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wxmx

Tropical Storm Danny

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Will be interesting to see if the increase in intensity this evening can help inch the storm north of the islands.  The Caribbean isn't just sheartastic this year, it's also much less juiced than the subtropics.  There's a lot of gas in the waters off of Florida.

 

http://wxmaps.org/pix/hurpot.html

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Which operational model has a more realistic handling of the low-level ridging north of Danny through day five: the ECMWF or the GFS? Why? (My personal guess is a blend of the ECMWF and GFS, since the ECMWF, through its bias, likely makes Goni and Atsani too deep by day five, thereby making a "wavier" N Hemisphere pattern that causes a more elongated subtropical ridge, even though the ECMWF has a superior handling of the overall pattern.) How the models handle the ridge would certainly affect whether Danny is a Caribbean cruiser or goes over/north of the Leewards, Puerto Rico, and Hispaniola. It would also affect how much dry air Danny would potentially ingest, given that the GFS indicates a more moist mid-level environment outside the ITCZ than does the ECMWF. Personally, I already believe that the 0300Z (08/18) NHC forecast for 90 kt in five days is far too high...I would go with 60-65 kt as a compromise between the most bullish (statistical) and bearish (dynamical) guidance, given the likely influence of dry air. Danny could easily end up even a bit weaker than this if the ECMWF forecast verifies, with its stronger low-level trades serving to increase vertical wind shear--a detrimental trend for sub-hurricane systems nearing the islands.

 

I could be wrong, but when comparing the ECMWF to the GFS, I would give the ECMWF a nod when looking at the influence of environmental conditions on developing systems. Given its superior convective scheme, the ECMWF may better capture the effect of mid-level dry air on the developing core of a weak to moderate tropical storm. Once Danny gradually leaves the ITCZ over the next few days, it could really begin to struggle against much lower relative humidity to its northwest. The NHC mentions short-term rapid intensification or slower deepening due to dry air as the two options. I would suggest a third: that Danny fails to develop beyond a mid-range tropical storm (50-55 kt) and then unravels into an open wave as it encounters stronger low-level easterlies near the islands in five days. We've seen other systems similar to Danny form in the MDR and then fail to intensify as much as expected, thanks to the unexpectedly large impact of dry air on the inner core of the system. I can't recall the last time I've seen a TC strengthen significantly in an environment as dry as Danny's. Plus, the spread between the statistical and dynamical intensity guidance has widened over time.

 

As far as Danny's only reaching moderate TS status before dissipating, I wouldn’t necessarily go with that solution, but I would give it a 40% chance of occurring, with the highest chance (50%) that Danny slowly intensifies to 60-65 kt by the end of the NHC forecast period. 10% would be other solutions.

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Drz1111, on 18 Aug 2015 - 10:21 PM, said:

Will be interesting to see if the increase in intensity this evening can help inch the storm north of the islands.  The Caribbean isn't just sheartastic this year, it's also much less juiced than the subtropics.  There's a lot of gas in the waters off of Florida.

 

http://wxmaps.org/pix/hurpot.html

up to 45kts 50mph at 11pm

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In the super long term fantasy land of the GFS I see Danny passing between outer banks and Bermuda as a TS or Hurricane during the week of September 1st.  

 

That track is the holy grail for swell chasers/ surfers like  myself.  Thats like Hurricane Bill 2009 material.... 

 

 

I need to schedule time off.  

 

I know it is fantasy land.. but if it does happen.. do you guys think thats a realistic time frame?  I have a hunch it would be a little earlier than that... but I dont really know anything.  

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Downstream influence from typhoons Goni and Atsani would indicate a mean weakness off the East Coast in about five to seven days as Danny nears the area, suggesting than an intact Danny would curve east of the mainland United States...correct? (As an aside, does anyone know what happened to "Hart"/nineinchnails with his good overviews of downstream patterns over upcoming weeks? Feel free to send me a message.)

 

As an aside, the GFS has been consistently intensifying Danny too quickly and, as I have mentioned, apparently underestimated the impact of dry air on the structural organization of the cyclone. The fact that the GFS shows less impact from vertical shear in three days and beyond is related to the model's showing a much deeper Danny building a robust anticyclone aloft. That won't happen, making the ECMWF solution more realistic.

 

I'd go with 60-65 kt tops for Danny's peak, though 50-55 kt may be more plausible, given the possibility that the dry air won't mix out as Danny leaves the ITCZ.

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In the super long term fantasy land of the GFS I see Danny passing between outer banks and Bermuda as a TS or Hurricane during the week of September 1st.

That track is the holy grail for swell chasers/ surfers like myself. Thats like Hurricane Bill 2009 material....

I need to schedule time off.

I know it is fantasy land.. but if it does happen.. do you guys think thats a realistic time frame? I have a hunch it would be a little earlier than that... but I dont really know anything.

Highly unlikely with the now weaker storm.

Bill was a beast cat 3 with a huge area of hurricane fource winds in our swell window. It also had almost perfect wave setup as the track of the storm kept swell moving with the strongest winds leading to enhanced wave heights.

That swell was the biggest i have surfed on Long Island in 20 years of surfing. Easily 15 foot on the face. The craziest thing is the swell peaked over night so we never even saw the biggest.

The swell peaked at the Long Island bouy at around 20 feet at 20 seconds. Just not something you see on the east coast. And would easily have the Eddie running in Hawaii. (Better bottom an no continental shelf makes a swell that size break 40' plus)

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Highly unlikely with the now weaker storm.

Bill was a beast cat 3 with a huge area of hurricane fource winds in our swell window. It also had almost perfect wave setup as the track of the storm kept swell moving with the strongest winds leading to enhanced wave heights.

That swell was the biggest i have surfed on Long Island in 20 years of surfing. Easily 15 foot on the face. The craziest thing is the swell peaked over night so we never even saw the biggest.

The swell peaked at the Long Island bouy at around 20 feet at 20 seconds. Just not something you see on the east coast. And would easily have the Eddie running in Hawaii. (Better bottom an no continental shelf makes a swell that size break 40' plus)

So hurricane Bill was the first time I ever went out in real swell. At that time I didn't know how to do anything but I saw guys getting out with boogie boards and fins. So I went out and bought some gear paddled out almost died about 4 times before I got to the point where the waves were breaking over my head anymore and probably 10 minutes later caught the best wave of my entire life hands down. I was completely hooked after that

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So hurricane Bill was the first time I ever went out in real swell. At that time I didn't know how to do anything but I saw guys getting out with boogie boards and fins. So I went out and bought some gear paddled out almost died about 4 times before I got to the point where the waves were breaking over my head anymore and probably 10 minutes later caught the best wave of my entire life hands down. I was completely hooked after that

That's nuts. Definitly not a swell for beginners!!!

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That's nuts. Definitly not a swell for beginners!!!

Oh yeah.. Like I am really good swimmer and I have boogie boarded before... But never where you had to actually paddle in to the shoulder of a wave... I am pretty sure the wave was 10 plus feet. The one thing I remember was when I was trying to get out and would get caught in the break zone... The water would hold you down... Its like you couldn't figure out which way was up. Dude I didn't even know that "duck diving" was a thing. When I finally got out it was because I timed it during a lull between sets and paddled for dear life!!!! Probably the best memory of my life.

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Where is Josh and team?

I had wondered the same thing some months ago when he did not start the Atlantic Tropical thread and I noticed he was not posting much at all lately and wondered if it was the criticism he so often got about the ethics of chasing, so I Googled ICyclone and found a bit of chatter on Facebook of which I do not partake, don't like their politics, don't have time for the drama.  I just Googled ICyclone and found the post below at Facebook, Josh is in the Pacific. The Pacific is a lot more fun than the Atlantic whether it is cyclones or surf. Use to live on Oahu, Hawaii back in the 70's so I can appreciate the talk about waves in this thread. Pipeline beach will always be my most favorite place on the Planet. 

Hey from... JAPAN. Yeah. Wasn't gonna go for it, but just couldn't help it-- I have the cyclone itch, I need to scratch it-- so I hopped on a flight from L.A. and here I am. What sold me was Typhoon GONI's structural changes yesterday. The new, huge eye and truck-tire structure make the cyclone's core a large target (good for island chasing) and also more stable. I've noticed over the years that pinhole eyes and tightly-wound eyewalls are sexy, but they can disintegrate in seconds-- that sexiness is fragile-- whereas these fat-core systems are more durable and just built to last. (That having been said, a little dry air has gotten in recently.) So here I am in Tokyo. And now it's time for my favorite game: Island Roulette.

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If Danny were a more typical-sized cyclone and had another two days or so, it would potentially have enough time to become a substantial hurricane and form a large anticyclone overhead, potentially counteracting the moderate to strong TUTT-generated westerlies lurking to its northwest. However, Danny has less than 24 hours to go before it encounters those westerlies (strong vertical shear), thereby halting significant intensification in its tracks. You can already see signs of shear impinging on outflow in the western semicircle. Given the small size of the storm, I think that Danny will likely peak sometime later today or overnight before weakening rapidly starting tomorrow. The NHC shows a peak around 12Z tomorrow, based on a blend of the dynamic and statistical guidance, which I think is too late, given that the ECMWF already shows less favorable conditions and signs of weakening overnight.

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