ATL: EDOUARD - Post-Tropical - Discussion

[blp]

Convection continuing to fire. The lower latitude is certainly helping it maintain convection. My take is it needs to form in the next 48hrs or it will hit the buzzsaw. Right now it looks like it will develop IMO.

http://www.ssd.noaa.gov/PS/TROP/floaters/91L/imagery/rb_lalo-animated.gif

[cycloneye]

This is the 06z Best Track:

91L INVEST 140908 0600 9.5N 19.6W ATL 25 1009

[Gustywind]

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT MON SEP 08 2014

...SPECIAL FEATURES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 18W/19W FROM 15N
SOUTHWARD...MOVING WESTWARD 10 TO 15 KNOTS. A 1009 MB LOW
PRESSURE CENTER IS ALONG THE WAVE NEAR 9N. BROAD MIDDLE LEVEL TO
UPPER LEVEL CYCLONIC WIND FLOW IS ON TOP OF THE AREA OF THE
TROPICAL WAVE. CONVECTIVE PRECIPITATION...NUMEROUS STRONG IN
SENEGAL AND GAMBIA FROM 12N TO 15N BETWEEN 14W AND 16W...AND
FROM 8N TO 10N BETWEEN 21W AND 23W IN THE ATLANTIC OCEAN.
SCATTERED MODERATE TO ISOLATED STRONG ELSEWHERE FROM 6N TO 13N
BETWEEN 18W AND 24W...AND FROM 5N TO 8N BETWEEN 26W AND 41W.
ISOLATED MODERATE FROM 5N TO 9N BETWEEN 48W AND 54W. THE CHANCE
THAT THIS FEATURE MAY DEVELOP INTO A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS IS MEDIUM.

[cycloneye]

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 AM EDT MON SEP 8 2014

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

A broad area of low pressure located a few hundred miles
south-southeast of the Cape Verde Islands is producing a large area
of cloudiness and disorganized thunderstorms. Environmental
conditions are forecast to be conducive for gradual development of
this disturbance during the next several days while it moves
westward or west-northwestward at about 15 mph.
* Formation chance through 48 hours...medium...30 percent.
* Formation chance through 5 days...high...60 percent.

$$
Forecaster Brown

[tolakram]

30 frame live visible: http://rammb.cira.colostate.edu/ramsdis/online/loop_meteosat.asp?data_folder=tropical/tropical_met_4km_visir2_floater&width=640&height=480&number_of_images_to_display=30

[wxman57]

91L doesn't look too impressive on visible imagery. Rotation is minimal compared to 90L in the top left of the image, but convection is greater in 91L. Will be interesting to see if the models continue to develop it if/when it fails to develop over the next couple of days. Will the dry mid-level air kill this one too?

[blp]

30 frame live visible: http://rammb.cira.colostate.edu/ramsdis/online/loop_meteosat.asp?data_folder=tropical/tropical_met_4km_visir2_floater&width=640&height=480&number_of_images_to_display=30

You can clearly see how this wave is tapping into the ITCZ for mosture. I certainly think this has the best shot of any of the recent waves we have seen this year.

[tolakram]

TPW loop seems to show a decent moisture envelope around 91L.

http://tropic.ssec.wisc.edu/real-time/mimic-tpw/natl/main.html

[cycloneye]

12z Best Track:

91L INVEST 140908 1200 9.9N 20.8W ATL 25 1009

[Alyono]

the models said this would be a named storm already

This is a pure modelcane, nothing more. Environmental conditions are simply not favorable

[Gustywind]

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT MON SEP 08 2014

...SPECIAL FEATURES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 19W/20W FROM 17N
SOUTHWARD...MOVING WESTWARD 10 TO 15 KNOTS. A 1009 MB LOW
PRESSURE CENTER IS ALONG THE WAVE NEAR 9.5N. BROAD MIDDLE LEVEL
TO UPPER LEVEL CYCLONIC WIND FLOW IS ON TOP OF THE AREA OF THE
TROPICAL WAVE. CONVECTIVE PRECIPITATION...SCATTERED STRONG FROM
7N TO 13N BETWEEN 21W AND 23W. THE CHANCE OF THIS FEATURE
DEVELOPING INTO A TROPICAL CYCLONE DURING THE NEXT 48 HOURS IS
MEDIUM.

[Gustywind]

From Accuweather

http://www.accuweather.com/en/weather-n ... l/33568706

Tropical Depression May Develop in Atlantic This Week

Jordan Root

By Jordan Root, Meteorologist

September 8, 2014; 8:43 AM ET

A robust tropical feature has emerged in the eastern Atlantic and could develop as the week progresses.

The feature, recently departing the coast of Africa and moving over open water, has a chance for development in the near future.

Strong winds will begin to relax across the eastern Atlantic during the week and will allow this wave to travel through a more suitable environment for strengthening.

According to AccuWeather Senior Meteorologist Bob Smerbeck, "It has a chance of organizing and strengthening as long as it stays far enough south and away from dry air and wind shear."

Wind shear is a fast flow of air well above the sea surface that can prevent tropical systems from developing or limit their strengthening.

Thus far there have been five tropical depressions in the Atlantic to date this year. Should the system develop a circulation, it would be the sixth tropical depression.

If the system manages to avoid wind shear and dry air to become a tropical storm, it would take on the name Edouard and would be the fifth named system in the Atlantic Basin.

Those with interests in the eastern Caribbean, Bahamas and Bermuda will want to monitor the organization and track of the tropical disturbance currently designated as 91L.

According to AccuWeather.com Hurricane Expert Dan Kottlowski, "91L will track to the west-northwest during the next week and may pass close to the Leeward Islands early next week."Steering winds are likely to cause 91L to take a curved path to the northwest, north then the northeast over the next 10 days. The path should keep the system away from land in the United States.

[Gustywind]

From Dr. Jeff Masters

African Wave 91L Worth Watching; Record Quiet Spell Ends in Western Pacific

http://www.wunderground.com/blog/JeffMa ... rynum=2790

A tropical wave (91L) that emerged from the coast of Africa on Sunday is headed west to west-northwest at about 15 mph. Satellite images show 91L has a moderate amount of spin and heavy thunderstorm activity, but these thunderstorms are poorly organized. The disturbance is embedded in a moist air mass, has moderately warm (SSTs) of 27.5°C (82°F) beneath it, and is experiencing light wind shear. These conditions favor development. The 8 am EDT Monday run of the SHIPS model predicted that wind shear would remain light to moderate ( 5 - 15 knots) for the next five days, favoring continued development. However, development will be slowed by the fact that the atmosphere at mid-levels of the atmosphere (between 500 - 700 mb) should grow steadily grow drier. Two of our three reliable computer models for predicting tropical storm formation predict development of 91L over the next five days. In their 8 am EDT Monday Tropical Weather Outlook, NHC gave the system 2-day and 5-day odd of development odds of 30% and 60%, respectively. A trough of low pressure expected to push off the U.S. East Coast early next week should induce a more northwesterly track for 91L next week, and the disturbance does not appear to be a long-range threat to the Lesser Antilles Islands. It remains to be seen if 91L will be a long-range threat to Bermuda, the U.S. East Coast, or the Canadian Maritime Provinces late next week.

[Riptide]

Sometimes you gotta dump the pessimism and be realistic...

the models said this would be a named storm already

This is a pure modelcane, nothing more. Environmental conditions are simply not favorable

[cycloneye]

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT MON SEP 8 2014

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

A broad area of low pressure located a few hundred miles
south-southeast of the Cape Verde Islands is producing a large area
of cloudiness and disorganized thunderstorms. Environmental
conditions are forecast to be conducive for gradual development of
this disturbance during the next several days while it moves
west-northwestward at about 15 mph.
* Formation chance through 48 hours...medium...30 percent.
* Formation chance through 5 days...high...60 percent.

$$
Forecaster Cangialosi

[gatorcane]

Looks like it is gradually getting a better structure to me. After what I am seeing fro the 12Z guidance, development chances are increasing. I am leaning towards this becoming a named system.

Maybe if we are lucky, this eventually becomes a major FISH out in the middle of the Atlantic....

[wxman57]

It does look a bit better now. I'd put a "center" around 12.5N/22.9W. Convection is weak, though. At that latitude, given the general weakness in the Azores-Bermuda high over the next week, I don't see this being a Caribbean or U.S. threat should it develop.

[cycloneye]

18z Best Track:

91L INVEST 140908 1800 10.4N 21.6W ATL 25 1009

[tolakram]

Live visible loop: http://rammb.cira.colostate.edu/ramsdis/online/loop_meteosat.asp?data_folder=tropical/tropical_met_4km_visir2_floater&width=640&height=480&number_of_images_to_display=21

source: http://rammb.cira.colostate.edu/ramsdis/online/tropical.asp

[TropicalAnalystwx13]

Chances continue to look good that this becomes Edouard over the coming days as shear remains light to moderate and the atmosphere remains reasonably moist.