Atlantic Tropical Action 2011 - Part IV

[Floydbuster]

14/3/2

1 U.S. landfall: Hurricane Irene (Cat 1 NC, NJ)

Incredible. No doubt more is in store, though.

[phil882]

The ECWMF is dead as a doornail out to 240 hours. I think Adam is right in suggesting we take an extended lull before activity picks back up by the end of the month. Conditions are just not favorable right now over a large chunck of the Atlantic basin.

[GaWx]

Folks,

The 12 Euro takes what appears to me to be Pouch P29L, now located SE of the CV's., westward and develops it into a TD near 10N, 28W at 72 hours (9/19 12Z) fwiw. Anyone else notice this? Let's see what the Euro does with it from there.

[atownwxwatcher]

Folks,

The 12 Euro takes what appears to me to be Pouch P29L, now located SE of the CV's., westward and develops it into a TD near 10N, 28W at 72 hours (9/19 12Z) fwiw. Anyone else notice this? Let's see what the Euro does with it from there.

Perhaps why as of 2 PM we now have a AOI (area of interest) at 10%

[GaWx]

The 12Z Euro then strengthens this CV wave and takes it to ~45W but then recurves it there on 9/23 as the ridge to its north weakens/splits.

[NorEaster27]

With the mean trough over the east coast in the long range, any threat would most likely recurve.

[HurricaneJosh]

Boring. The African cyclones just suck this year. I'm so glad we're getting into W-Caribbean season-- just completely sick of anything coming from the E Atlantic.

[GaWx]

Boring. The African cyclones just suck this year. I'm so glad we're getting into W-Caribbean season-- just completely sick of anything coming from the E Atlantic.

Josh,

I heard that the boredom of this season (outside of Irene) has put Sominex out of business.

[Ed Lizard]

Too bad about the resolution truncation on the GFS because the wave entering the Southern Caribbean looks interesting, if it tracked through into the Western Caribbean, but the lobotomized GFS seems to turn it Northward before it even really develops. The results, a storm headed for Florida over 2 weeks might not be all that different if it developed in the Western Caribbean.

As mentioned, the Euro is blah in this basin.

[phil882]

We are currently in a pretty unfavorable period for tropical cyclone formation across the Atlantic according to the latest 12z ECWMF. Looped below is the 200mb flow at 48 hours and 120 hours. First, you notice intially that there plenty of light and variable flow at 200mb across most of the basin. However, despite the absence of any strong westerly flow in the upper levels, the stronger low level easterlies are keeping most of the basin sheared. This is largely due to the fact that the subtropical jet (illustrated by the red line) is starting to sag to the south which often starts to occur by this point in the year. Thus, the Cape Verde season is drawing to a close as we start to see the 200mb ridge become displaced further south, and African waves are moving into this light and variable 200mb flow and can't remain vertically stacked as the low level easterlies continue to run out into the Atlantic basin leaving the upper level flow behind.

There is some hope though. The 12z ECWMF was pretty bullish in developing one more strong 200mb ridge in the long range by day 5. This is one of the reasons why its generates two tropical cyclones during this time frame off the Cape Verde Islands, as the conditions will be favorable. However, as we start to shift into Autumn, the subtropical jet and polar jet will continue to migrate southward, which will make recurring tropical 200mb ridges like the one witnessed below in the modeling increasingly rare over the Eastern Atlantic.

[MJO812]

Too bad this is hour 384 on the 0z GFS

[Srain]

Actually, there is a bit of merit to what the operational GFS in la la land is depicting. As we near the end of the month, there does appear to be a robust Kelvin wave that will increase lift across the Western Basin and the Euro ensembles suggest the 'Carla cradle' will be the area to watch has the monsoonal trough begins to lift N once again. We will see.

[Ed Lizard]

The operational Euro also shows a large, deep and somwhat positively tilted trough in the East, it'd be hard to get a Carla cradle storm even to South Florida unless the pattern changes.

I do see some reason for my usual glass half full optimism as we head to October for a pattern more favorable for a Pensacola Pounder or Tampa Trampla. The trough in the ensemble means is shifting East and won't scoot something from the Caribbean out through the G. Antilles and East of Florida if the ensembles have the right idea.

[Srain]

Well now would you look what the cat dragged in...

[blazess556]

BEGIN

NHC_ATCF

invest_al982011.invest

AL, 98, 2011091800, , BEST, 0, 104N, 352W,

There is now Invest 98L. Looks like this is what the models develops. Well, if you believe the 00z GFS, there should be Ophelia in the Eastern Atlantic in 3-4 days.

[phil882]

Just from the look of the 00z gfs, it looks like 98L could have very similar problems to what Maria just went through... stronger low level flow as the ridge intensifies against the weaker upper level flow.

[HurricaneJosh]

It's almost 20 September. Time to forget about African cyclones-- unless you're some pervert who gets off on sheared fish near the Azores.

[HurricaneJosh]

But for what it's worth, the BAMS take 98L essentially W over the next five days.

[phil882]

But for what it's worth, the BAMS take 98L essentially W over the next five days.

Don't hold your breath.

