Talking the Tropics With Mike: Philippe moving slowly closely followed by strong tropical wave

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*** LOCAL (Jacksonville/NE Fl./SE Ga.) IMPACTS FROM THE TROPICS: None. We will see increasing seas & surf through the weekend due to strong onshore flow causing some minor to moderate flooding at time of high tide along the coast, intracoastal, St. Johns River & its tributaries.

The Atlantic Basin Overview:

** Tropical depression #17 formed over the Eastern Atlantic Sat. morning & was upgraded to tropical storm “Philippe” late in the afternoon...

** A strong tropical wave at a lower latitude & just to the southeast of Philippe has a good chance to become t.d. #18 then “Rina” while moving west/northwest...

** A trough of low pressure will develop off the east coast of Fl. by late week enhancing onshore flow but any significant surface low development appears unlikely at this time.

(1) A strong tropical wave - ‘90-L’ was upgraded to tropical depression #17 midday Saturday over the Eastern Atlantic then to tropical storm “Philippe”, the 16th named storm of the busy ‘23 hurricane season. Philippe is struggling against strong shear out of the west & southwest + some dry air. It now appears Philippe will be weak enough to eventually be steered by the low level trade winds turning the system west, even southwest by the weekend. There’s some chance there will be impacts to Puerto Rico & the nearby islands over the weekend, but Philippe is expected to be weak at that point, possibly little more than a trough of low pressure or weak tropical wave. Still... there may be some gusty winds & an uptick in showers & t’storms for Puerto Rico & other parts of the Greater Antilles over the weekend into early next week.

Philippe’s poorly defined center will likely jump around some as convection waxes & wanes. Forecast models are struggling with the movement & intensity of Philippe as well as possible interaction with the strong tropical wave just to the southeast. In fact, at times it’s difficult to discern much difference between Philippe & the tropical wave, so there may already be some interaction. Eventually - one will “win out” & likely become the dominant system.

There seem to be two likely outcomes: (1) Philippe stays weak & drifts to the west... or intensifies & turns rather sharply to the north.

(2) A strong tropical wave - ‘91-L’ has come off the coast of Africa over the weekend & has the potential to develop into a tropical cyclone - “Rina” over the next few days. Early indications are another system that turns to the north rather early over the Central Atlantic. More significant development may wait to occur until (& unless) there’s more separation between 91-L & Philippe to the northwest.

Check out the upper oceanic heat content (UOHC) [tropical cyclone heat potential/TCHP] across the SW Atlantic, Gulf & Caribbean. The warmth is very deep. But keep in mind warm ocean temps. alone doesn’t necessarily equate to a “big” hurricane season (need other ingredients & factors to be favorable too) but it’s obvious there is a lot of very warm water at great depths over the Caribbean & Gulf of Mexico stretching eastward all the way into the Central Atlantic:

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

July tropical cyclone origins:

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

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..... “Rina” 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.:

Sea surface temp. anomalies:

SE U.S. surface map:

Surface analysis centered on the tropical Atlantic:

Surface analysis of the Gulf:

Caribbean:

Atlantic Basin wave period forecast for 24, 48, 72 & 96 hours respectively:

East/Central Pacific:

West Pacific:

Global tropical activity: