"Talking the Tropics With Mike": Tropical waves either side of Florida - Sept. 11th

Sept. 11, 2016 — This weekend -- specifically Sept. 10th -- marks the peak of the hurricane for the Atlantic Basin.  We have several areas of concern with the development of at least one new named system likely within the next several days.  While it appears a wave approaching the Bahamas & eventually Florida (Tue./Wed.) will have a tough time developing much, the wave should bring enhanced rainfall for much of Florida/SE Ga.

AT THE PEAK OF THE HURRICANE SEASON...  You should always be prepared & aware.  First Alert Hurricane Center ** here **.  Reminder that flood insurance policies take 30 days to take effect..... & will not be written when/if a named storm is nearby.

The weak area of low pressure (Invest 92L) that developed Fri. over the Florida Straits is slowly & somewhat erratically moving in a general westerly direction near a stalled frontal zone.  A good deal of northwest shear is pushing the convection to the south & east & should limit much development, especially in the short term.  Virtually none of the models develop much from this area of "disturbed" weather.  But this is a set-up I mentioned early Fri. -- watch out along old stalled fronts this time of year that are in the subtropics or near the tropics.  In any case... there will be no impacts on Jax/NE Fl./SE Ga.

Radar imagery below courtesy South Florida Water Management District:

A weak tropical wave (93L) continues moving west/northwest into the Bahamas.  The wave should steadily march W/NW but -- again -- models are not impressed.  The likely to be open wave (vs. a closed low pressure circulation) will approach Florida late Mon., crossing the state Tue./Wed. & should enhance rain for Florida including Jacksonville & surrounding areas early to mid week.  We will need to monitor this area closely for any sudden uptick in organization & persistence of the strongest convection.

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Water vapor imagery below shows the dry air over much of the Gulf of Mexico gradually moistening while dry air over the Caribbean & Central Atlantic slowly shrinks.

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Wind shear (red lines represent strongest shear).  Pockets of strong wind shear are scattered throughout the Atlantic Basin & are playing a role in keeping the waves east & west of Florida from organizing much.... with a large area of shear over the Central & Eastern Atlantic which is impacting (stretching out) the strong Central Atlantic wave.

Gulf of Mexico:

East Atlantic:

Satellite imagery centered on Africa & the far E. Atlantic shows tropical waves lined up across the E. Atlantic & Africa - pretty classic for this time of year.  September is looking busy for the Atlantic Basin though not so much within the next week.  Long range global forecast models have been inconsistent on development & movement - no surprise!

Meanwhile... the MJO -- Madden-Julian Oscillation -- was in a favorable state the last week to 10 days, but the pulse (2nd image below) has all but suddenly collapsed.  General rising air (green lines) often times favors tropical development..... especially when all other things (shear, moisture, etc) are equal.  Brown lines show general sinking air which has now spread across much of the Eastern Pacific & Western Atlantic Basin.  Such a state doesn't preclude tropical development, but the general sinking air could at least limit the number of systems that might try to develop.  We'll likely see some additional quick turn-arounds in the state of the rising/sinking air the rest of this month.

The call on a strong wave (Invest 94L) over the Central Atlantic is for a recurve to the north, but it could become a named storm.  This wave is poorly organized but is spread out over a large area.  The wave is battling strong shear to the immediate northwest which is evident on satellite imagery. Other waves -- all the way east to Africa -- will continue to march west with the potential for development.

Lots of warm water to help "feed" tropical cyclones.  Water temps. of 28 degrees Celsius equates to 82 degrees Fahrenheit.  Tropical cyclones generally need at least 80 degree water to thrive.

Sea surface temps. vs. average:

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Quick look at the Western Pacific.... Heads-up for Taiwan & surrounding areas as a developing typhoon - "Meranti" -  steadily marches W/NW with the potential for a significant hit on the island nation by midweek.

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