The MJO come July ....increased activity??

[cycloneye]

The MJO is a tricky beast in the Atlantic... works much better in the western and eastern Pacific. One question... where did you get that forecast map Aric Dunn? I have seen them before but can't remember where to find it again.

The models are showing some signs that the shear in the tropical Atlantic will reduce itself pretty significantly in a week or so. Check out:
http://www.cpc.ncep.noaa.gov/products/p ... hear_2.gif" target="_blank" target="_blank" target="_blank" target="_blank

I think the GF S is overdoing it.. but it shows a large are of low shear in the Atlantic. It takes more than shear this time of year... the stability is a big problem but that occasionally can be overcome. I think it will be more like mid July rather than early July cuz the GFS seems to move the MJO too fast (especially considering how slowly evolving the pattern is now).

I guess to summarize... I think we will have a chance at something in the low latitudes in July.. a la Dennis/Emily 05, Chantal 03, Bertha 96... (not necessarily very strong but something in July is pretty significant)... but it is hard to know. Maybe two weeks after the first WPAC storm forms roughly?

Benny,make it the third WPAC storm,not the first in 2007 and both that haved formed so far have been typhoons.

[benny]

ah... first storm.. I meant of the Atlantic hurricane season (Jun 1)... for the western Pacific... that makes sense right? My atlantic-o central point of view... in any event, I meant the first one since 1 June... it is pretty rare I think for the WPAC to have nothing in June... someone had a list a while back but I can't recall who. I took a brief look at the best track and see that nothing formed in June of 1996 or 1998 (looking at June since 1995).

[cycloneye]

ah... first storm.. I meant of the Atlantic hurricane season (Jun 1)... for the western Pacific... that makes sense right? My atlantic-o central point of view... in any event, I meant the first one since 1 June... it is pretty rare I think for the WPAC to have nothing in June... someone had a list a while back but I can't recall who.

Ok my friend,no problem.

[windstorm99]

If the GFS is correct wind shear should decrease drastically in the next two weeks,and since the jet stream flow is forecast to be flattening out in two weeks,upper level winds should remain quite favorable for tropical cyclone development through the end of the month.Adrian

Here is a graphic on the MJO....Look at all the blue areas covering most areas in the atlantic starting from about the 10th to the end of month.

Blue means means upward motion which greatly needed for tropical cyclone development.

['CaneFreak]

Hey Look!! The favorable MJO passed right by the Atlantic!! LOL It was here for a minute and then said, "C ya"!!!

http://www.cpc.ncep.noaa.gov/products/p ... thly.shtml

Do the loop and you will see what I am talking about...

[TheRingo]

This still shows the MJO phase is still in the Pacific and stalled there.

http://www.bom.gov.au/bmrc/clfor/cfstaf ... 90days.gif

[AnnularCane]

Wha...? I didn't know this thing stalled. I always assumed it kept moving.

[TheRingo]

Wha...? I didn't know this thing stalled. I always assumed it kept moving.

It looks like it's stalled there but maybe it's crossing over across the antarctic pole instead.

[benny]

It is very difficult to extract a MJO signal right now because there are many different types of tropical waves interacting. The bottom line is that globally.. most of the convection is still centered in the eastern hemisphere with the typical MJO response of enhanced upper highs due to convection over the western Pacific. Hence... the tropical cyclones that have been forming. Assuming a continued slow eastward propagation rate... the best upper conditions for genesis would be over the eastern Pacific in maybe 7-10 days or so.. then over the Atlantic a week or so after that. However... the MJO might not do much. It is just tough with SSTs only a little above average in the tropical Atlantic. Hard to know though.

Pretty long break without TCs in the eastern Pacific... had a similiar one last year though. it would be extremely rare to not having any storms form by 15 July...a break in formation of 50 days plus!

[TheRingo]

see it didn't skip us. It's about to cross over.

[MGC]

Per the CPC, the MJO is moving very slowly and the CPC expects the dry phase to remain in place across much of the Atlantic basin for the first half of July. This outlook appears to be verifying with all the dry air in the Atlantic. So, if anything does form it will likely be in the GOM, EC or WCarb IMO....MGC

[skysummit]

Well, if they say it's moving slowly and will be dry for much of the first half of July, does that mean it'll continue to move slowly when the wet phase is over us for the peak of the season? Hmmmm

[canetracker]

The MJO continues to progress nicely. Of course this latest available graphic is from 7/9 and I am sure it has progressed more since this graphic.


