Talking the Tropics With Mike: Tropical depression #13 forms.... + T.S. Jerry & Karen

Sept. 22, 2019 — The "Buresh Bottom Line": Always be prepared!.....First Alert Hurricane Survival Guide... City of Jacksonville Preparedness Guide... Georgia Hurricane Guide.  

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*** Though the Atlantic remains active, there are no immediate threats to Jacksonville/NE Fl. & SE Ga. or most of the coastal U.S.  Dangerous rip currents will continue at area beaches along with rough seas & surf due to a combination of distant tropical cyclones & persistent onshore flow.

BUSY ATLANTIC BASIN:

(1) Jerry over the Central Atlantic

(2) tropical storm Karen over the Caribbean

(3) t.d. #13 soon to be "Lorenzo"

The positioning & strength of the Bermuda high over the Atlantic plus an incoming upper level trough over the Northeast U.S. is again (like Dorian & Humberto) playing an important role in the track of tropical systems.  Jerry will follow Humberto's lead & move north then northeast across the Central Atlantic.  While Karen will initially follow suit, there are hints that high pressure will build north of Karen before the storm can escape out over the Atlantic.

By Monday - at about 30-35,000 feet - there was a weakening trough will be over New England while the Bermuda high shifted some to the east.  This essentially left an alleyway over Fl. giving Jerry an "out" well to the east of Fl.

JERRY:

T.D. #10 formed from an African tropical wave & was upgraded to a depression Tue. morning & the 10th tropical storm of the season early Wed. & then to a hurricane Thu. morning while moving steadily west/northwest.  Jerry has reached a zone of high shear, so the tropical cyclone has weakened & is clearly struggling.  Jerry will have no significant impacts on the Greater Antilles or Puerto Rico.   Early in the week, Jerry turns sharply northward then northeast following the "wake" of Humberto & the persistent weakness over the Western Atlantic staying east of the Bahamas & far to the east of the U.S. coast.  Current projections are for Jerry to be a good 1,000 miles east of Jacksonville late Monday.

Bermuda may again be impacted by a tropical storm or even a hurricane by Tue./Wed. as Jerry moves into an area more favorable for intensification upon the turn north then northeastward.

TROPICAL STORM KAREN:

Tropical storm Karen was upgraded early Sunday over the Eastern Caribbean.  Though showers & t'storms are numerous, the system is poorly organized overall owing to strong shear & a good deal of dry air. Tropical storm WARNINGS are in effect for several islands & a tropical storm WATCH has been issued for Puerto Rico & the U.S. Virgin Islands.  Lots to consider regarding Karen & its future.  Conditions continue to look marginal - at best - over the Eastern Caribbean for much intensification as the storm moves slowly northward. In fact, it's possible that Karen will degenerate into a depression or even an open wave.  Once north of the islands late in the week, Karen - if it's a "thing" will be at the ol' "crossroads" that I so often refer to - a move north or a turn west.  The European model has suddenly shifted far to the west & is quite robust.  The GFS model is also west but appears to be tied to a weak system steered by the prevailing easterlies.  The UKMET model is maintaining a northward heading over the open Atlantic, but the UKMET has not had a great season so far this year.

It does seem to me that the models are having a difficult time resolving all the low pressure  - lowering pressures overall - over the SW Atlantic / Caribbean &/or Gulf of Mexico.  So forecasts are likely to change & it will be a while before the models have any kind of handle on the situation.   So the moral of the story is: be prepared for changes.  Which seems logical, but I'm constantly reminded that logical doesn't always work.

Heads up! - Caribbean Islands, Bahamas, Gulf of Mexico & possibly eventually the U.S.

Spaghetti plots for Karen:

Ensemble plots for Karen:

EAST ATLANTIC TROPICAL WAVE, NOW T.D. #13:

A large/impressive tropical wave has come off the coast of Africa & has become t.d. #13 - soon to be "Lorenzo" -  over the E. Atlantic.  Heavy rain & gusty winds will affect the Cape Verde Islands through Tue.  All indications are that t.d. #13 will be an early turn to the north staying over the Eastern & Central Atlantic.

An examination of dust over the Atlantic shows generally less dust over the basin vs. past months which is fairly typical for September & the peak of the hurricane season. Much too much is made of the dust & tropical cyclones.  It's not all uncommon for tropical waves to simply "wait out" the dry air & dust organizing once the wave is clear of the dry atmosphere.

2019 names..... "Lorenzo" is next on the Atlantic list (names are picked at random... repeat every 6 years... historic storms are retired (Florence & Michael last year) & Dorian is almost certain to be next:

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 the Atlantic at the moment:

The Atlantic Basin:

Water vapor imagery (dark blue indicates dry air):

Deep oceanic heat content:

Sea surface temp. anomalies show a warm Gulf of Mexico, Central & Northwest Atlantic while the "Main Development Region" (MDR) remain cooler than avg.  Note the upwelling (cooler water) left behind Dorian near the Bahamas (though starting to "mix out"):

While the MDR is cooler than avg., it's important to realize the water is still warm enough to support tropical systems....

SE U.S. surface map:

Surface analysis centered on the tropical Atlantic:

Surface analysis of the Gulf:

Caribbean:

You will see me fairly often refer to the "Velocity Potential Anomalies" - usually in stride with the Madden-Julian Oscillation (MJO).  In simplest terms, the green lines correlate with rising air which can help lead to conditions favorable for tropical cyclone development.  And such is the case as a very strong "pulse" of rising air spread from the Pacific into the Atlantic Basin.  & right on cue - 3 named storms over the E. Pacific & now 2 named storms over the Atlantic.  This pattern of the MJO implies an active period over the Atlantic that may very well continue into the first 10 days of Oct.  Realize active does not necessarily mean "bad" - as in landfalling.  Track will come down to the orientation of the jet stream, Bermuda high & other large & even small scale weather features that will ultimately steer the tropical cyclones.  Bottom line: stay up to date on what's going in the tropics!

Humberto & Jerry over the Atlantic (+ Imelda remnants).... Kiko, Mario & Lorena over the E. Pacific:

Lorena hit the SW coast of Mexico before moving back over warm water & re-intensifying. The storm has again interacted with land - the Baja Peninsula - & now the upper coast of Mexico.  Lorena will quickly weaken over land but some tropical moisture will surge into Arizona producing heavy rain & possible flooding through Tue.

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