ATL: INVEST 91L - Discussion

[cycloneye]

Post away for Tropical Wave SW of CV Islands.

AL, 91, 2015100412, , BEST, 0, 105N, 278W, 25, 1010, LO,

Thread at Talking Tropics forum that was the topic for this area.

viewtopic.php?f=31&t=117624&hilit=&p=2485016#p2485016

A broad low pressure area located several hundred miles southwest
of the Cape Verde Islands is producing a large area of disorganized
showers and thunderstorms. Upper-level winds are not particularly
conducive for tropical cyclone formation and any development of this
system should be slow to occur during the next several days while it
moves west-northwestward at 10 to 15 mph.
* Formation chance through 48 hours...low...10 percent
* Formation chance through 5 days...low...30 percent

[gatorcane]

We have a stretched vorticity at the moment. Lot's of convection, shear still around though. ECMWF not developing while the GFS (00Z run) shows some possible development down the road as it recurves north of the Leewards

[windnrain]

This one look like another out to sea type storm?

[cycloneye]

This one look like another out to sea type storm?

Unless a big subtropical ridge establishes it will evade the Caribbean islands. However,maybe some rain arrives being so large the moisture envelop even if it goes NW.

[gatorcane]

Quite an impressive wave. To put the size of it in perspective:

[gatorcane]

This is a very large system (looks like a monsoon-gyre-like, so future track will depend on where the actual low consolidates). I am seeing some pretty could spin towards the SW area of this blob at the moment. (9N, 42W) and looks to be heading W or WSW:

[Gustywind]

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN OCT 04 2015

A PAIR OF TROPICAL WAVES OVER THE E CENTRAL ATLC HAVE MERGED
THIS MORNING WITH THE PRIMARY AXIS EXTENDING FROM 20N35W TO LOW
PRES NEAR 10.5N38W 1010 MB. PLENTIFUL CONVECTION IS PRESENT WITH
THESE FEATURES WITH SCATTERED MODERATE FROM 07N-15N BETWEEN 31W-
44W...AND FROM 14N-18N BETWEEN 30W-35W. RECENT SCATTEROMETER
PASSES MISSED THE TROPICAL WAVE AND LOW...HOWEVER A RECENT
ALTIMETER PASS DID MEASURE SEAS TO 8 FT IN THE SE QUADRANT OF
THE LOW. ACCORDING TO THE LATEST GLOBAL MODEL GUIDANCE...THE LOW
IS FORECAST TO MOVE TO NEAR 14N43W WHILE WEAKENING BY 24 HOURS.

[cycloneye]

8 PM TWO:

A broad low pressure area located about midway between the Cape
Verde Islands and the Lesser Antilles is producing a large area of
disorganized showers and thunderstorms. Upper-level winds are not
particularly conducive for tropical cyclone formation, and any
development of this system should be slow to occur during the next
several days while it moves west-northwestward at about 15 mph.
* Formation chance through 48 hours...low...10 percent
* Formation chance through 5 days...low...30 percent

[Gustywind]

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN OCT 04 2015


...TROPICAL WAVES...

A TROPICAL WAVE IS OVER THE CENTRAL ATLC WITH AN AXIS EXTENDING
FROM 21N35W TO 10N40W WHERE THERE IS A 1010 MB SURFACE LOW. THIS
WAVE COINCIDES WITH A 700 MB TROUGH BETWEEN 34W AND 43W...AND A
850 MB MAXIMUM OF VORTICITY NEAR 12N30W. THIS WAVE IS EMBEDDED
IN AN ENVIRONMENT OF MODERATE TO HIGH MOISTURE AND HAS
DIFFLUENT FLOW ALOFT. NUMEROUS MODERATE CONVECTION IS FROM 10N
TO 14N BETWEEN 39W AND 42W. SCATTERED MODERATE CONVECTION IS
FROM 07N TO 16N BETWEEN 42W AND 46W.

[gatorcane]

Looking at the big picture this evening, the wave is certainly looking good still with a large area of disorganized convection. Looks to be heading west at a good clip still. Data from RAL shows 13knots for the 00Z update but seems faster to me. I see the models are shifting a little more to the west in response to the continued west movement.

[Sanibel]

See if it jells tomorrow.

[bahamaswx]

Certainly jelling overnight. Step 1: One big blob. Complete.

[Gustywind]

From Wundeground: http://www.wunderground.com/hurricane/a ... text=track

Time Lat Lon Wind(mph) Pressure Storm type
-------------------------------------------------------------
12 GMT 10/4/15 10.5N 27.8W 25 1010 Invest
12 GMT 10/4/15 10.6N 38.3W 25 1010 Invest
12 GMT 10/4/15 10.6N 38.3W 25 1010 Invest
12 GMT 10/4/15 10.6N 38.3W 25 1010 Invest
18 GMT 10/4/15 10.6N 39.7W 25 1010 Invest
00 GMT 10/5/15 10.8N 41.2W 25 1010 Invest
06 GMT 10/5/15 10.9N 42.6W 25 1010 Invest

[Gustywind]

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT MON OCT 05 2015



A TROPICAL WAVE IS OVER THE CENTRAL ATLANTIC WITH AN AXIS
EXTENDING FROM 20N38W TO A 1010 MB LOW CENTERED NEAR 10N42W.
THIS WAVE COINCIDES WITH A 700 MB TROUGH BETWEEN 36W-46W AND IT
IS EMBEDDED IN AN ENVIRONMENT OF MODERATE TO HIGH MOISTURE WITH
DIFFLUENT FLOW ALOFT. A CLUSTER OF MODERATE TO STRONG CONVECTION
IS FROM 10N-16N BETWEEN 40W-45W.

[AutoPenalti]

Looks terrible this morning.

[Gustywind]

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT MON OCT 05 2015


A TROPICAL WAVE IS OVER THE CENTRAL ATLANTIC WITH AN AXIS
EXTENDING FROM 20N39W TO A 1010 MB LOW CENTERED NEAR 10N43W.
THIS WAVE COINCIDES WITH A 700 MB TROUGH BETWEEN 40W-46W AND IT
IS EMBEDDED IN AN ENVIRONMENT OF MODERATE TO HIGH MOISTURE WITH
DIFFLUENT FLOW ALOFT. A CLUSTER OF MODERATE TO STRONG CONVECTION
IS FROM 11N-19N BETWEEN 41W-46W.

[Sanibel]

If it re-fires it's in a dangerous, low initial position at 10N.

[ScottNAtlanta]

It looks to me like the area to watch is on the SE side of 91L

[bahamaswx]

Certainly jelling overnight. Step 1: One big blob. Complete.

Step 2: Maintain giant blob....

[Sanibel]

There's nothing at their initialization location. There's a faint swirl near 45W-15N.


That follow-up disturbance looks like it has the better chance.