By Dr Jeff Masters From Weather Underground

Satellite images on Monday morning showed that the moderate level of heavy thunderstorm activity associated with a large tropical wave passing through the Lesser Antilles Islands (Invest 92L) had changed little since Sunday. 92L brought winds near tropical storm-force to the Lesser Antilles on Sunday night, according to data from the ASCAT satellite. No rotation of the storm’s echoes was apparent on Martinique radar, though. The wave is fighting a large amount of dry air, which is keeping heavy thunderstorm activity relatively sparse.

A strong and persistent ridge of high pressure should keep 92L on a west to west-northwest path, and the system will be near Jamaica by Wednesday and approach the western tip of Cuba and Mexico’s Yucatan Peninsula by Thursday night. If 92L does develop, it probably won’t last long. The 8 am EDT Monday SHIPS model forecast for 92L showed light to moderate wind shear of 5 – 15 knots through Tuesday, rising to the high range, 20 – 25 knots, for the latter part of the week. The latest 0Z Monday operational runs of our three top models for forecasting tropical cyclone genesis–the GFS, European and UKMET models–did not show development of the system over the next five days. Almost all of the ensemble members of the 0Z Monday runs of the GFS and European model that did develop 92L showed the storm being destroyed by high wind shear and dry air before reaching Jamaica on Wednesday. In their 8 am EDT Monday Tropical Weather Outlook, NHC dropped their 2-day and 5-day development odds to 10% and 20%, respectively.

New African tropical wave may develop late this week
A tropical wave expected to leave the coast of Africa on Tuesday could develop into a tropical depression by next weekend, a few hundred miles west-southwest of the Cabo Verde Islands, predicted the 00Z Monday runs of the UKMET and European models. The Sahara Desert dust and dry air machine will be moderately active during the week, and development of this new tropical wave will likely be hindered by dry air. In their 8 am EDT Monday Tropical Weather Outlook, NHC gave this future system 2-day and 5-day development odds of 0% and 20%, respectively. The long-range models are showing a west-northwesterly track for this storm into the Central Atlantic to a location where few storms ever become a threat to the Lesser Antilles Islands.

IMAGE: Figure 2. Visible satellite image of Invest 92L at 1500Z (11:00 am EDT) Monday, September 5, 2016. Image credit: CIMSS/SSEC/University of Wisconsin-Madison.

For more on this story go to: https://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=3418

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“Talking the Tropics With Mike”: Tropical wave entering the Caribbean – Sept. 4th

By Michael Buresh From CBS47 FOX30

WE’RE APPROACHING THE PEAK OF THE HURRICANE SEASON. You should always be prepared & aware.

A tropical wave that came off the coast of Africa last weekend is speeding into the Eastern Caribbean. This wave struggled with a lot of dry air initially but has started to come to life – something to keep an eye on for next week through next week with increasingly favorable conditions over the far Western Caribbean &/or Western Gulf of Mexico — lessening shear though still rather dry. Virtually no models, however, develop this wave as of the moment. The wave will move through the Caribbean staying well south of Florida gently curving northwest eventually across the Yucatan Peninsula & perhaps into the Western Gulf of Mexico.

Water vapor imagery below shows a lot of dry air over the Central Atlantic which could interrupt development — for a while — of waves moving west off Africa….. pretty good dose of dry air over parts of the Caribbean & Gulf of Mexico as well.

Wind shear (red lines represent strongest shear). Strong shear has arrested the development of the wave approaching the Eastern Caribbean stretching out the wave west to east. Once west of this shear axis, organization of the wave will be possible (despite models not catching on to anything right now).

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. At least the first half of September is looking busy for the Atlantic Basin & it’s within the realm of possibility that at least two named storms could make U.S. landfall between now & mid to late Sept. (“Hermine” the first). Global models have — for now — slowed the development of the wave not to mention — no surprise (!) — shown a lack of any real consistency. Lots of dry air will likely limit much development until at least about two-thirds across the Atlantic Ocean. Moral of the story: don’t snooze on these waves! Some forecast models show a powerful hurricane later next week near or over the SW Atlantic — something to keep an eye on but certainly nothing to really “jump on” for right now given how far out from now that would be. I would not be surprised, however, to see multiple named storms next week &/or the week after over the Atlantic Basin (Atlantic Ocean/Caribbean/Gulf of Mexico).

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.

IMAGES:
Gulf of Mexico:
East Atlantic:
Computer models
NHC

For more on this story go to: http://www.actionnewsjax.com/weather/talking-tropics/talking-the-tropics-with-mike-tropical-wave-entering-the-caribbean-sept-4th/436935916