Talking the Tropics With Mike: Meandering Tammy... low pressure SW Caribbean

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*** LOCAL (Jacksonville/NE Fl./SE Ga.) IMPACTS FROM THE TROPICS: None.

The Atlantic Basin Overview:

** Tammy is over the Southwest Atlantic...

** A couple of tropical waves are over the Central & Eastern Atlantic & moving west/northwest.

** Weak low pressure is over the Southwest Caribbean then move inland over Central America possibly becoming a tropical depression in the process.

A tropical wave/low pressure area - ‘94-L’ - was upgraded to tropical storm “Tammy” late Wed. & to a hurricane Fri. morning. Tammy is now moving north/northwest away from the Caribbean & will be over the SW Atlantic much of the upcoming week. Trailing bands of heavy showers & t’storms will continue over some of the Leeward & Windward Islands of the Caribbean into Monday.

The track beyond over the next 5-6 days remains muddled with various solutions amongst the forecast models including a good deal of run to run variability within themselves. There is an increasing probability that Tammy may be left behind by the upper level trough that will move across the N. Atlantic. If so, then Tammy would languish over the Southwest &/or Central Atlantic north of the Caribbean for a number of days. Some turn toward the west may occur by mid to late week. The European model has been the most adamant on this possibility but shows a very weak system by the weekend. The GFS on the other hand has had a tendency to take Tammy northeast over the open Atlantic but has varied on just how fast that might happen.

In any case... other than an easterly swell along the east coast this week augmented by onshore flow & astronomically high tides, there will be no direct impacts to the U.S.

Additional spaghetti plots for Tammy:

‘95-L’:

The upper oceanic heat content (UOHC) [tropical cyclone heat potential/TCHP] across the SW Atlantic, Gulf & Caribbean:

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

October tropical cyclone origins:

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

Wind shear:

Saharan dust spreads west each year from Africa 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 impede 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 plume then try to develop if other conditions are favorable. In my personal opinion, way too much is made 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.

2023 names..... “Vince” 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 & Laura, Eta & Iota in ‘20, Ida in ‘21 & Fiona & Ian in ‘22]). In fact, this year’s list of names is rather infamous with “Katrina”, “Rita” & “Wilma” retired from the ‘05 list & “Harvey”, “Irma”,“Maria” & “Nate” from the ‘17 list. 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 *.

East Atlantic:

Mid & upper level wind shear (enemy of tropical cyclones) analysis (CIMMS). The red lines indicate strong shear:

Water vapor imagery (dark blue indicates dry air):

Deep oceanic heat content over the Gulf, Caribbean & deep tropical Atlantic. The brighter colors are expanding dramatically as we near the peak of the hurricane season.: