Atlantic Tropical Action 2013

[CoastalWx]

Good stuff over the last couple of pages. Beats the temp talk disaster in my subforum.

[Mike.Ventrice]

Find the period and comma keys.

[Mike.Ventrice]

At the risk of straying off-topic here, I remember a presentation from (yet another) Albany guy who did a lot of research with intensity increases in TCs after landfall:

 

http://www.atmos.albany.edu/student/mpotter/research.html

 

Research tied intensity increases with TC Danny to interactions with an upper-level midlatitude jet - diabatic heating impacts, negative PV advection, and frontogenesis in the divergent equatorward entrance region of the jet. Too bad his written thesis isn't online.

 

I'll see if I can get a version for you if you'd like, Matt use to be in my grad-office

[Ed Lizard]

 

Oh, hey, while you're here, anything in the wide wide world of the MJO or CCKW that suggest the 10 to 15% of GEFS members that develop Westbound moving TCs in a little over two weeks in the BoC (IIRC, there was a sub 984 mb member at 12Z yesterday) are actually on to something.  The odd thing, even many of the members not developing TCs have been lowering pressure in the BoC.  And concentrated in the BoC.

 

If there was anything going on, I'd defer asking this.

 

Yesterday's GEFS means where the mini-cluster of individual member storms was...

 

[bluewave]

At the risk of straying off-topic here, I remember a presentation from (yet another) Albany guy who did a lot of research with intensity increases in TCs after landfall:

 

http://www.atmos.albany.edu/student/mpotter/research.html

 

Research tied intensity increases with TC Danny to interactions with an upper-level midlatitude jet - diabatic heating impacts, negative PV advection, and frontogenesis in the divergent equatorward entrance region of the jet. Too bad his written thesis isn't online.

 

David was one of my favorite cases since it surprised local forecasters here in 1979.

 

http://journals.ametsoc.org/doi/pdf/10.1175/1520-0493%281995%29123%3C3268%3APTCRIA%3E2.0.CO%3B2

 

An analysis is conducted from a potential vorticity (PV) perspective of the reintensification of Tropical Storm David over the northeastern United States in September 1979. David, a major long-lived hurricane, originated near the Cape Verde Islands in late August 1979. It made final landfall in Georgia on 4 September 1979 and weakened rapidly thereafter. The noteworthy aspect of David was its subsequent reintensification approximately 27 h after landfall as a warm-core disturbance in a weakly baroclinic environment. In this regard the redevelopment of David is unlike the classical extratropical transformation of a tropical storm in a strongly baroclinic environment that has been documented in the literature. The authors' analysis of the evolution of the dynamical tropopause subsequent to storm landfall revealed that David reintensified in response to “tropopause lifting” (upward displacement of the dynamic tropopause) ahead of a nondeepening and otherwise very weak upper-tropospheric disturbance. The “tropospheric lifting,” associated with both advective and diabatic warming poleward and eastward of David, resulted in steepening of the tropopause and compaction of the PV maximum associated with the weak upper-tropospheric disturbance. As the compacted upper-level trough accelerated north-eastward, the associated ascent and low-level horizontal convergence were rendered especially efficient in generating cyclonic vorticity by the neutral stability (relative to the moist adiabat) of the moist tropical air mass surrounding David and the presence of the preexisting low-level vorticity maximum associated with the remnant tropical storm circulation.

[Mike.Ventrice]

Oh, hey, while you're here, anything in the wide wide world of the MJO or CCKW that suggest the 10 to 15% of GEFS members that develop Westbound moving TCs in a little over two weeks in the BoC (IIRC, there was a sub 984 mb member at 12Z yesterday) are actually on to something.  The odd thing, even many of the members not developing TCs have been lowering pressure in the BoC.  And concentrated in the BoC.

 

If there was anything going on, I'd defer asking this.

 

Yesterday's GEFS means where the mini-cluster of individual member storms was...

 

 

 

I have less confidence in this solution as the GFS continues to retrograde the MJO signal back over the Indian Ocean in 2 weeks where in reality it will likely be over the East Pacific (phase 7-8). There is a strong CCKW likely to pass the Atlantic next week, that could spark up some activity over the Caribbean in 3-5 days. Both the GFS and European models are indicating a strong tropical wave coming off Africa on the 26-27. This is a time where that CCKW could help to spawn an AEW. I'm thinking that the conditions are just a bit too hostile over the eastern MDR for immediate development, but I could see if the wave keeps its act together as it progresses across the central and western MDR, there could be some slow development.

[Amped]

Tropical storm Fay could be another example.

 

 

 

Florida is pretty flat and swampy with low drag, maybe just enough frictional convergence to put the flow in balance.  

[Amped]

David was one of my favorite cases since it surprised local forecasters here in 1979.

 

http://journals.ametsoc.org/doi/pdf/10.1175/1520-0493%281995%29123%3C3268%3APTCRIA%3E2.0.CO%3B2

 

An analysis is conducted from a potential vorticity (PV) perspective of the reintensification of Tropical Storm David over the northeastern United States in September 1979. David, a major long-lived hurricane, originated near the Cape Verde Islands in late August 1979. It made final landfall in Georgia on 4 September 1979 and weakened rapidly thereafter. The noteworthy aspect of David was its subsequent reintensification approximately 27 h after landfall as a warm-core disturbance in a weakly baroclinic environment. In this regard the redevelopment of David is unlike the classical extratropical transformation of a tropical storm in a strongly baroclinic environment that has been documented in the literature. The authors' analysis of the evolution of the dynamical tropopause subsequent to storm landfall revealed that David reintensified in response to “tropopause lifting” (upward displacement of the dynamic tropopause) ahead of a nondeepening and otherwise very weak upper-tropospheric disturbance. The “tropospheric lifting,” associated with both advective and diabatic warming poleward and eastward of David, resulted in steepening of the tropopause and compaction of the PV maximum associated with the weak upper-tropospheric disturbance. As the compacted upper-level trough accelerated north-eastward, the associated ascent and low-level horizontal convergence were rendered especially efficient in generating cyclonic vorticity by the neutral stability (relative to the moist adiabat) of the moist tropical air mass surrounding David and the presence of the preexisting low-level vorticity maximum associated with the remnant tropical storm circulation.

 

 

Hurricanes do a good job impersonating a southern stream shortwave in Miller A type scenarios. I can see a storm deepening as it phases and moves up the coast especially if it's not too deep to begin with. This looks pretty similar to what I can see on the NARR maps.

[Superstorm93]

Jeez thats rough...

 

From the guys at the Navy Post-grad Montgomery Research Group

 

 

No pouches will be tracked on Friday 19 July. The federal budget sequestration is being applied at the Naval Postgraduate School as furloughs every Friday during July-September. Employees are forbidden to work, under threat of termination.

 

http://www.met.nps.edu/~mtmontgo/storms2013.html

 

[Mike.Ventrice]

Jeez thats rough...

 

From the guys at the Navy Post-grad Montgomery Research Group

 

 

http://www.met.nps.edu/~mtmontgo/storms2013.html

 

 

Poor Mark Boothe... he's a really nice guy. Sucks to see this type of behavior Times are tough.

[Ed Lizard]

The Forbidden to Work thing, I suppose, is to anyone, whether a student in the Navy or a civilian employee unpaid for the day, from doing the work.  Like the cancelled military flyovers at sporting events and 4th of July picnics cancelled for active duty military, the Executive response to the sequester has been to make it as obvious and disruptive as possible.

[Ed Lizard]

Not well supported, but GFS moves a wave off Africa in about 3 days that is a depression in 8 days.  Euro has a very weak disturbance then, not sure if it is the same disturbance, Euro is closer to the Cape Verdes and it is hard to track things backwards to their source with what is available to the public from the ECMWF.

 

GFS depiction, the depression, judging from NCEP 4 panels, would be under light Easterly shear, 200 mb and 300 mb Easterlies just slightly stronger than 850 mb Easterlies.  GFS starts losing the disturbance beyond the resolution, and at hour 240, upper winds are strong North of the Greater Antilles per GFS.  Light Southerly upper flow South of the big islands, but low level flow is 20 to 30 knots, so any depression that would be in the MDR in 8 days would have to run a gauntlet of shear in the Caribbean to get to the other side.  Very slight hint from the US/Canadian NAEFS of this system in the Bahamas on July 31st.  Very mild suggestion.

 

 

 

Euro ensemble MJO looks decidedly low amplitude then, which I assume would be neither a negative or a positive for development. 

 

There is a disturbance moving rather quickly to the WSW in Africa.

[Srain]

The September CFSv2 monthly Precip anomalies are suggesting enhancement along the Gulf Coast and Yucatan during peak season. We will see.

[Ed Lizard]

You can call me a weenie, but I don't think the GFS development of a strong wave or even a depression in a week is  completely unfounded.

 

I will say, just a glance of the 192 hour 4 panel, that system is closing in on the Lesser Antilles, low level flow is getting stronger (divergent and the beginning of increasing shear), and the upper level Easterlies are Southerlies past the islands in the Caribbean, or the weakening of the system post truncation is probably not just an artifact of lower resolution.

 

Wishcasting beyond the reasonable limits of the model, on August 1st and 2nd on the lower res GFS four panels, this is entering the SW Caribbean, 850 mb winds are slowing (convergent), there is still a clear 700 mb moisture surge, and upper flow is weakly anti-cyclonic as the system approaches Belize.  

 

Sorry about my glass half full optimism for early August Central America opportunities for the people that chase.

[Ed Lizard]

'JamieP' just noted at the KHOU-TV 11 forum we have a new lemon.

 

 

Quick thoughts, 10% seems about right, maybe a tad generous.

 

This link is handy

http://tropic.ssec.wisc.edu/real-time/w ... oom=&time=

The low level feature is a little East of the upper level feature, which is actually providing decent upper level divergence and enhancing storms. Shear is a little high, but if the upper low gets just a shade farther from the low level trough SRain mentioned, shear would get much lighter, and the upper low might even induce a bit of an anticyclone above the low level trough, which could be favorable for development.

I'm just guessing it never gets far enough away from the upper low to develop, as I don't see any reliable guidance developing it, and it has been my experience, even if CIMMS products show apparently favorable shear, low level vorticity, lower convergence and upper divergence, if no model develops a tropical cyclone, a tropical cyclone doesn't form. Some people might call that 'model hugging', but I just haven't seen a system develop that at least one or two models aren't on a day or so in advance.

The least reliable and trusted of the modesl for TCs, the US NAM and Canadian, did forecast Edouard in 2008 before the generally more reliable models, so if I see what is apparently favorable conditions, if even a lesser regarded model shows development, I don't give up hope.

[Ed Lizard]

The Euro keeps things hostile over the Atlantic for the next ten days or so. Maybe beyond that we can get a strong enough

wave like Chantal to develop.

 

http://tropic.ssec.wisc.edu/real-time/sal/wvmid/movies/wvmid5.html

 

I see one obvious hurdle to anything Cape Verde-ish...

[TropicalAnalystwx13]

"You can call me a weenie, but I don't think the GFS development of a strong wave or even a depression in a week is  completely unfounded."

 

18z GFS develops a tropical depression in 87 hours that becomes a strong tropical storm by 192 hours before entering the northeastern Caribbean, crossing across Hispaniola, and moving up the East Coast.

 

I'd rather wait for later runs since the 18z has a history of being bullish, but I do think we should watch the East Atlantic for something similar to Chantal.

[Srain]

The 00Z NCEP TC Genesis Probabilities have remained rather stable over the past 4-5 day suggesting a strong wave crossing Africa will develops once it splashes into the Atlantic. We will see if this is the first of the Cape Verde storms to actually develop.

[Mike.Ventrice]

Hi all,

 

I'd be cautious with the GFS genesis- the wave does not exist yet and that fact alone makes me worried.

 

Anywho, I got in touch with Matt Potter and here's a link to his dissertation (we were discussing this a little above)

http://cstar.cestm.albany.edu/CAP_Projects/potter_thesis/Project19/Potter_Total%20Thesis.pdf

[usedtobe]

Hi all,

 

I'd be cautious with the GFS genesis- the wave does not exist yet and that fact alone makes me worried.

 

Anywho, I got in touch with Matt Potter and here's a link to his dissertation (we were discussing this a little above)

http://cstar.cestm.albany.edu/CAP_Projects/potter_thesis/Project19/Potter_Total%20Thesis.pdf

 

 

Glad to see some research into Camille.  Prior to me retiring I had showed Louis U. some really crude reanalysis data and previous research that suggested a jet streak, frontogenesis played a role in the heavy rains over VA.  I'm sure terrain also played a big roel for Nelson county.  It's nice to see research into the case as something like that is likely to happen again sometime down the road. 

[TropicalAnalystwx13]

The wave the GFS develops has been tagged as a pouch.

 

P12L
10N, 1W
700 hPa


ECMWF: The hovmoller signal is quite distinct. However, tracking a pouch is more difficult. For the first couple days, I track a tiny OW max (one of many over west Africa). Upon reaching the Atlantic, P12L becomes difficult to track, with little to no OW max or trough in the immediate vicinity. About a day later, a circulation is definitely spinning off the African coast, in roughly the area where P12L should be, but it never has a clear center, and the fact that P12L weakens so much during the middle portion of the forecast would make for a few too many "guess" points to get to this circulation. I stop tracking at the coast, but keep in mind that ECMWF does attempt to spin up something off the coast not long thereafter.

GFS: Easily tracked pouch the entire 120 hours. P11L, which is west of P12L, weakens as P12L approaches it. OW increases as P12L moves off of Africa.

UKMET: While ECMWF is only hinting at starting to agree with the bullish GFS, UKMET has jumped on the bandwagon. (Interesting since UKMET had no positions at all for P12 in yesterday's 00Z forecast.) UKMET does weaken P12L a little as it leaves Africa, as well as on Day 5 over the central Atlantic, but otherwise, UKMET depicts a distinct pouch all 120 hours.

[bluewave]

The wave the GFS develops has been tagged as a pouch.

 

P12L

10N, 1W

700 hPa

ECMWF: The hovmoller signal is quite distinct. However, tracking a pouch is more difficult. For the first couple days, I track a tiny OW max (one of many over west Africa). Upon reaching the Atlantic, P12L becomes difficult to track, with little to no OW max or trough in the immediate vicinity. About a day later, a circulation is definitely spinning off the African coast, in roughly the area where P12L should be, but it never has a clear center, and the fact that P12L weakens so much during the middle portion of the forecast would make for a few too many "guess" points to get to this circulation. I stop tracking at the coast, but keep in mind that ECMWF does attempt to spin up something off the coast not long thereafter.

GFS: Easily tracked pouch the entire 120 hours. P11L, which is west of P12L, weakens as P12L approaches it. OW increases as P12L moves off of Africa.

UKMET: While ECMWF is only hinting at starting to agree with the bullish GFS, UKMET has jumped on the bandwagon. (Interesting since UKMET had no positions at all for P12 in yesterday's 00Z forecast.) UKMET does weaken P12L a little as it leaves Africa, as well as on Day 5 over the central Atlantic, but otherwise, UKMET depicts a distinct pouch all 120 hours.

 

The Euro has a robust wave through 84 hours, but the convection weakens right after that in the more stable conditions than normal.

 

[TropicalAnalystwx13]

The previous two runs of the GFS have dropped the wave after showing robust development. That alone doesn't mean the wave can't develop, but it certainly reduces the chances even further than what they were. I'm still going to watch it, but...

[metalicwx366]

The previous two runs of the GFS have dropped the wave after showing robust development. That alone doesn't mean the wave can't develop, but it certainly reduces the chances even further than what they were. I'm still going to watch it, but...

Mike Ventrice was right. The GFS did this earlier in the month with a wave behind Chantal that it kept trying to make a significant storm and him and Phil had discussed it. Now with this wave Mike said to be cautious of the Genesis the model is showing and looks like he was correct .

[GaWx]

Aug. geneses 1995-2012 by MJO phase:

 

 

 

MJO phase: MJO # days; # TC geneses/# MDR TC geneses/# US direct H hit TC geneses;      TC geneses per day/MDR TC geneses per day/US direct H hit TC geneses per day

 

1: 63; 9/5/1;  14%/8%/2% (Bret ’99)

2: 88; 17/8/3; 19%/9%/3% (Isaac ’12, Gustav ’08, Bonnie ’98)

3: 32; 12/8/1; 38%/25%/3% (Fran ’96)

4: 15; 0/0/0; 0%/0%/0%

5: 34; 5/4/0; 15%/12%/0%

6: 36; 7/5/1; 19%/14%/3% (Charley ’04)

7: 14; 1/0/0; 7%/0%/0%

8: 22; 4/2/2; 18%/9%/9% (Frances ’04, Earl ’98)

C: 254; 25/13/2; 10%/5%/1% (Irene ’11, Katrina ’05)

 

ALL: 558; 80/45/10; 14%/8%/2%

 

- Note the high %'s of both TC geneses and MDR TC geneses for phase 3 and the high % of direct H hits from geneses during phase 8 during August. However, phase 8's #'s are low and have low statistical credibility.

 

- Phases 1 and 2 make up half of the outside of circle August days since 1995.

- Also, note that phase 2 has had ~six times as many days in August during 1995-2012 as each of phases 4 & 7

- So, normalization was very crucial!

 

- Note that being within the circle (“C”) has resulted in below avg. %’s though Katrina came from there.

[TropicalAnalystwx13]

Mike Ventrice was right. The GFS did this earlier in the month with a wave behind Chantal that it kept trying to make a significant storm and him and Phil had discussed it. Now with this wave Mike said to be cautious of the Genesis the model is showing and looks like he was correct .

It wouldn't totally surprise me to see the GFS pick the wave up again. The main reason the model dropped it appears to be because it emerges at a higher latitude, making it more susceptible to cooler sea surface temperatures, higher wind shear, and faster trade winds.

We'll just have to wait and see. Probably won't get a full-blown hurricane like the GFS was suggesting, but I wouldn't be surprised to see a Chantal-type storm. Wave has a very large axis, and the southern part of it could develop eventually.

[thewxmann]

If I had a penny for every time the GFS blew up a CV storm falsely, I'd be able to retire right now.

[Derecho!]

If I had a penny for every time the GFS blew up a CV storm falsely, I'd be able to retire right now.

 

Actually I'm pretty amazed at how rarely it does so.

 

No comparison with the "boguscane" plague of the AVN/MRF. That was worse than the CMC is now.

[GaWx]

Actually I'm pretty amazed at how rarely it does so.

 

No comparison with the "boguscane" plague of the AVN/MRF. That was worse than the CMC is now.

 

 The infamous 5/15/01 AVN./MRF major mod was mainly trying to reduce the # of boguscanes. This worked for that but it also created a strong cold bias as it had actually been slightly warm biased prior to the 5/15/01 change.

[icebreaker5221]

I wouldn't worry about a no-show to close out July.  I know it's said every year, but it's worth repeating that the season doesn't really start till Aug 1.  Anything before then is just bonus.