Tropical Wave about to emerge West Africa (Is Invest 92L)

[CYCLONE MIKE]

Already hinting at recurve bets 00z will. Pattern that it showed in 12z is special. So many many obsticals to overcome just to make the trek I sure wouldn't loose sleep over.

I know I won't be losing any sleep over the models for this one. They got me for 99, but not again.

[chaser1]

Here's a question regarding NHC TWO percentage consistancy if anyone can logically answer it for me. Does 30% mean "conditions appear favorable for development", or does 30% mean "...upper-level winds are not conducive for significant development..."??? NHC has lately been inconsistant with the use of a percentage of liklihood for development and both Pouch 25L and 99L at 2:00pm today each were assigned a 30% chance of development and yet for the time frame specified for each of them, the text indicated quite a different level of confidence regarding the prospect of development. If 30% suggests chances for one system's development are "low", than why suggest 30% for another tropical system mean the chance of development are "high"?

Wait, better yet -

Which would indicate a better chance for development???
A) "...any development of this system is expected to be slow to occur..." OR
B) "...conditions appear favorable for development..."

If your answer here was "B", than you're wrong. In the 8:00pm TWO, 99L was upgraded to a 40% (48hr.) and 50% (5 days) chance of development, yet the language used to describe this was actually Answer "A". Slow to occur doesnt sound all too confident to me, so why assign a percentage of likelyhood that infers something different. Meanwhile, "B" describes the 40% prospects that Pouch 25L will develop during the next 5 days.

[cycloneye]

Looks like already has a nice circulation.

 https://twitter.com/Adriansweather/status/769721701953187840

[Siker]

Here's a question regarding NHC TWO percentage consistancy if anyone can logically answer it for me. Does 30% mean "conditions appear favorable for development", or does 30% mean "...upper-level winds are not conducive for significant development..."??? NHC has lately been inconsistant with the use of a percentage of liklihood for development and both Pouch 25L and 99L at 2:00pm today each were assigned a 30% chance of development and yet for the time frame specified for each of them, the text indicated quite a different level of confidence regarding the prospect of development. If 30% suggests chances for one system's development are "low", than why suggest 30% for another tropical system mean the chance of development are "high"?

Wait, better yet -

Which would indicate a better chance for development???
A) "...any development of this system is expected to be slow to occur..." OR
B) "...conditions appear favorable for development..."

If your answer here was "B", than you're wrong. In the 8:00pm TWO, 99L was upgraded to a 40% (48hr.) and 50% (5 days) chance of development, yet the language used to describe this was actually Answer "A". Slow to occur doesnt sound all too confident to me, so why assign a percentage of likelyhood that infers something different. Meanwhile, "B" describes the 40% prospects that Pouch 25L will develop during the next 5 days.

Part of it is because 25L is still over Africa. It's pretty clear that this will develop at some point; this is as much model consensus as you get. That's really what "conducive for development" means, that conditions will be good but it only has a 48 hour period to develop in this 5 day window barring development over land, so there's not total confidence this will manage to develop within 5 days just because these waves often taken a few days to develop even if the environment is favorable.

[chaser1]

Siker, I fully agree with your point but then if I were writing the TWO and realized that (as an example) a tropical wave would take "4 days" to reach the coast, that there'd be little reason for me to more than mention it and perhaps tag it with a 10% or 20% chance of development. That's basically because I know it wont develop over land and how great could the chances be of it developing in that final 24 hours of the present 5 day outlook?

[Hurricaneman]

Siker, I fully agree with your point but then if I were writing the TWO and realized that (as an example) a tropical wave would take "4 days" to reach the coast, that there'd be little reason for me to more than mention it and perhaps tag it with a 10% or 20% chance of development. That's basically because I know it wont develop over land and how great could the chances be of it developing in that final 24 hours of the present 5 day outlook?

Well Christine developed over Senegal in 1973 so it can happen

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or STORM2K. For official information, please refer to products from the National Hurricane Center and National Weather Service

[Siker]

Siker, I fully agree with your point but then if I were writing the TWO and realized that (as an example) a tropical wave would take "4 days" to reach the coast, that there'd be little reason for me to more than mention it and perhaps tag it with a 10% or 20% chance of development. That's basically because I know it wont develop over land and how great could the chances be of it developing in that final 24 hours of the present 5 day outlook?

It's really just about model output at that point weighted against climatology. For 25L, our three most reliable cyclogenesis models (Euro, UKMET, GFS) all show it developing within a 5 day period, but it's still only two days of available time over water.

I think we're on the same page.

[CrazyC83]

Siker, I fully agree with your point but then if I were writing the TWO and realized that (as an example) a tropical wave would take "4 days" to reach the coast, that there'd be little reason for me to more than mention it and perhaps tag it with a 10% or 20% chance of development. That's basically because I know it wont develop over land and how great could the chances be of it developing in that final 24 hours of the present 5 day outlook?

Well Christine developed over Senegal in 1973 so it can happen

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or STORM2K. For official information, please refer to products from the National Hurricane Center and National Weather Service

I believe reanalysis will find Christine didn't form at a TC right over land, but it did within hours of going over water as it was already a closed low.

[cycloneye]

More south emerging West Africa than in past runs.

[Hurricaneman]

I'm thinking this feature is going through the Cape Verde islands or just south in reality

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or STORM2K. For official information, please refer to products from the National Hurricane Center and National Weather Service

[cycloneye]

Over Cape Verde Islands.

[Hurricaneman]

This feature after 21W is going to go through 24-25C water around the Cape Verde Islands and that could temporarily slow down development until 30W and then I believe its off to the races

seems as though the 0ZGFS is showing this

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or STORM2K. For official information, please refer to products from the National Hurricane Center and National Weather Service

[cycloneye]

Moving away from CV Islands.

[cycloneye]

A little stronger than the 18z at this point.

[WeatherEmperor]

One thing to watch is 99L. If it lingers near Florida like the 18z Gfs showed, this can cause a weakness in the western atlantic ridge which is what turned it north. The 12z Gfs quickly kicked 99L out to sea which kept the ridge strong enough to send this wave all the way to Florida in the long range.


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[cycloneye]

120 hours.

[cycloneye]

Continues west and more stronger.

[RL3AO]

Stronger and faster so far than the 18z run. Ridge really builds quickly as Gaston passes by to the west and over the top.

[cycloneye]

Stronger and west at 150 hours.

[RL3AO]

This one is probably heading for FL again. So far it seems the faster runs are getting further west. Will be something to watch since the models often overestimate the forward speed of these systems in the eastern Atlantic.