Talking the Tropics With Mike: Last day of the Atlantic hurricane season!

Jacksonville, Fl. — THE TROPICS:

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Tropics threats/impacts for Jacksonville/NE Florida/SE Georgia: None.

The Atlantic Basin Overview:

The Atlantic hurricane season is June 1st through Nov. 30th.

The average date of the third named storm of the season is August 3rd.

Early last Wed. the NHC outlined a yellow area (“low chance”) over the NE Gulf extending across Fl. & the SE U.S. coast which has since been shifted west & was colored in red (“high chance”) by early Sunday & upgraded to tropical depression #2 late Sunday morning. Then hurricane hunter aircraft determined t.d. #2 had strengthened into tropical storm Bertha Mon. evening. A very disorganized Bertha made landfall about 3pm EDT 40 miles east of New Orleans. All of the strong t’storms were far to the southwest of the swirling center. Estimated intensity was 45 mph but no sustained tropical storm force winds were being measured over land at the time of landfall. Bertha made a second landfall early Thu. afternoon near the Texas/Louisiana state line - again largely devoid of much significant t’storm activity near its center nor of any sustained winds at tropical storm strength over land. Bertha was then downgraded to a depression Thu. evening where a quick burst of t’storms did produce some short term flooding... the NHC declared the stretched out system “dissipated” later Thu. evening.

Bertha’s development was a pretty classic “top/down” formation of a tropical cyclone as a surface low pressure finally emerged beneath a persistent upper low that was over the NE Gulf for several days. Thunderstorm clusters waxed & waned south & southwest of the “center” throughout Bertha’s lifetime due to moderate to strong & persistent mid & upper level wind shear out of the northeast. The favorable MJO phase + warm water temps + a decent amount of moisture (though is some dry air being absorbed from the NE over the continental U.S.) seemed to be enough to at least maintain a solid circulation center despite being largely devoid of convection most of the time.

Next on the Atlantic list: Cristobal, but there’s nothing cookin’ anytime soon.

‘Velocity potential anomalies’ below. “Rising” air (green lines) equates with an uptick in overall convection. With rising air, conditions are generally more favorable for tropical development. Where there are brown lines, the air is generally sinking & is often less conducive to tropical cyclones (though not impossible to have development).

The “Buresh Bottom Line”: Always be prepared!.....First Alert Hurricane Preparation Guide... City of Jacksonville Preparedness Guide... Georgia Hurricane Guide.

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Federal Alliance for Safe Homes (FLASH) * here *.

REMEMBER WHEN A TROPICAL STORM OR HURRICANE IS APPROACHING: Taping windows is *not* recommended & will not keep glass from breaking. Instead close curtains & blinds.

Realize the forecast cone (”cone of uncertainty”) is the average forecast error over a given time - out to 6 days - & *does not* indicate the width of the storm &/or where damage might occur.

The map below shows the *average* time for a tropical wave coming off Africa to travel west & northwest. Only about 1 in 5 tropical waves - on average - become a tropical cyclone of some sort (depression/storm/hurricane):

Water vapor loop (dark blue/yellow is dry mid & upper level air):

July Atlantic tropical cyclone origins:

Averages below based on climatology for the Atlantic Basin for July:

Wind shear (red - strong shear; green - low shear). Shear is typically strong to start the hurricane season:

Saharan dust spreads west each year from Africa driven by the prevailing winds (from east to west over the Atlantic). Dry air = yellow/orange/red/pink. Widespread dust is indicative of dry air that *can* interfere with the development of tropical cyclones. However, sometimes “wanna’ be” waves will just wait until they get to the other side of - or away from - the dust plume then try to develop if other conditions are favorable (we saw this with Beryl & Debby last year). It’s my personal opinion that there is way too much “hoopla” about the presence of Saharan dust & how it relates to tropical cyclones. In any case, the peak of Saharan dust typically is in June & July, & we are indeed seeing a large “blobs” of Saharan dust over the Central & Eastern Atlantic that’s thinning with westward extent but enough of it to make for hazy skies across the Caribbean & - at times - across parts of Florida.

2026 names..... “Cristobal” is the next name on the Atlantic list (names are picked at random by the World Meteorological Organization... repeat every 6 years). Historic storms are retired [Florence & Michael in ’18... Dorian in ’19 (the last time this year’s list was used) ... Laura, Eta & Iota in ‘20 ... Ida in ‘21 ... Fiona & Ian in ‘22... no names were retired in ‘23 for the first time since 2014... Beryl, Helene & Milton in 2024 & Melissa in 2025). The WMO decided - beginning in 2021 - that the Greek alphabet will be no longer used & instead there will be a supplemental list of names if the first list is exhausted (has only happened three times - 2005, 2020 & 2021). The naming of tropical cyclones began on a consistent basis in 1953. More on the history of naming tropical cyclones * here *.

Hurricane season climatology:

East Atlantic:

Mid & upper level wind shear (enemy of tropical cyclones) analysis (CIMMS). The red lines indicate strong shear - typically the “enemy” of tropical systems: