Disturbed weather in Eastern Atlantic (Is invest 95L)

[hurricaneCW]

Now this is what I wanted to see. A true Cape Verde spinner that travels a long distance. The model support is increasing so I have to believe that we have a greater than normal chance of seeing the wave spin up into a storm. However, I still have my doubts that it will really happen given what I've seen so far this season, but we will see this upcoming week if we get a storm or not. If we do the formation date will be right near August 20th.

[Sanibel]

The east Atlantic ITCZ is maintaining convection like a line of fire in front of this emerging wave. Could be a good sign of favorability?

[cycloneye]

The east Atlantic ITCZ is maintaining convection like a line of fire in front of this emerging wave. Could be a good sign of favorability?

This is what you are talking about.

[KWT]

Now this is what I wanted to see. A true Cape Verde spinner that travels a long distance. The model support is increasing so I have to believe that we have a greater than normal chance of seeing the wave spin up into a storm. However, I still have my doubts that it will really happen given what I've seen so far this season, but we will see this upcoming week if we get a storm or not. If we do the formation date will be right near August 20th.

Yeah I've been pretty confident of this system developing for a while now and still see no reason to go against that idea. The only thing I will say is the models are trending towards a slower development at first, which probably raises the risk down the line for the NE Caribbean and the E.coast and Bermuda I'd assume as well if it recurves.

[OuterBanker]

I think if a study was done. The odds of getting the daily number right is about the same as the GFS 360 being right. It's the pattern that I am concerned about. It is the first time that all the models are seeing the ramp up. I know all the naysayers have written off the season. But most of us know that a La Nina season is traditionaly a late start. I am also concerned that we may have to extend the Aug 15 to Oct 15 hell weeks to the end of Oct or even early Nov.

[cycloneye]

Test Invest Introduced, PGI-30L

http://www.met.nps.edu/~mtmontgo/PGI30L.html

Main Site of Pounch invests.

http://www.met.nps.edu/~mtmontgo/storms2010.html

More info will be released very soon at the site but here is the initial position. Around 10N since yesterday so a westward motion continues.

[KWT]

Not much in the way of Vort. down there at the moment though.

Looks to me like the GFS merges the low thats quite far north and the wave further south, which is pg-30l.

Interestingly the models orginally made the Northern wave the dominant one but now they progged the more southerly wave to be stronger and take over.

[LarryWx]

With the crucial 8/15-21 period for Cape Verde storm** formation approaching, the concentration of U.S. hits (I'm not including P.R. in this post) that period has produced during moderate to strong La Nina's, and the numerous runs in a row that models have shown one forming, I feel it is important to emphasize the following:

Exact dates of FORMATION (TD+) of the 12 CV storms that later hit the U.S. during the 19 mod.+ La Nina seasons (like 2010) since 1871:

8/3, 8/7, 8/15, 8/15, 8/19, 8/20, 8/21, 8/28, 9/7, 9/10, 9/15, and 9/25. So, peak formation frequency was during 8/15-21.

The last several runs of the GFS/Euro have shown a CV type of TD forming ~8/18, which is smack dab in the middle of the 8/15-21 peak period of formation for eventual U.S. hitters. Is 2010 going to add a new entrant for around 8/18? We'll know by around 9/1 when we see where it eventually goes (assuming it actually develops, obviously).

There's obviously no way to accurately forecast a CV storm U.S. hit from a formation near this period. Moreover, the odds of a single storm eventually hitting the U.S. are low: only ~one in six ever hits the U.S. based on the period 1960-2009 (154 CV storms produced only 25 U.S. direct hits). So, to actually forecast a U.S. hit from any one storm would be going out on a limb. However, I do know three things:

1) The chance of at least one CV storm U.S. hit during moderate to strong La Nina seasons is near or higher than twice the chance for other seasons based on the 19 season stats.

2) The period 8/15-21 has easily had the highest concentration of U.S. hitting CV storms form of any seven day period during the 19 mod. to strong La Nina's (five vs. no more than two for any other seven day period).

3) Nine CV storms formed 8/15-21 during the 19 seasons. So, an impressive 5 of 9 (56%) hit the U.S., which is way higher than the normal one in six hits fwiw.

Therefore, although I'm certainly not forecasting it due to the low odds for all CV storms in all years, I'd at least be extra vigilant for a potential U.S. hit from what ends up forming in the CV area next week. Based on the above mentioned climo and the models now coming further west, I'd say that the odds are a fair amount higher than the normal one in six chance due to it both being both a mod. to strong Nina and it forming within 8/15-21....probably between one in two and one in three.

Where did those five storms hit?

- 1893: #4 NJ/NY

- 1893: #6 GA/SC border (after brushing FL)

- 1964: Cleo S FL

- 1988: Chris GA/SC border (after brushing FL)

- 1998: Bonnie NC

So, I'd also say that any potential U.S. hit from this potential formation would very likely be east coast rather than gulf coast and probably within the period 8/28-9/2.

***EDIT: any intial WSW movement once the TD forms increases the U.S. threat a lot further based on climo of non-El Nino seasons. For non-El Nino seasons, a whopping 70% (9 of 13) of E. Atlantic WSW movers on record either made landfall or grazed the U.S. since 1851!! So, let's see if the TD moves WSW during its early stages.


**My def. of Cape Verde storm: tropical storm/hurricane that first became at least a TD E of 50W and S of 20N

[cycloneye]

Many Features that you can see about Test Invest PGI-30L

[cycloneye]

Below is a synopsis for PGI-30L.

http://catalog.eol.ucar.edu/cgi-bin/pre ... opsis.html

Code: Select all

PREDICT pouch synopsis

--------------------------------------------------------------------------------
Date (UTC): 2010/08/14 14:48
Author: Boothe
Submitted at (UTC): 2010/08/14 14:51
Revised at(UTC): 2010/08/14 15:24
--------------------------------------------------------------------------------
Pouch Name: PGI30L        Official Name:        Initial Center Point: 9N   2E
Notes:

Tracks at end is a bit confusing ... may actually involve a jump
to another circulation.  (Like with PGI27's track, use the later
portion of PGI30L's track with caution.  Examine field loops for
more detail.)


--------------------------------------------------------------------------------
ECMWF:  Phase Speed: -8.9        Determination: v700 only        Level tracked: 700 hPa

Track definitely jumps west.
GFS:      Phase Speed: -9.8        Determination: v700 only        Level tracked: 700 hPa


Track: 120h
Relatively smooth track as it heads off of Africa, but then
slows.
UKMET:  Phase Speed: -8.5        Determination: v700 only        Level tracked: 700 hPa


UKMET has a relatively weak depiction of PGI30L, and it seems to
dissipate as it leaves the coast ... at which point, the track
makes a (unrealistic) jump to the west to another pouch.
NOGAPS:  Phase Speed: -7.7        Determination: v700 only        Level tracked: 700 hPa

Track: Low confidence 24-60 h ... jumps west?


[KG4HPN]

Very cool link, Luis. Thanks! Looking at the WV imagery, there's an interesting broad low pressure swirl right in the area that this pouch is progged to be in 96 hours. I wonder if that contributes to the uncertainty of the track further down the timeline?

[cycloneye]

Thank you Larry for those very interesting stats. In other words, lets get those charts ready shortly to start tracking those beasts that mother nature always has instored every year and hopefully landfalls are reduced to a minimal.

[weatherwindow]

just for grins...2010 old farmer's almanac "predicts" a possible hurricane for florida aug 31-sept 2...no link available as far as i can tell...rich

[cycloneye]

Run # 12 in a row by GFS

Here we go with another run, the 12z.

[cycloneye]

114 hours.

[cycloneye]

132 hours.

Look at those H aligned.

[KWT]

A much quicker development from the 12z GFS with no trouble from any vorticity regions unlike the 06z run.

Pretty far north on the 12z out to 132hrs, to get a hit from there would be quite impressive but you never know...

[cycloneye]

156 hours.

[cycloneye]

180 hours.

[KWT]

All aborad the recurve train on the 12z GFS from the looks of things.

Note the quicker development once again probably makes a world of difference with the probable track....and also the 12z GFS is WAY deeper with the E.Atlantic trough...

It is worth noting the 12z GFS usually has the strongest cold bias of all the GFS runs, so its probably rather overdoing the strength of the upper trough in the E.Atlantic.