Talking the Tropics With Mike: Wave near Fl. now tropical storm Gordon - stays far from Jacksonville

Sept. 3, 2018 — The "Buresh Bottom Line": Always be prepared!.....First Alert Hurricane Survival Guide... City of Jacksonville Preparedness Guide... Georgia Hurricane Guide.

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Local - Jacksonville/NE Fl./SE Ga - No impacts from Gordon or any other tropical systems Labor Day & through the week ahead (but there still will be some rain, heavy at times along with a moderate to high rip current risk at area beaches)...... & while heavy rain, gusty winds & a couple of waterspouts/isolated tornadoes will affect the Keys & S. Florida into Mon. night, no widespread damage is likely to occur. Tropical storm WARNINGS are in effect for the Keys, S. Fl. & coastal Louisiana, Mississippi & Alabama.

The circulation of "Gordon" improved dramatically early Monday as shown in radar loop below (S. Fl. Water Management District):

Tropical wave '91-L' has become tropical storm "Gordon" - banding of showers & t'storms intensified & organized overnight/early Mon. leading to an upgrade even before hurricane hunter aircraft investigate the storm.  The European model definitely wins the forecast model on this one & has stabilized on a weak tropical cyclone moving away from Florida to near New Orleans by Tue. night.  If the wave gets farther west over the Gulf (as indicated by the UKMET model) - vs. coming inland near New Orleans - conditions look to be more favorable for more substantial strengthening - less shear + more time over warm ocean.  The GFS model shows a very weak system but with similar timing & location to the European model.  While the water is very warm, Gordon is rather fast moving as tropical cyclones go + shear is formidable over the Gulf of Mexico & won't change much thanks to a stagnant upper level pattern of high pressure near the U.S. east coast north of Jacksonville.  This makes exact intensity problematic but does make the track pretty straight forward - Central Gulf Coast.  But there is some chance that the upper high expands to the west which would make for more of a westward move upon approach to the Gulf Coast (as indicated by UKMET model).

So I see no changes to the local - Jacksonville/NE Fl./SE Ga. Labor Day forecast: warm/humid/breezy... onshore flow off the Atlantic... scattered to numerous bands/clusters of showers & storms.  There will be a moderate to high rip current risk at area beaches.


Red lines below (CIMSS) show the shear  - 25+ mph - over the Gulf of Mexico:

Tropical storm "Florence" continues over the E. Atlantic & a full recurve is not a sure thing.  Florence is moving swiftly west/northwest & will turn more northwest over the Central Atlantic then stall - or even move slowly west - as strong high pressure moves across the N. Atlantic late week.  The turn west/northwest &/or stall will be something to watch but indications are that the next upper level trough / surface cold front could then pick up the system again which would lead to a full recurvature, BUT the pause will be something to monitor & consider.  The European model shows a weaker tropical cyclone initially which would allow for farther west movement (with the trade winds) while the GFS model shows a sharper & complete recurvature to the north with a stronger tropical cyclone.  The UKMET model is in-between.  I'm not ready to fully bite on any of the scenarios but the slowing of the storm over the Central Atlantic later this week will be a crossroads after which will be the critical move north as Florence is picked up by the next upper level trough OR a miss by the trough which would lead to a storm with a higher potential to get farther west.  Plenty of time to see how things evolve with Florence.  It would seem to me that any direct impact on the U.S. is at least 8-12 days away & would be north of Jacksonville IF anywhere on the U.S. coast.

The well advertised Atlantic changes - regarding potential storm development - are underway & should continue into at least the middle of Sept. The uptick in activity coincides with a very persistent pattern of surface & upper level high pressure anchored over or near the N. Atlantic which implies lower pressures to the south (the ol' what goes up, must come down postulate).  The upper level map below from early Sunday shows a strong ridge of high pressure over the Eastern U.S.  This ridge will guide the tropical wave near the Southern Bahamas into the Gulf of Mexico & away from Fl. by midweek.  This upper level ridge will be critical the next few weeks as tropical cyclones & waves move westward across the Atlantic.  The orientation, position & strength of the ridge will help determine any possible hits on the Caribbean, U.S. &/or Mexico.  Combine this set-up with the approach of the peak of the season, less shear overall, warm ocean temps., lots of moisture & a MJO pulse, & you get an active period in the tropics/Atlantic Basin.

Also of concern.... another wave - possibly two - that will move off the coast of Africa during the next week or so.  Either or both of these waves will have the potential to move farther west over the Atlantic as high pressure tries to assert itself across parts of the Central/Northern Atlantic.  Just how strong the Bermuda high is - or is not - will go a long ways in determining whether or not waves/tropical cyclones can move all the way across the Atlantic.

The map below shows - in simplest terms - rising (green) & sinking (brown) air (related to the MJO).  The green areas - in the tropics - are more favorable for tropical development & this kind of pattern is likely to overspread the Atlantic Basin in the coming weeks.



Florence followed by a strong tropical wave:

Mid & upper level wind shear (enemy of tropical cyclones) analysis (CIMMS). The red lines indicate strong shear......

The Atlantic Basin....


Gulf of Mexico:

Water vapor imagery (dark blue indicates dry air):

Deep oceanic heat content continues to increase over the Caribbean & Gulf of Mexico as one would expect now that we're in August.....

Sea surface temp. anomalies show a general recent warming over a good portion of the Atlantic Basin ....

SE U.S. surface map:

Surface analysis centered on the tropical Atlantic:

Surface analysis of the Gulf:


The E. Pacific remains a busy basin.  Triplets are spread out between Hawaii & Mexico: Miriam (left in the imagery below) is turning sharply north & will weaken while hurricane Norman moves west... & Olivia west of Mexico moves westward.  All will stay over open water through the weekend though Norman will be a northeast of Hawaii by midweek though at least several hundred miles away as it stands now.



In the W. Pacific.... once super typhoon "Jebi" is forecast to hit & affect Japan through Wed at Cat. 1 or Cat. 2 intensity - leading to heavy rain, strong winds & rough seas.