Global model runs discussion

[cycloneye]

When you see this thread drop down the page without replies for days,it means that the models are not showing anything of significance for the time being.

Even the GFS that had for days a strong wave with a low attached dosent have it now.It only has waves tracking thru the Atlantic but nothing more.I suspect that as the weeks pass and August arrives,the models will start to show things that may have a chance to develop.

[Ed Mahmoud]

Healthy wave on Euro arrives vicinity Puerto Rico, dies either from unfavorable Caribbean conditions of crossing Hispaniola, hard to tell.

[wxman57]

One web page that we're taking notice of lately is the CIMSS MIMIC TPW site. We went to their ftp site at the bottom of the loop and saved all the images from 2007 and 2008, as well as those from June through the present for 2009. By watching a long loop of past storms that developed, we're seeing a pattern emerging. About 9 of the 16 named storms of 2008 formed from easterly waves moving off the coast of Africa. We went back and traced the origins of 2008 storms like Ike, Gustav, Fay, Hanna, and Dolly. In all cases of east Atlantic development, there was significant rotation in the TPW loops. And in just about all cases, it seems that the wave which resulted in a developing TC was preceded by another wave which cleared out the dry air in its path. Dolly was the exception, and it didn't develop until it reached the NW Caribbean.

What we've noticed over the past few days is that a very large high amplitude wave with plenty of TPW moved off the west coast of Africa, and it's being followed by another surge of TPW. This is very similar to what we saw prior to development in 2008. This is likely what the GFS has been seeing for the past week as something that might develop. One problem is that SSTs in the region remain a bit cool, and wind shear a bit high.

Main MIMIC TPW web site:
http://cimss.ssec.wisc.edu/tropic/real- ... /main.html

Note that the above web site appears to be having server issues this morning. Sometimes it times out or you can't connect.

[hurricanetrack]

That is fascinating and a very good idea- to save those images and do that analysis. Time lapse, whether it be clouds, plants, people or satellite photos, can show patterns in nature. We use it a lot in our work of studying hurricanes at landfall. I think wxman57's idea of using the loop to detect patterns in development is spot on. There has to be some rhyme and reason to it all. Will be interesting to see how things play out in the coming weeks. Perhaps in a little over a month, we will see the real season begin to take shape.

[Derek Ortt]

One web page that we're taking notice of lately is the CIMSS MIMIC TPW site. We went to their ftp site at the bottom of the loop and saved all the images from 2007 and 2008, as well as those from June through the present for 2009. By watching a long loop of past storms that developed, we're seeing a pattern emerging. About 9 of the 16 named storms of 2008 formed from easterly waves moving off the coast of Africa. We went back and traced the origins of 2008 storms like Ike, Gustav, Fay, Hanna, and Dolly. In all cases of east Atlantic development, there was significant rotation in the TPW loops. And in just about all cases, it seems that the wave which resulted in a developing TC was preceded by another wave which cleared out the dry air in its path. Dolly was the exception, and it didn't develop until it reached the NW Caribbean.

What we've noticed over the past few days is that a very large high amplitude wave with plenty of TPW moved off the west coast of Africa, and it's being followed by another surge of TPW. This is very similar to what we saw prior to development in 2008. This is likely what the GFS has been seeing for the past week as something that might develop. One problem is that SSTs in the region remain a bit cool, and wind shear a bit high.

Main MIMIC TPW web site:
http://cimss.ssec.wisc.edu/tropic/real- ... /main.html

Note that the above web site appears to be having server issues this morning. Sometimes it times out or you can't connect.

I've heard that the wave behind can block the SAL for the leading wave. That is something that has been discussed at HRD for a while

Of course, if the dry air ahead is not a SAL surge... the leading wave would clear the way for the trailing way

[HURAKAN]

Interesting.

[Sanibel]

Hurakan: Edit: I can't find anything on African loop that your model would have picked up. If you notice it busts out to 1015 pressure at the end of the run. The model probably doesn't pick up the dry character of the wave. Let's see.

[cycloneye]

The 00z GFS is more agressive (Again) as it brings a low pressure attached to a wave.The track is to the NE of the Leewards but not too far away from those islands.Lets see if other models join the GFS in this scenario as the timeframe is much less than when this model haved showed this in the past week.

114 hours

http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_114l.gif

126 hours

http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_126l.gif

150 hours

http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_150l.gif

168 hours

http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_168l.gif

204 hours

http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_204l.gif

00z GFS loop until 204 hours.

http://www.nco.ncep.noaa.gov/pmb/nwprod ... loop.shtml

Ok,I leave it there as the time goes ahead,the less credible the run is.

[gatorcane]

Closest approach to the islands is at 168 hours, according to 12Z GFS. I just checked the 06Z and it is not as bullish but still shows a strong amplified wave traversing the MDR...

[wxman57]

Here's what I see:

Pluses:
Shear is low in the region
Some slight rotation in mid levels visible on MIMIC TPW loop:
http://cimss.ssec.wisc.edu/tropic/real- ... /main.html

Minuses:
SSTs in the area marginal
Dry air intruding ahead of wave
Convection disorganized/scattered
Wind shear forecast to increase over the disturbance west of 50W

Based on its current appearance/characteristics and projections of increased shear along its path, I'd say that development chances are on the low side. It's said that about 10-15% of easterly waves develop each season, but the probability of such development isn't a steady 10-15%. Early waves have virtually no chance, and waves moving offshore in peak season have a significantly greater than 10-15% chance of developing. For this wave, its chances are likely less than 10-15%, probably in the neighborhood of 5% or so, just based on statistics. If it had a good core of convection then its chances would be greater.

[gatorcane]

Wxman, I tried opening that link but it is asking for a password.

[Sanibel]

If it's talking about that moderately convected wave around 30-35W it has the timing off because it says it won't cross 35W until wednesday. Good wave. A sign of things around the CV corner most likely...

[wxman57]

Wxman, I tried opening that link but it is asking for a password.

That's because I had the wrong link on my clipboard when I pasted it in. Try reloading this page and/or use this link:

http://cimss.ssec.wisc.edu/tropic/real- ... /main.html

[Ed Mahmoud]

Wxman, I tried opening that link but it is asking for a password.

That's because I had the wrong link on my clipboard when I pasted it in. Try reloading this page and/or use this link:

http://cimss.ssec.wisc.edu/tropic/real- ... /main.html

It could change, shear doesn't look bad right near Africa, but it doesn't look friendly in the MDR

[wxman57]

If it's talking about that moderately convected wave around 30-35W it has the timing off because it says it won't cross 35W until wednesday. Good wave. A sign of things around the CV corner most likely...

The GFS identifies 2 vort maxima (850mb) between 32-36W this morning. One is already west of 35W, the 2nd is predicted by the GFS to move past 35W tomorrow morning. We're monitoring a weak mid-level rotation near 7.9N/33.2W. This feature has been moving westward at 18-20 kts for the past 24 hours. Since it has only about 110nm to go to reach 35W, it'll pass that longitude in about 6 hours or so (this afternoon).

But there's quite a bit of subsidence in its path, and that subsidence is increasing. Development chances are very low, but not nonexistent. It could qualify for an invest if it was to develop some solid convection near the mid level rotation.

[gatorcane]

Wxman, I tried opening that link but it is asking for a password.

That's because I had the wrong link on my clipboard when I pasted it in. Try reloading this page and/or use this link:

http://cimss.ssec.wisc.edu/tropic/real- ... /main.html

That's a great link thank you. I have bookmarked it.

I see that area at 7.9/33.2. Actually it looks rather interesting and am surprised no members have pointed it out yet. Looks to be some kind of rotation and it is pulling away from the ITCZ maybe?

Members can see this area on the VIS loop here (bottom right corner):
http://www.ssd.noaa.gov/goes/east/tatl/loop-vis.html

Image:

[wxman57]

I see that area at 7.9/33.2. Actually it looks rather interesting and am surprised no members have pointed it out yet. Looks to be some kind of rotation and it is pulling away from the ITCZ maybe?

I think everyone else fell asleep out there. I'd say it may be worthy of a "Low" chance of development in the Atlantic TDO, but nowhere near 30%, as I said. A little bit of convection and it will be invest-worthy. Deepening trof along the east U.S. Coast would indicate recurvature east of the U.S. if anything were to spin up.

[gatorcane]

I started a new thread on this area.

I could see a code yellow soon if convection sustains or increases.

[cycloneye]

Its a billon lights ahead,but already the long range GFS falls into August and coincidence or not,it shows a big wave with a L on the 1rst.

http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_384l.gif

[gatorcane]

GFS trending towards consolidating an area of convection east of the Bahamas in about 1 week from now. This appears to be initiated by the wave that recently moved off Africa which traverses the Atlantic in a general W or WNW motion for the next week.

Here is the 12Z run 180 hours from now: