Talking the Tropics With Mike: Hanna weakening inland... all eyes on strong Atlantic tropical wave

Douglas moving over Hawaiian Islands while slowly weakening

Talking the Tropics With Mike: Hanna weakening inland... all eyes on strong Atlantic tropical wave

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*** No direct impacts from current systems in the tropics for Jacksonville/NE Fl./SE Ga. over the next 5-6 days ***

(1) the tropical wave/disturbance that’s been moving northwest across the Gulf of Mexico strengthened into tropical depression #8 Wed. evening & tropical storm Hanna Thu. evening & into the Atlantic season’s first hurricane early Saturday (avg. first Atlantic hurricane is Aug. 10). Hanna is the fastest ever to the ‘H’ name beating “Harvey” on Aug. 3, 2005. Hanna continued to organize right up to landfall at 6pm EDT at Padre Island followed by a second landfall on the Texas coast a couple of hours later as a strong Cat. 1 hurricane with sustained winds near 90 mph including an eye 20-25 miles across. Hanna is the 4th named storm for July which is just short of the record of 5 set in 2005. Two named storms over the Atlantic Basin at the same time in July last happened in 2018 (Beryl & Chris). Other times since 2000 (Klotzbach): 2011, 2008 & 2005. Hanna will now continue to weaken while moving W/SW over far Northern Mexico while still dropping torrential rain & isolated tornadoes.

(2) low pressure over the Central Atlantic became tropical depression #7 Tue. & then tropical storm “Gonzalo” Wed. This is the fastest ever to the 7th named storm over the Atlantic beating “Gert” in 2005 by two days. The avg. date of the 7th named storm is not until Sept. 16th. As expected a combination of dry air, shear & proximity to the S. American coast eventually destroyed the inner core of Gonzalo which is now an open wave & not anticipated to regenerate while moving westward toward Central America.

(3) Tropical waves continue rolling off the coast of Africa. One wave - 92L - in particular has potential to develop. Long range forecast models show a long track across the tropical Atlantic through early Aug. “underneath” the broad & strong Bermuda high. This one could be a “trouble maker” & the first classic tropical cyclone from the deep tropics of the season. Forecast models, of course, are 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 the modeling or to start to panic(!). The European has the system in the Western Caribbean by the weekend/early next weak & has trended much weaker & farther south with recent operational runs showing a move west through the Caribbean (although ensemble members indicate a potential northward move)... the GFS is faster & has the system east of Fl. by late in the upcoming week/weekend... & the UKMET is between the two on timing but much stronger indicating a hurricane north of Puerto Rico & close to the Bahamas by the weekend. Overall forecast models recently have generally trended north. Movement will ultimately hinge on the positioning & strength of the Bermuda high over the Atlantic & how quickly (or not) the wave develops. Stronger/earlier development would tend to support a more northward track solution. One to watch no doubt!

(4) A little upper level disturbance/trough of low pressure that was left behind from Hanna over the weekend is over the Northern Gulf of Mexico. While not particularly likely, it’s not out of the question, clusters of t’storms could fester with this disturbance helping to induce surface low pressure. IF so, this could be an area to watch for rather sudden/short term tropical development - anywhere from Louisiana to the Fl. Panhandle. Not a likely scenario but something to keep an eye on. The low/upper trough will then emerge over the Western Atlantic by the middle of next week where there could also be some potential for tropical development as the low rides on out northeast over the Atlantic. Forecast models are indicating virtually nothing at the moment.

Radar imagery courtesy South Florida Water Management District:

There has also been a rather persistent cluster of t’storms over/near the Bahamas tied to an upper level disturbance/old tropical wave that’s east of Jacksonville Sunday. No surface development is indicated or expected while the system moves north/northwest then more northward a little offshore through Sunday night/Monday. Some extra rain for coastal areas thanks to this feature.

Overall.... it looks like a much more active Atlantic into at least the first 10 days of Aug. More on that further down - see “Velocity Potential Anomalies”.

Gonzalo moved away from the dry air in the water vapor image below but little else was favorable (land & shear). The remnants have - & will continue - occasionally flare up with strong convection but should remain disorganized while heading for Central America. Strong westerly shear should keep the wave “in check”.


E. Atlantic tropical wave/disturbance spaghetti plots:

Meanwhile... “velocity potential anomalies” map below shows why we could - & should - see more tropical activity over both the E. Pacific & Atlantic in the coming weeks. The green lines indicate “upward” vertical velocities which are shown to be in a narrow but strong corridor spreading from the Eastern Pacific into the Atlantic Basini. This upward motion in the atmosphere often correlates with increased t’storm activity & sometimes tropical development & is right in concert with the development of tropical cyclone Douglas over the E. Pacific. I would expect to see at least a couple of named storms pop over the Atlantic Basin between now & August 10th & has likely already helped with the development of Hanna over the Gulf of Mexico.

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:


In the East Pacific.... “Douglas” became a powerful Cat. 4 hurricane over the East Pacific Thu. after rapidly intensifying but has peaked... is leveling off.... & will now gradually weaken. Douglas will move over & near the Hawaiian Islands & may still be a formidable tropical storm or even low end Cat. 1 hurricane with the eye projected to go north of the Big Island Sunday & very near Honolulu Sunday night/Monday. Hurricane WATCHES & WARNINGS + tropical storm WATCHES/WARNINGS are in effect.

Global tropical activity: