Dr. Jeff Masters' WunderBlog

Quoting Thundercloud01221991:


although 1000 of them is out of reach ... the 543 is getting close...we are at 434 confirmed tornadoes so far

434 confirmed? do you have a link?

Quoting Levi32:


No. Our first tropical wave usually comes off in late April or early May.

As of the past 6 years of tracking the first wave off of Africa, they have all occurred in Early May to Mid/Late May.
2004: May 21
2005: May 2
2006: May 11
2007: May 21
2008: May 2
2009: May 13
2010: May 2
2011: unknown

So as of what you can see here the first active year has a later Wave date than the 2nd active year from the active seasons of(2004 to 2005; 2007 to 2008) What i think has happend from recording and observing the activities of the 2 active years that come back to back when they occur, is that the 1st active season is like the primer(it has less storms, and less or the same amount of US landfalls. The 2nd year tend to have many more storms and hurricanes, but i believe 2010 has reversed the pattern and 2011 will be more active US activity wise, like it should be in the 2nd active year, but the 2011 season will be less active. in addition, from how its going right now, I'm going to go ahead and throw this out there, if my pattern observation is true, 2011's first wave will come off of Africa May 21 or 2, depending on how this pattern plays out. If the 1st wave comes off on the 2nd, I would be concerned that 2011 could continue the pattern and pull out to be the 2nd most active hurricane season on record... or 1st... no tellin...

Remains of Invest 91L... not to worry

Quoting TampaSpin:



I don't think many developing systems roll off Africa that has much meaning! Most development of anything meaningful is local bread stuff near the GOM or SW Caribbean. Am i wrong?

The assertion was: It is time to start looking for tropical waves off Africa in a few weeks.

Development is another issue.

Link
700hpa relative vorticity

Quoting Patrap:
If something spins up soon in the BOC and drifts Nne ,,lotsa phunny tings could get interesting.

real phunny tings yep

Quoting HurricaneDean07:
As of the past 6 years of tracking the first wave off of Africa, they have all occurred in Early May to Mid/Late May.
2004: May 21
2005: May 2
2006: May 11
2007: May 21
2008: May 2
2009: May 13
2010: May 2
2011: unknown

So as of what you can see here the first active year has a later Wave date than the 2nd active year from the active seasons of(2004 to 2005; 2007 to 2008) What i think has happend from recording and observing the activities of the 2 active years that come back to back when they occur, is that the 1st active season is like the primer(it has less storms, and less or the same amount of US landfalls. The 2nd year tend to have many more storms and hurricanes, but i believe 2010 has reversed the pattern and 2011 will be more active US activity wise, like it should be in the 2nd active year, but the 2011 season will be less active. in addition, from how its going right now, I'm going to go ahead and throw this out there, if my pattern observation is true, 2011's first wave will come off of Africa May 21 or 2, depending on how this pattern plays out. If the 1st wave comes off on the 2nd, I would be concerned that 2011 could continue the pattern and pull out to be the 2nd most active hurricane season on record... or 1st... no tellin...

Yeah that's my bad. I had that wrong in my head for some reason.

That list you posted from Weather456 is the only written record I can even find of tropical wave dates. One would think it would be useful to keep a record or a seasonal count of them for climatology purposes.

Quoting TampaSpin:



I don't think many developing systems roll off Africa that has much meaning! Most development of anything meaningful is local bread stuff near the GOM or SW Caribbean. Am i wrong?

I think that is a given, but he said nothing about development. He said we should be watching for our first tropical wave, which does not imply development.

Quoting HurricaneDean07:
As of the past 6 years of tracking the first wave off of Africa, they have all occurred in Early May to Mid/Late May.
2004: May 21
2005: May 2
2006: May 11
2007: May 21
2008: May 2
2009: May 13
2010: May 2
2011: unknown

So as of what you can see here the first active year has a later Wave date than the 2nd active year from the active seasons of(2004 to 2005; 2007 to 2008) What i think has happend from recording and observing the activities of the 2 active years that come back to back when they occur, is that the 1st active season is like the primer(it has less storms, and less or the same amount of US landfalls. The 2nd year tend to have many more storms and hurricanes, but i believe 2010 has reversed the pattern and 2011 will be more active US activity wise, like it should be in the 2nd active year, but the 2011 season will be less active. in addition, from how its going right now, I'm going to go ahead and throw this out there, if my pattern observation is true, 2011's first wave will come off of Africa May 21 or 2, depending on how this pattern plays out. If the 1st wave comes off on the 2nd, I would be concerned that 2011 could continue the pattern and pull out to be the 2nd most active hurricane season on record... or 1st... no tellin...

Just asking a question? But, the above dates are waves that came off Africa and developed into something. Otherwise i could find a Wave coming off Africa today and say that is the first wave. I don't mean to come across combative but, asking a question as to what a first wave off Africa really means and when one can say this is the first wave. Hope you understand what i saying and asking!

Quoting Levi32:


Yeah that's my bad. I had that wrong in my head for some reason.

That list you posted from Weather456 is the only written record I can even find of tropical wave dates. One would think it would be useful to keep a record or a seasonal count of them for climatology purposes.

I completely agree, that's why i have kept it up and running(filled out) since 2009. Going to keep track of it as much as I can... But seriously it's pretty interesting, how that "pattern" set up.

Quoting beell:
Post 328, 345,Levi and Pat...
Is there that much difference in the location of the loop between the initial velocity run and IR?

Ya'll looking at apples and oranges?

It's weird Beell, a lot of the navy's model runs look very different from the initial conditions sometimes.

Compare the NLOM initialization with the (I think more accurate) HYCOM initialization:

NLOM:



HYCOM:



And then Pat's image says HYCOM on it, but there's no way it moves the loop that far west in 120 hours. That's not realistic.

Quoting sunlinepr:

Getting Stronger, should see the first actual wave in the next week or two.

Guess my point is, Why couldn't this wave be considered the First Wave and what defines the first wave?

Ana April 20–April 24 Tropical Storm 60 994

Quoting beell:


The assertion was: It is time to start looking for tropical waves off Africa in a few weeks.

Development is another issue.

Tropical wave formation.



Easterly Waves
Long waves occur in bands of geostrophic wind flowing above the friction layer. Long waves may flow toward the west or toward the east depending on which of the major global wind belts they occur in. Easterly waves are "long waves" that occur within the trade wind belt, start over north western Africa, and propagate toward the west in the lower tropospheric tradewind flow across the Atlantic Ocean. They are first seen usually in April or May and continue until October or November. They occur between 5-15 degrees N. They have a wavelength of about 2000 to 2500 km, a period of ~3-4 days, and move at approximately 18 - 36 km/h. Approximately two easterly waves per week travel from Africa to North America during hurricane season. Passing from the African continent onto the cool Eastern Atlantic, the waves generally decay, but remnants mostly survive to the Western Atlantic and Caribbean where they regenerate. Only 9 out of 100 easterly waves survive to develop into gale-force tropical storms, or full-fledged hurricanes.

About 60% of the Atlantic tropical storms and minor hurricanes (Saffir-Simpson Scale categories 1 and 2) originate from easterly waves. However, nearly 85% of the intense (or major) hurricanes have their origins as easterly waves. The majority of synoptic scale systems from Africa propagate beyond the Caribbean and the Central American Isthmus into the Eastern Pacific, where some intensify into Tropical Storms. It has been suggested that nearly all of the tropical cyclones that occur in the Eastern Pacific Ocean can also be traced back to Africa. Many Typhoons in the Western Pacific are also believed to develop from Easterly Waves, although more work is needed on the relationship of Easterly Waves in the Western and Eastern Pacific.

Fig.1. Approximate location, amplitude and wavelength of easterly waves.

At first, an easterly wave has a small amplitude, and produces mild rain showers. Powerful thunderstorms and the force of high-altitude winds amplify the wave when atmospheric conditions are favourable. Several severe thunderstorms begin to form, and eventually a tropical storm may develop.

Fig. 2. The development of easterly waves off the west coast of Africa.

Quoting TampaSpin:


Just asking a question? But, the above dates are waves that came off Africa and developed into something. Otherwise i could find a Wave coming off Africa today and say that is the first wave. I don't mean to come across combative but, asking a question as to what a first wave off Africa really means and when one can say this is the first wave. Hope you understand what i saying and asking!

You won't find a wave today. A wave heralds the advance of the African Easterly Jet out into the eastern ATL and the slow northward march of the ITCZ. These disturbances are found near the 600-700mb level. You may find a surface feature today or tomorrow but you will not find a true easterly wave.

what would actually happen if the loop current broke off into a loop eddy?

Wave or not... it won't develop

Quoting TampaSpin:



Guess my point is, Why couldn't this wave be considered the First Wave and what defines the first wave?

The tropical waves, aren't just balls of convection, they have(when they're strong) Structure, T-storms attempting to Organize, Convection(of Coarse), and a good amount of vorticity.

Quoting TampaSpin:


Just asking a question? But, the above dates are waves that came off Africa and developed into something. Otherwise i could find a Wave coming off Africa today and say that is the first wave. I don't mean to come across combative but, asking a question as to what a first wave off Africa really means and when one can say this is the first wave. Hope you understand what i saying and asking!

I think you are misunderstanding. None of those above tropical waves developed into anything that I am aware of (maybe one got into the southwest Caribbean, but I don't know).

There is a very clear definition of a tropical wave, and we have had none so far. The blobs of convection that start coming off are not yet tropical waves. There is a reason why the NHC leaves the surface map blank.

Quoting beell:


You won't find a wave today. A wave heralds the advance of the African Easterly Jet out into the eastern ATL and the slow northward march of the ITCZ.

So, basically as the ITCZ climbs out of the Southern Hemisphere is when the first cluster of storms is considered a Wave.

Quoting HurricaneDean07:
The tropical waves, aren't just balls of convection, they have(when they're strong) Structure, T-storms attempting to Organize, Convection(of Coarse), and a good amount of vorticity.

not just that... they have to be in a shear/dry air free environment w/ warm waters

Quoting trHUrrIXC5MMX:
Wave or not... it won't develop

Who said it would develop, there's not any kind of wave to talk about anyway, and you don't look for CV development until Late July to Early October.

Quoting trHUrrIXC5MMX:


not just that... they have to be in a shear/dry air free environment w/ warm waters

I'm not talking about how they develop, im talking about what a tropical wave is.

Quoting TampaSpin:


So, basically as the ITCZ climbs out of the Southern Hemisphere is when the first cluster of storms is considered a Wave.

No. Tropical waves are not clusters of thunderstorms within the ITCZ. They are literally waves within the African Easterly Jet at about the 650mb level with defined potential vorticity maxima and zonal wind shifts.

In fact, quite a few tropical waves per season come off Africa and continue across the eastern Atlantic with little or no convection whatsoever.

Severe weather for Nortern Texas and Oklahoma Tuesday???

Sorry for my confusion as i really don't honestly track anything unless it is of meaning and possible for development. Sorry to be so dumb on this one. I actually did not realize tho that a Wave must be contained within the ITCZ to be considered a wave if i understand this correctly. Sorry all and thanks for clearing my mind!

Quoting trHUrrIXC5MMX:
Severe weather for Nortern Texas and Oklahoma Tuesday???

Yep

Quoting HurricaneDean07:
Who said it would develop, there's not any kind of wave to talk about anyway, and you don't look for CV development until Late July to Early October.

I said it will NOT develop.

Quoting TampaSpin:


So, basically as the ITCZ climbs out of the Southern Hemisphere is when the first cluster of storms is considered a Wave.

The AEJ and waves are a consequence of the temperature gradient between equatorial Africa and the much warmer Sahel/Saharan Desert. That gradient does not exist quite yet.

full northern hemisphere
enhanced infared red animation

Quoting TampaSpin:
Sorry for my confusion as i really don't honestly track anything unless it is of meaning and possible for development. Sorry to be so dumb on this one. I actually did not realize tho that a Wave must be contained within the ITCZ to be considered a wave if i understand this correctly. Sorry all and thanks for clearing my mind!

They can be embedded within the ITCZ but they aren't always. Often we wait for them to become independent from the ITCZ before giving them good chances to develop. I gave their basic definition in #380.

Quoting trHUrrIXC5MMX:


I said it will NOT develop.

I know, but know one was talking about formation of a tropical wave, Tampaspin is a bit confused about tropical waves, and were helping him out.

Quoting beell:


The AEJ and waves are a consequence of the temperature gradient between equatorial Africa and the much warmer Saheel/Saharan Desert.

Bell i understand the dynamics of what causes a spin and land heat effects. I was simply trying to understand what is considered the first wave and what the definition of the first wave is as i might have considered the ones coming off Africa now as Wave. I will shut up and just simply observe!

It should also be noted that if a tropical wave ultimately detaches from the ITCZ, it loses a large supply of moisture and instability and can struggle thereabouts, at least until it can manage to become self sufficient. This is why the incipient wave that spawned Danielle last August had so much darned trouble intensifying once it detached from the ITCZ.

Quoting Levi32:


They can be embedded within the ITCZ but they aren't always. Often we wait for them to become independent from the ITCZ before giving them good chances to develop. I gave their basic definition in #380.

Levi thanks i fully understand that already! Thank you!

Look at this weird thing (since waves are begining to roll off) chances are we might...



A wave eventually came Bertha.. am early Cape Verde type hurricane.

Chaces are we can get one like this soon if right conditions are present.

We had already 90L and 91L, chances for Arlene are increasing

Quoting KoritheMan:
It should also be noted that if a tropical wave ultimately detaches from the ITCZ, it loses a large supply of moisture and instability and can struggle thereabouts, at least until it can manage to become self sufficient. This is why the incipient wave that spawned Danielle last August had so much darned trouble intensifying once it detached from the ITCZ.

Honestly if a potential spins does not detach it is rarely classified as a storm until it makes its way out of the ITCZ! It must sustain its own dynamics and spin!

Quoting TampaSpin:


Bell in understand the dynamics of what causes a spin and land heat effects. I was simply trying to understand what is considered the first wave and what the definition of the first wave is as i might have considered the ones coming off Africa now as Wave. I will shut up and just simply observe!

It's cool, Tampa. I remember last year we were sitting around arguing against the NHC about the first tropical wave. Nope. "Not yet", we all said.

NHC refrenced a time/height series from Dakar on the coast of Africa in the next TWD and there it was. Big as Dixie! So even if you think you know what it is-it don't mean you can find it!

Back to simply surfing!

Quoting TampaSpin:


Levi thanks i fully understand that already! Thank you!

Tampa
Actually!
Thanks for the question and pursuing it.
The following give and take was very informative.
Spathy learning moment.

Quoting TampaSpin:


Honestly if a potential spins does not detach it is rarely classified as a storm until it makes its way out of the ITCZ! It must sustain its own dynamics and spin!

Tomas of 2010 knew how to intensify and deal with the ITCZ at some point without weakeing for a shot time

Quoting spathy:


Tampa
Actually!
Thanks for the question and pursuing it.
The following give and take was very informative.
Spathy learning moment.

its actually good to have these moments now during down times. I have learned all i know (which is still little) from this blog.

Anyway, the time height series charts are probably the easiest way to spot a wave as they leave the coast of Africa. These are not much more than a look up through the atmosphere over a given point.

A wave signature shows a sharp wind shift from NE to SE as the wave passes at 600-700mb. And there is usually an increase in moisture/RH as well.

Bookmark this one if you want.

Upper Air Time Section Analyses