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Talking the Tropics With Mike: Barry slowly moving into Louisiana

July 13, 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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*** Tropical storm WARNING, storm surge WARNING & Hurricane WARNING coastal Louisiana.....

Barry is slowly advancing to the Louisiana coast.  There will be NO direct impacts for Jacksonville/NE Fl. & SE Ga.

The average date for the first Atlantic tropical system is July 9th, so we're about "on schedule".  The last two U.S. landfalling July tropical systems were tropical storm Emily in 2017 (Central Florida) and hurricane Arthur in 2014 (N. Carolina).

Upper level high pressure over the Western U.S. + a weaker upper level high pressure cell near Florida will allow for an alleyway of sorts along the Gulf Coast helping to induce a northward turn.  The position & strength of these upper level high pressure areas is the key to the ultimate turn north of "Barry" & just how far west the system may end up.

The landfall for Barry - as either a strong tropical storm or weak hurricane - will be through the day Saturday approximately 100 mileswest/southwest of New Orleans.  Extreme rainfall - 2 feet or more - is possible for parts of Louisiana & Mississippi. Major flooding is of great concern considering what has been a wet spring & early summer with already high levels on the Mississippi River & its tributaries.  Significant storm surge will occur over SE Louisiana & coastal Mississsippi & - to some degree - for coastal Alabama.  Barry has been battling some shear out of the north as well as some dry mid & upper level air being pulled into the circulation from the continental U.S., but conditions overall generally favor at least slow strengthening up to landfall.  Convective "bursts" (nearly nonstop t'storm development) has been ongoing since early Fri. over the southern half of the broad circulation.  The storms have had difficulty wrapping all the way around the center & proximity to land might impede that process.  But the nearly constant firing of thunderstorms is an indication that Barry is trying to organize and strengthen & probably will be trying to do so all the way up to landfall.

While the center of the storm will be well west of New Orleans, it's important not to get too caught up on exactly where the center is & is forecast to be.  Especially in the case of less well developed tropical cyclones like Barry, hazards extend far away from the center.  New Orleans will be in some of the bands of very heavy rainfall that will repeatedly move across the city.  While rainfall may ultimately be heaviest - 1-2 feet - a little west of New Orleans across the heart of Louisiana, serious flooding is still likely for New Orlenas given strong onshore flow off the ocean feeding into the city's waterways in combination with at least 6-12" of rain, possibly more.

Model plots:.

Sea surface temps. over the Gulf are plenty warm enough to support &/or help tropical development.... as highs as the upper 80s over parts of the Northern Gulf with particularly warm water temps. just about right where Barry is expected to track off the coast of Louisiana.

Rainfall forecast through the weekend is very heavy along the Gulf Coast closest to Barry with the potential for considerable flooding for New Orleans & much of Louisiana & Mississippi with very heavy rain as far north as the Ohio River.

Radar imagery courtesy S. Florida Water Management District:

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Dr. Phil Klotzbach, Colorado St. University produced the image below showing the Gulf is "sweet spot" for tropical development in July but - interestingly - no hurricane has had its genesis (formation) over the Gulf in July going back to 1851.  But - beware - there's a first time for everything & Barry is forecast to become a hurricane prior to landfall.

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2019 names..... "Andrea" was briefly upgraded in May.  Next on the list: "Barry" (names are picked at random... repeat every 6 years... historic storms are retired (Florence & Michael last year):

Atlantic Basin:

A weak wave is over the Eastern Atlantic but there does not seem to be much support for long term development....

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 some "cool" water remaining over the E. Atlantic but avg. to above avg. temps. for much of the rest of the Atlantic Basin.....

SE U.S. surface map:

Surface analysis centered on the tropical Atlantic:

Surface analysis of the Gulf:

Caribbean: