ATL: INVEST 90L - Discussion

[HURRICANELONNY]

Dr. Masters says possibly no future for 90L due to shear and neg. phase of the MJO.

New tropical wave 90L emerges from the African coast
A well-organized tropical wave (designated 90L by NHC on Thursday morning) has emerged from the coast of Africa, and is moving to the west at about 15 mph. Satellite images show the wave has plenty of spin, but little heavy thunderstorm activity. Wind shear is moderate, 10 - 20 knots, and the ocean temperatures are warm, near 28°C (82°F.) The core of the wave will pass a few hundred miles south of the Cape Verde Islands on Friday. Two of our three reliable computer models for predicting tropical storm formation show development by Monday, and in their 8 am EDT Wednesday Tropical Weather Outlook, NHC gave the system 2-day and 5-day odd of development odds of 10% and 40%, respectively. The Thursday morning long-range runs of the GFS and European ensemble models favored the storm taking a more west-northwesterly track into the open ocean next week, with a low threat to the Lesser Antilles Islands indicated. The Atlantic is expected to be dominated by dry, sinking air next week, due to the phase of the Madden Julian Oscillation (MJO), a pattern of increased thunderstorm activity near the Equator that moves around the globe in 30 - 60 days, so I expect that 90L will struggle to develop. Indeed, the 2 am EDT Thursday run of the SHIPS model showed 90L encountering increasingly dry air over the next five days in the face of moderate wind shear--conditions hostile for development.

[Nimbus]

Even in the Infared imagery you can see the outflow spreading uniformly.
Must be under a high pressure dome?
With the current conditions I wouldn't blame the NHC if they pulled the trigger early.
Looks about 13 degrees latitude so it may not follow this summers pattern of clinging to the ITCZ all the way to the islands.

If the models have strong mid atlantic ridging out near 45 degrees longitude you would think there might be a better chance for a recurve by 80 degrees. Models are not random this far out but pretty much still just gambling.

[gatorcane]

NHC Floater just updated and I provided the IR loop below - convection continues to increase quite dramatically. We may see development chances go up some on the next TWO which the NHC will issue at 8pm EST if this continues:

[HURRICANELONNY]

Wow. You can sure see in that loop 90L fighting the dry air surrounding it. Mabe it can hold on and find some moisture down the road.

[hurricanes1234]

Knowing what has happened to previous waves, I am not yet thinking this will develop. But that's just my opinion.

[Hammy]

I'm very skeptical with the models tending to overdevelop things in the MDR the last few years, and with the dry conditions, but I haven't the 'ball and tail' pattern with the ITCZ feeding into it with anything off Africa so far this year.

[gatorcane]

20% for first 48 hours up from 10% and removed wording "development, if any" and back to "some slow development...is possible:"

A tropical wave accompanied by a broad area of low pressure located
a couple hundred miles east-southeast of the Cape Verde Islands is
producing disorganized shower and thunderstorm activity. Some slow
development of this disturbance is possible over the next several
days while it moves westward at about 15 mph. Regardless of
development, this system could bring heavy rain and gusty winds in
squalls to portions of the Cape Verde Islands tonight and Friday.
* Formation chance through 48 hours...low...20 percent.
* Formation chance through 5 days...medium...30 percent

[MGC]

90L faces long odds IMO. Atlantic is bone dry all the way to the islands. We have seen how disturbances have fared on their trip across the Atlantic this season. 90L might do better one in the western Carb Sea. I am keeping an eye on the GOM and NW Carb but UL conditions are not good currently. Lets hope the season stays quiet....MGC

[abajan]

Let's see how it affects the Cape Verde islands over the next day or so:

http://weather.noaa.gov/weather/current/GVAC.html

Seems to be pretty windy there already.

[YoshiMike]

This thing is starting to look good

[gatorcane]

Latest IR rainbow floater, just updated by NHC...looking quite good, I wonder if we will get an ASCAT pass on this?

[YoshiMike]

ASCAT?

[Hammy]

ASCAT?

Looks like there should be a pass within the next few hours.

[gatorcane]

ASCAT?

It stands for Advanced Scatterometer. Basically when the ASCAT "pass" is done, we get an image that gives us an idea of what the low-level windflow is under these blobs of convection like we have with 90l. This let's us determine how well-defined the center is. You can read more about it here:

http://manati.star.nesdis.noaa.gov/products.php

[Rail Dawg]

I'm going contrarian.

This thing is going to develop into a TD quickly.

[TheStormExpert]

If the model guidance are correct 90L should be a TS in about 48hrs.

[Hammy]

NRL site (satellite every 15 mins) shows shrinking and warming cloud tops, so it looks like it's starting to feel the effects of the dry air (and a bad sign when looking for development, considering it's close to Dmax there).

[YoshiMike]

I'm going contrarian.

This thing is going to develop into a TD quickly.

I do too actually.

[Javlin]

90L faces long odds IMO. Atlantic is bone dry all the way to the islands. We have seen how disturbances have fared on their trip across the Atlantic this season. 90L might do better one in the western Carb Sea. I am keeping an eye on the GOM and NW Carb but UL conditions are not good currently. Lets hope the season stays quiet....MGC

I am with you MGC not much of the Cape season has produced anything as of yet;maybe/if it makes it to the islands then a more serious look at things might be required.

[Hurricaneman]

If something can survive until 50W this will IMO have a much better chance at development especially if the anticyclone and wave stay with eachother

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