began at 16:44 UTC.
4 thunderstorm wind, 1 lightning, 1 heavy rain. Local standard time, as filed.
Multiple trees were blown along 12th Ave. Hail of unknown size was also reported. Cost of damage was unknown, but it was estimated for inclusion of the event in Storm Data.
Power lines were down and damaged along Fouraker Road, just south of Normandy Blvd. There was power disruption to over 300 customers. The time of damage was based on radar.
Trees and debris were blown into power lines that caused power outages to over 65 residences near the intersection of Old Middleburg Road and Lenox Ave. The time of damage was based on radar.
Trees and tree debris were blown down onto power lines in the Lakeshore Area along Edgewood Avenue near the intersection with Marion Street. The time of damage was based on radar.
Lighting struck a 2 story storage shed along Bay Drive and caused a fire. The cost of damage was estimated.
The NWS CoCoRaHS station at the Jacksonville Airport measured a storm total rainfall of 3.01 inches.
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, July 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: 965503, 965508, 965506, 965509, 965504, 965510.