Any thoughts on how this may effect our chances of development in the next few weeks?

[windstorm99]

The MJO continues to progress nicely. Of course this latest available graphic is from 7/9 and I am sure it has progressed more since this graphic.


Any thoughts on how this may effect our chances of development in the next few weeks?

I think as we get the favorable part of the MJO now moving into the atlantic basin we should begin to see some activity in the next couple of weeks.Iam thinking from mid july to the begining of august.Adrian

[wxman57]

The MJO is just reaching the date line (180 deg) now. Latest projections bring it to the eastern Pacific toward the end of July. Studies have shown that there tends to be a significant increase in TC activity in the Gulf and Caribbean about 15 days after the MJO reaches the eastern Pacific. That points to the 2nd-3rd week of August. Here's the new graphic. Note no upward motion through July (left panel) for new forecast, old forecast is on right:

http://www.icess.ucsb.edu/asr/MJO_current_run.htm

[LarryWx]

It is my belief that these maps with greens and browns are overrated as far as their ability to determine peaks and lulls in the Atlantic season. I'm basing this strictly on my experience of following these charts for several years. During the heart of the active part of the season, I disinctly recall times when there was an active period when the browns dominated the Atlantic as well as inactive periods when there were greens. Whereas there may very well be some correlation, I really don't think there is a strong enough correlation to allow it to be a powerful predictor, especially when used alone.

[skysummit]

I don't believe anyone is using these MJO maps "alone". Simply enough, when we're in the wet phase, there's more convection. More convection = more of a chance of tropical development.

[canetracker]

Wxman57: Can you please explain to me why the Filtered OLR is the model you choose to use for the MJO? I have used all but found the Velocity Potential anomolies a bit easier to track. BTW, thanks for your posts as I always find them imformative.

Filtered OLR:



Velocity Potential


In regard to Larrywx:

It is my belief that these maps with greens and browns are overrated as far as their ability to determine peaks and lulls in the Atlantic season. I'm basing this strictly on my experience of following these charts for several years. During the heart of the active part of the season, I disinctly recall times when there was an active period when the browns dominated the Atlantic as well as inactive periods when there were greens. Whereas there may very well be some correlation, I really don't think there is a strong enough correlation to allow it to be a powerful predictor, especially when used alone.

I do agree with skysummit in that I don't believe anyone is using the MJO maps alone either. Most know their are many factors to consider, but if you have any reasoning to add to why your believe the velocity potential is over rated, I would like to hear your opinion as well.

[benny]

It is my belief that these maps with greens and browns are overrated as far as their ability to determine peaks and lulls in the Atlantic season. I'm basing this strictly on my experience of following these charts for several years. During the heart of the active part of the season, I disinctly recall times when there was an active period when the browns dominated the Atlantic as well as inactive periods when there were greens. Whereas there may very well be some correlation, I really don't think there is a strong enough correlation to allow it to be a powerful predictor, especially when used alone.

I concur. It works much better in the eastern Pacific than the Atlantic. I think it is important earlier and later in the season when the Atlantic takes a bit of a large-scale kick to get things going.

The greens are misleading on the 11 July graphic. There is a Kelvin wave (faster moving MJO-like wave, having much of the same atmospheric response on a smaller scale) moving through the region which should temporarily enhance things. The best signal for the MJO is actually in the central pacific... but really it is hard to determine. Another Kelvin wave should move through the eastern Pacific in 5-7 days and enhance things... and maybe by that point things in the Atlantic might be more favorable to allow the Kelvin wave to work some magic in the 10 day timeframe. That's really tough to know as interacts with the tropical waves are critical and unforecastable at this lead time. The MJO is really slow... like 60 days period... look at :

http://www.bom.gov.au/bmrc/clfor/cfstaf ... 0days.html

It has taken 40 days to get most of the way around the globe... simple extrapolation puts it in the Atlantic in the last week of the month...

[cycloneye]

I dont know if the development of the two Tropical Depressions and possibly named storms in the EPAC has to do with the wet phase of the MJO,but it's a coinsidence that the EPAC has been in the wet phase of MJO for more than 2 weeks and these two systems formed into TD'S.