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Talking the Tropics With Mike: Atlantic tropical wave up against shear & dry air

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Tropical wave - ‘97-L’ - continues to chug west over the Eastern Atlantic. See the satellite imagery below which shows the wave battling dry air. The Saharan dust has been prolific across much of the Atlantic during June/July/early Aug. - not at all uncommon. The dust is usually co-located with dry mid & upper level air that can slow or inhibit tropical development. But I’ve often seen waves that can thrive on the edges of the dust plume or once the wave exits the dust plume. Remember the dust is a product of the dry air not vice-versa.

The orange, red & pink shows the dry air over much of the Atlantic Basin:

‘97-L’ has been a classic African tropical wave once off the coast but conditions become more hostile by the weekend & beyond. The Bermuda high (clockwise circulation) - while expansive - is not as strong as past weeks so movement won’t be particularly fast to the west. The GFS model is rather robust early but then shows little more than an open wave by the weekend into next week over the SW Atlantic. The European model remains generally weak & therefore shows a more southern track that’s more directed by the low level trade winds. But either outcome is not significant in the long run. In other words, it would appear ‘97-L’ will not manage to become a significant tropical cyclone.

So it appears shear in particular - but also dry mid & upper level air - will work pretty strongly against ‘97-L’. Still - since the disturbance will be not too far from the Caribbean &/or SE U.S. in about a week or so, it’s something to keep a close eye on.

Spaghetti plots for ‘97-L’:

Averages based on climatology for the Atlantic Basin through Aug.:.

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, we’ve had several large dust plumes spread west to the Caribbean & Gulf with the peak of Saharan dust typically in June & July.

2022 names..... “Danielle” 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]). In fact, this year’s list of names is rather infamous with “Charley”, “Frances”, “Jeanne” & “Ivan” retired from the ‘04 list (all hit Fl.) & “Matthew” was retired in 2016. The WMO decided - beginning last year - 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:

Sea surface temp. anomalies:

SE U.S. surface map:

Surface analysis centered on the tropical Atlantic:

Surface analysis of the Gulf:

Caribbean:

GFS wave forecast at 48 & 72 hours (2 & 3 days):

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

Updated Atlantic seasonal forecast from early Aug. - NOAA & CSU:

The East Pacific:

“Howard” is well west & southwest of the Baja of California & is weakening. The tropical cyclone is turning more west as the trade winds become dominant as Howard weakens & the system becomes more shallow.

West Pacific:

Global tropical activity:


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