1144 replies to this topic

[Mike.Ventrice]

Hi all,

I'm overly gushy about this wave and chances for genesis during the upcoming week. The IR image below shows the nice interaction with the wave and the diurnal cycle of convection over and downstream of the Guinea Highlands Region.




We might expect convection to fire up over the coast between 15-18Z and propagate northward down the lee of the Guinea Highlands as the wave moves out over the Atlantic later tonight.


We are also observing the passage of the strong eastward propagating convectively-coupled Kelvin wave over the Atlantic. Note that the entire Atlantic ITCZ is active today.






I want to illustrate how strong this Kelvin wave is (for it is also coupled with the convectively active phase of the MJO): This wave has swapped the total Positive VP200 signature that has been over the Atlantic since roughly June (there has been one other weaker Kelvin wave that swapped it to negative briefly) to a large area of negative VP200 values.





Given the relative state of the tropics, and in agreement with the ECMWF/GFS pouch products (GFS forecast below) I'm all in for this wave.

**EDIT** Sorry all- I forgot I am not allowed to post those results. I meant to use the GFS!

[Mike.Ventrice]

To illstrate the diurnal cycle of convection at the coast of West Africa during boreal summer, here's Figure 3 from my first 2012 paper:






Ventrice, M. J., C. D. Thorncroft, and M. A. Janiga, 2012a: Atlantic tropical cyclogenesis: A three-way interaction between an African easterly wave, diurnally varying convection, and a convectively-coupled atmospheric Kelvin wave. Mon. Wea. Rev., 140, 1108-1124.

[am19psu]

Yep. The signals have been strong for quite a few days now that this will be the first major of the season. Of note, the longer range Euro ensemble members are recurving this thing quite a bit farther west than the ops would imply.

[Mike.Ventrice]

I edited the post- sorry totally forgot I cant post ec-products. My apologizes

[HurricaneJosh]

Yep. The signals have been strong for quite a few days now that this will be the first major of the season. Of note, the longer range Euro ensemble members are recurving this thing quite a bit farther west than the ops would imply.

How far W?

[canderson]

I'm in Bermuda this Sunday to next Sunday via cruise. Put money on this forming and screwing me over.

[HurricaneJosh]

Why do people schedule cruises in hurricane zones during the climatological peak of the season? It never ceases to puzzle me.

[canderson]

Why do people schedule cruises in hurricane zones during the climatological peak of the season? It never ceases to puzzle me.

Because we gamble and purchase travel insurance so we don't care. I'd not do anything out of Florida this time if year but a NY to Bermuda run is a safer bet.

[HurricaneJosh]

Because we gamble and purchase travel insurance so we don't care. I'd not do anything out of Florida this time if year but a NY to Bermuda run is a safer bet.

If you don't care then I guess you're not worried about it.

I still don't understand why the cruise companies schedule that-- or why anyone would insure that sort of trip.

NY to Bermuda is just as likely to get hit as FL. Systems up there won't be as strong, but plenty disruptive with regard to a cruise. Take your cruises in the winter.

[Superstorm93]

I've been watching this for days now as well. ECMWF EPS Control suggests a pattern that could provide this with a more westerly component that the GFS suggests.

Bill 2009 redux?

[mapgirl]

Why do people schedule cruises in hurricane zones during the climatological peak of the season? It never ceases to puzzle me.

Same reason why people plan December weddings or child births.... We don't think ahead

[canderson]

If you don't care then I guess you're not worried about it.

I still don't understand why the cruise companies schedule that-- or why anyone would insure that sort of trip.

NY to Bermuda is just as likely to get hit as FL. Systems up there won't be as strong, but plenty disruptive with regard to a cruise. Take your cruises in the winter.

Wish I could! But it only goes May to August and work won't allow us to travel up except August to November. This is their last season sailing to Bermuda, to boot.

That said this guy will take a while to move so it wouldn't get near Bermuda until a week out probably right? Don't these take 6-7 days to travel that far?

[HurricaneJosh]

Same reason why people plan December weddings or child births.... We don't think ahead

My sister got married in December. It was quite beautiful, actually. She's not an icep*ss or anything, it just happen that way.

Back on topic... A Bill scenario would be a bit annoying. What are the chances that this makes it across into the W Caribbean and/or Gulf?

[HurricaneJosh]

Wish I could! But it only goes May to August and work won't allow us to travel up except August to November. This is their last season sailing to Bermuda, to boot.

That said this guy will take a while to move so it wouldn't get near Bermuda until a week out probably right? Don't these take 6-7 days to travel that far?

Depends how fast it's moving, but usually around a week, give or take. Laws of probability say you'll be fine. If not, you'll experience some interesting weather. So it's win-win.

[CoastalWx]

Euro is pretty strong with this potential TC as well. Tries to suck it north, but ridging then builds and brings it back on a NW track by d10. At this stage it's several hundred of miles NNE of the Antilles.

[Riptide]

I've been watching this for days now as well. ECMWF EPS Control suggests a pattern that could provide this with a more westerly component that the GFS suggests.

Bill 2009 redux?

From what I can tell, looking at the long-range pattern and the GFS/ECM ensembles. Timing is important and this is a situation where only an absolute recurve(Fabian, Bill) or west-tracking event (Ike, Andrew, etc) can occur. Once we approach September, teleconnections suggest that the persistent low pressure regime that has existed along the East Coast during August will move out and be replaced by a semi-permanent ridge as a result of changes in the AO and NAO.

The key here is the rate of development and forward speed, if the system fails to capture the persistent weakness at 60W; it may not get another chance to escape until reaching the conus.

[Superstorm93]

18z GFS 500mb pattern looks somewhat interesting. Trof over the East sticks around much too long to allow a ridge to build in, but that's over 9 days away.

I'm not sold on an insta-fish solution just yet, especially if this stays weaker than the globals suggest.

Sure enough, developing system after our African wave will find itself much farther west.

CMC...think different!

[Superstorm93]

94L



AL, 94, 2012081700, , BEST, 0, 110N, 172W, 20, 1010, DB

  *   ATLANTIC SHIPS INTENSITY FORECAST	   *
				    * GOES PROXY USED,	  OHC AVAILABLE	   *
				    *	  INVEST  AL942012  08/17/12  00 UTC   *
TIME (HR)		  0	 6    12    18    24    36    48    60    72    84    96   108   120
V (KT) NO LAND    20    22    25    30    35    45    55    65    75    85    92    99   104
V (KT) LAND	   20    22    25    30    35    45    55    65    75    85    92    99   104
V (KT) LGE mod    20    21    21    23    24    28    33    40    50    63    75    86    94

[thewxmann]

The future track of 94L seems to hinge strongly upon a TUTT that is forecasted to develop over the central ATL, which leaves behind a weakness. For at least the next five days though, a mid-lvl ridge should be able to steer 94L on a westerly or even slightly WSW trajectory. But since models can't really forecast TUTT's and ULL's that well, it's hard to gauge what happens after that. Probably will be difficult until Gordon exits stage right.

[thewxmann]

New ECM is much further south and west, BTW... seems similar to 0Z GFS through hr 168.

[Superstorm93]

ECM is much weaker through the first five days. Good for all who want a western track, but bad for those with no patience...

Sent from Tapatalk

[Floydbuster]

This appears to be major Hurricane Helene in the making.

[yoda]

This appears to be major Hurricane Helene in the making.

Because you think so?

[Floydbuster]

Because you think so?

No because it's the strongest tropical wave to exit Africa all season in the middle of August and the early model data indicates a major hurricane within 120 hrs and the next name is Helene.

[yoda]

No because it's the strongest tropical wave to exit Africa all season in the middle of August and the early model data indicates a major hurricane within 120 hrs and the next name is Helene.

I see SHIPS does, but I dont know that you can base pressure on system strength if you use globals... also considering EC is quite weak with 94L for a while

[Floydbuster]

I see SHIPS does, but I dont know that you can base pressure on system strength if you use globals... also considering EC is quite weak with 94L for a while

There are always these discrepancies with globals early on.

[yoda]

There are always these discrepancies with globals early on.

Well no duh, but stating MH in 5 days when the globals are all over the place is kinda silly

[Scott747]

Yep. The signals have been strong for quite a few days now that this will be the first major of the season. Of note, the longer range Euro ensemble members are recurving this thing quite a bit farther west than the ops would imply.

Well no duh, but stating MH in 5 days when the globals are all over the place is kinda silly

Just sometimes the need to bash or question Naso isn't always the best route to take. It has already been stated in this thread about this being potentially the first MH of the season.

[BIrving]

If you don't care then I guess you're not worried about it.

I still don't understand why the cruise companies schedule that-- or why anyone would insure that sort of trip.

NY to Bermuda is just as likely to get hit as FL. Systems up there won't be as strong, but plenty disruptive with regard to a cruise. Take your cruises in the winter.

It's apples and oranges you are comparing.

[BIrving]

0z Euro (appears to, from my very rough first view) bends what becomes a hurricane, back wnw just NE of PR. I'd pay to see that.

[HurricaneJosh]

It's apples and oranges you are comparing.

[BIrving]

Have you booked cruises in the past?

[am19psu]

Oh boy. I can tell this thread is going to need heavy moderation over the next week.

[CoastalWx]

Oh boy. I can tell this thread is going to need heavy moderation over the next week.

Have fun.

[mapgirl]

Oh boy. I can tell this thread is going to need heavy moderation over the next week.

As long as you continue to email me forecasts, I won't cause trouble