[HurricaneJosh]

Don't hold your breath.

See my previous post.

[Srain]

Lemonade now being served across the Atlantic. 97L, 98L, 99L and future 90L about to roll off the African Coast. The only one of mild interest appears to be 98L and may well be a threat to the Caribbean Islands. The Operational 00Z Euro is suggesting a weak disturbance in the Central Caribbean in the longer range and the Euro ensembles still like the Western/SW Caribbean (Carla cradle) as well. We will see.

[brad1551]

Lemonade now being served across the Atlantic. 97L, 98L, 99L and future 90L about to roll off the African Coast. The only one of mild interest appears to be 98L and may well be a threat to the Caribbean Islands. The Operational 00Z Euro is suggesting a weak disturbance in the Central Caribbean in the longer range and the Euro ensembles still like the Western/SW Caribbean (Carla cradle) as well. We will see.

[brad1551]

100% agree.

[GaWx]

Folks,

Because I'm anticipating that the fall/winter of 2011-12 will retrospectively (once all of the data has been compiled) be officially classified as a La Nina, I decided to do an analysis of CONUS H hits during +AMO La Nina's and compare this to non-La Nina +AMO seasons since 1877. I concentrated on the period 10/1-15.

Interesting stats:

1) MAJOR CONUS 10/1-15 H hit chance during +AMO MUCH higher if La Nina:

a) Whereas only 2% (only 1 of 57) of non-La Nina 10/1-15 periods had a major CONUS H hit, a respectable nearly 30% (8 of 27) of La Nina 10/1-15 periods had a major CONUS H hit! Another way to look at this: a whopping 8 of 11 +AMO seasons with a major 10/1-15 CONUS H hit were La Ninas. Moreover, 1 of these 8 seasons, 1893, had TWO major hits during 10/1-15!

b ) A whopping 77% of the La Nina H hits (10 of 13) were major hits during 10/1-15!

Aside: ZERO -AMO non-La Nina seasons had a 10/1-15 CONUS major H hit!

2) 10/1-15 CONUS H hits much more likely +AMO Nina vs. +AMO non-Nina:

Whereas only ~16% (9 of 57) of non-La Nina 10/1-15 periods had a CONUS hit, a very respectable ~39% (11 of 28) of La Nina 10/1-15 periods had a CONUS H hit. Moreover, 2 of these 8 seasons, 1893 and 1964, had TWO H hits during 10/1-15.

3) W. Caribbean origins +AMO Nina:

Whereas only 9% (1 of 11) of the 9/16-30 La Nina CONUS H hits were first declared a TC in the W. Caribbean, a whopping 69% (9 of 13) of the 10/1-15 La Nina CONUS H hits were first declared a TC in the W. Caribbean.

4) 10/1-15 specific H hit dates +AMO Nina:

Dates of the 13 CONUS H hits during La Ninas (majors bolded): 10/2, 10/2, 10/3, 10/4, 10/4, 10/5. 10/8, 10/11, 10/12, 10/13, 10/14, 10/15, and 10/15. This suggests that the two biggest threat periods per climo may be 10/2-5 and 10/11-15 although the sample sizes are fairly small after breaking up into these shorter intervals.

--------------------------------------------------------------------------------------------

So, these stats tell me that those who desire H action, especially major, in/near the CONUS this season will still have a halfway decent opportunity during 10/1-15 based on +AMO La Nina climo.

**This is the corrected version (done 9/19/11) to adjust for errors.**

[HurricaneJosh]

I notice most of the models seem to agree that 98L will move W into the E Caribbean. On the other hand, none of them develops it much; even the SHIPS has really backed off since yesterday. Blah.

Let's see something brew in the W Caribbean. That would be awesome. Time for the Africa show to end; it was just a big flop this year.

[atownwxwatcher]

As of 2 AM we now have a cherry!

[HurricaneJosh]

As of 2 AM we now have a cherry!

Noice. The GFS, GFDL, and HWRF all keep it W into the E Caribbean-- and I notice the SHIPS has gotten a little more enthusiastic this evening. Something to watch, I guess.

[phil882]

Noice. The GFS, GFDL, and HWRF all keep it W into the E Caribbean-- and I notice the SHIPS has gotten a little more enthusiastic this evening. Something to watch, I guess.

While in the short term 98L has a good chance for development, I think we are going to see a very similar setup to how Maria played out with 98L speeding up too quickly to allow the upper level flow to catch up as the ridge intensifies. It's a common problem for tropical cyclones in the deep Atlantic late in the season as the upper level ridge is suppressed southward compared to the low/mid level ridge which ends up producing weaker upper level flow compared to stronger low/mid level easterlies. In the end, both the GFS and ECWMF show this feature eventually shearing out as it approaches the Caribbean. We will see what transpires. A weak to moderate TS is certainly possible but probably nothing beyond that.

[wxmx]

Big Bermuda ridge will make it possible for 98L to get into the Caribbean, but like Phil, I'm bearish with this one... shear, troughs and probably Hispaniola await it there.

[icebreaker5221]

Despite the general discontent with this season, our ACE is up to 76 for the year, 9 above average year-to-date.