Talking the Tropics With Mike: Subtropical depression #4 forms over the W. Atlantic

No threat to land .... Saharan dust continues to dominate much of the Atlantic

Talking the Tropics With Mike: Subtropical depression #4 forms over the W. Atlantic

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We’ve managed to get subtropical (not purely tropical/warm core) depression #4 to form over the W. Atlantic. The system will move northeast & is no threat to any land areas while moving into the N. Atlantic.

Thunderstorm activity is active over the Western Gulf of Mexico in association with an upper level trough but no surface (low pressure) development is expected.... at least in the short term.

Meanwhile... a massive cloud of Saharan dust (5th image below) is over the Central & Eastern Atlantic spreading westward over the Caribbean. Such large dust clouds are quite typical for June & July & is indicative of generally dry mid & upper level air which usually inhibits tropical development. However, I’ve seen tropical systems thrive just outside the dust cloud ... or once away from the dusty atmosphere (see 2004)... so it’s not a “shoe in” that there will be no tropical development just because a lot of dust exists. Other factors have to be considered such as the overall shear values across the Atlantic Basin, general vertical motion values & sea surface temps. which are nowhere near their seasonal peak yet.


Atlantic dust:

The image below is from Paul Norton & shows the skies over Puerto Rico Mon., 06/22 filled with dust from Africa:

2020 names..... “Dolly” is next on the Atlantic list (names are picked at random by the World Meteorological Organization... repeat every 6 years... historic storms are retired (Florence & Michael last year) & Dorian is certain to be retired from the ’19 list....


East Atlantic:


Mid & upper level wind shear (enemy of tropical cyclones) analysis (CIMMS). The red lines indicate strong shear of which there is plenty across most of the Atlantic at the moment:

Water vapor imagery (dark blue indicates dry air):

Deep oceanic heat content is extreme over the NW Caribbean:

Sea surface temp. anomalies:

SE U.S. surface map:

Surface analysis centered on the tropical Atlantic:

Surface analysis of the Gulf:

Caribbean:

Global tropical activity: