Talking the Tropics With Mike: Strong tropical wave speeds into the Caribbean

Tropical storm WARNINGS for Puerto Rico, Hispaniola & parts of Bahamas

Talking the Tropics With Mike: Strong tropical wave speeds into the Caribbean

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*** All eyes on the strong tropical wave/low pressure - ‘92-L’ / “Potential Tropical Cyclone Nine” speeding west into the Eastern Caribbean - still unclear exactly how this scenario will unfold but some impacts to Fl. are possible over the weekend into early next week - stay up to date.

LOCAL JACKSONVILLE:

Indications are that the system will be very near Fl. by late in the weekend/early next week but - as it looks right now - not very strong. If true, primary local impacts for Jacksonville/NE Fl./SE Ga. would be heavy rain & perhaps gusty winds along with rip currents at area beaches. All, of course, predicated on the exact location & strength. ***

I cannot emphasize enough that’s very early “in the game” on this system. There will almost certainly be changes to the track, intensity & impacts.

There have been numerous measured wind gusts near the Windward Islands near or above tropical storm strength (39 mph) + very strong convection + some indications of better outflow “over the top”, so it may not be long before we an official upgrade to a tropical storm (”Isaias”). Hurricane hunter recon will investigate the system frequently this week.

The ultimate track will likely hinge on two things:

(1) the Bermuda high to the north which is broad & strong.

(2) intensity. Weaker - will be more west with a slower turn more northward.... stronger - more north earlier. It’s possible that Puerto Rico & Hispaniola may also have a “say” if there’s any land interaction. The terrain of Hispaniola is very mountainous with peaks above 5,000 feet. A direct passage over the island would likely seriously disrupt the system. There may also be eventual interaction with Cuba.

It’s hard to ignore the constant fast west movement. The poorly defined center will likely jump around some until & unless it can become couched under the strong convection. This thing can’t turn on a dime when moving 20+ mph. The wave should slow as it nears the edge of the upper level ridge Thu./Fri. So... it seems to me the bulk of the wave will stay south of Puerto Rico & possibly just catch - or even miss - Haiti &/or the Dominican Republic. The wave should then move near or over Cuba on its turn northward to either Florida or even the Eastern Gulf of Mexico.

Forecast models - no surprise - have been & continue to be at odds with one another & sometimes at odds with themselves (from one cycle run to the next). It’s way too early to get too caught up in single model runs or to start to panic(!).

The European model seems to have settled on bringing a weak tropical cyclone to near S. Florida &/or the Eastern Gulf over the weekend... the GFS is now relatively similar though more east in the long run which has been a consistent bias so far... & the UKMET is between the two but has trended toward the European with a weaker tropical cyclone (had been indicating a strong hurricane at times) in the vicinity of Fl. over the by the weekend.

Overall forecast models recently have generally trended north & still insist on a northward move soon. Stronger/earlier development would tend to support a more northward track solution. There is a good deal of shear (6th image below) in the vicinity of the wave now - on the order of 25-30+ mph - but the shear decreases the more west it goes (until shear increases over/near the Gulf). There is also some dry air (7th image below) that may occasionally infiltrate the system when/if it organizes.

Current shear:

Dry air:

E. Atlantic tropical wave/disturbance spaghetti plots:


Atlantic dust continues to spill west off of the Saharan desert over the E. Atlantic. Tropical waves continue to “fester” along the south edge of the dust & have the potential to thrive once away from the dust.

2020 names..... “Isaias” 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: