ATL: DANNY - Remnants - Discussion

[stormlover2013]

Models struggle with troughs during this time of the season, usually they aren't as strong as models predict 3-5 days out

[txwatcher91]

Two interesting observations about Danny so far. First, he appears to be slowly growing in size both in convection increasing in coverage as well as better outflow being established to the north. Second, the shear in front of him on the CIMSS tendency map has actually been decreasing while the band of high shear is getting narrower and less intense. Models are also trending upwards in intensity with most all of them now keeping this as a TS then restrengthening. Shear forecasts are always incredibly difficult to forecast and volatile and it appears Danny isn't encountering quite as much as was earlier thought. The rest of today will be telling since he should be moving into the 30kt shear but for now he's holding together fairly well while expanding some in size.

[CYCLONE MIKE]

Leaning towards gfs for late next week. Think the euro will come around in a few days. Going to be a lot going on (energy wise) due to the wpac typhoons becoming absorbed into the northerly stream flow. Going to be a very unstable pattern shaping up

The only problem I have with that is how consistently wrong the GFS has been with large scale patterns in the longer range. The euro is not always accurate but not completely opposite reality as the GFS has been. I've been entertained on Weatherbell by JB showing GFS maps run to run and just how horribly inconsistent it is.

We shall see.

Been straining my brain trying to remember back to last year when this similar thing happened. Any model gurus remember which was most consistent in showing everything how transpired?

[Siker]

Leaning towards gfs for late next week. Think the euro will come around in a few days. Going to be a lot going on (energy wise) due to the wpac typhoons becoming absorbed into the northerly stream flow. Going to be a very unstable pattern shaping up

The only problem I have with that is how consistently wrong the GFS has been with large scale patterns in the longer range. The euro is not always accurate but not completely opposite reality as the GFS has been. I've been entertained on Weatherbell by JB showing GFS maps run to run and just how horribly inconsistent it is.

We shall see.

Been straining my brain trying to remember back to last year when this similar thing happened. Any model gurus remember which was most consistent in showing everything how transpired?

I believe it was the GFS who caved to the Euro's further east scenario. I'll go skim the Cristobal threads real quick.

[Gustywind]

Remember my carib friends if you have any infos related to Danny arrival, don't forget to post it in our tent viewtopic.php?f=24&t=85676&st=0&sk=t&sd=a
Thanks

[wzrgirl1]

I am keeping one eye on this after seeing the new model intensity changes. They must be seeing something that has yet to be forecast yet. If it is a trend then both eyes. Not writing this off yet.

[Siker]

After checking, the Euro was the first to pickup on Cristobal's recurvature, FWIW.

[wxman57]

I am keeping one eye on this after seeing the new model intensity changes. They must be seeing something that has yet to be forecast yet. If it is a trend then both eyes. Not writing this off yet.

I'm not sure what model you're looking at, but the dynamic models are all indicating steady weakening of Danny. The Navy NOGAPS (NAVGEM) model is the only one indicating otherwise, and it's terrible at track and intensity.

[NDG]

As long as the HWFI keeps showing Danny weakening into a tropical wave after passing PR/Hispaniola I am not too worry about it maintaining TS status into the southern Bahamas, it was the only dynamical model that when Danny was an invest and even a named TS that was persistent in bringing Danny into a Cat 3.
But then again it goes by the GFS's forecasted large scale UL forecast so if the GFS is showing a trough to come down to FL creating windshear over the Bahamas the HWRF is going weaken it.

[txwatcher91]

I am keeping one eye on this after seeing the new model intensity changes. They must be seeing something that has yet to be forecast yet. If it is a trend then both eyes. Not writing this off yet.

I'm not sure what model you're looking at, but the dynamic models are all indicating steady weakening of Danny. The Navy NOGAPS (NAVGEM) model is the only one indicating otherwise, and it's terrible at track and intensity.

For the next 72 hours yes, however after that quite a few bump the intensity up again as it nears the Bahamas and assuming it goes north of PR and Hispaniola. They also don't weaken it as much as they did yesterday, shear appears a little less than originally thought.

[Gustywind]

NEW: Hurricane Danny weakens a little more remains a category 2 dangerous system

22 Aug 2015 |
Published in Soualiga News Today

http://www.soualiganewsday.com/local/so ... ystem.html


SINT MAARTEN – At 5.00AM Saturday, August 22, the National Hurricane Center (NHC) reports that Hurricane Danny continues to weaken, but remains a dangerous category 2 hurricane. Danny is expected to become a tropical storm on Sunday, 23 August.


Danny was located 740 miles east of the Leeward Islands and has sustained winds of 100 miles per hour down from 110 miles per hour.


Danny’s forward speed remains unchanged at 10 miles per hour and the hurricane continues on a west north-west track towards the islands. An increase in forward speed is expected later today-Saturday with the system taking a more westerly track.



Tropical storm watches will likely be required for portions of the Leeward Islands (from Antigua & Barbuda to Anguilla which includes Saba, Sint Maarten, St. Eustatius, St. Kitts & Nevis, St. Barths, Montserrat) on Saturday, 22 August.



Hurricane Danny is approaching an unfavourable environment and it should become a tropical storm on Sunday, August 23 according to the NHC.



Currently hurricane force winds extend outward to 15 miles and tropical storm force winds 60 miles.

[Ntxw]

I'm not sure what the disagreement has been in the long term forecast (beyond 5 days)? It's never going to match exactly with the nature of the time frame anyway. Both the Euro/GFS/Ensembles are generally in agreement an eastern conus trof will impact, west or east it's still there. Likely assisted by the recurve of Atsani and Goni. We're talking about a rare 2-3 Sigma wave breaking event in the North Pacific which supports a very deep trough. If it was in the Bahamas by then, odds are the coming trof would shunt it out anyway. Assuming guidance consensus is correct.

[Sanibel]

GFDL clears the islands by a good margin and brings an intensifying 83 knot cyclone into the Bahamas at the end of the run.


Current SST's are marginal.

[NDG]

GFDL clears the islands by a good margin and brings an intensifying 83 knot cyclone into the Bahamas at the end of the run.


Current SST's are marginal.

To what area are you referring to on SSTs?

[MGC]

I not so sure I'm ready to accept such a deep trough over the GOM this time of year. I know it can happen as in 2004 which shunted Hurricane Charley to the NNE. Danny might just be a remnant low by the time the cyclone is near Hispaniola. But, if the cyclone avoids land and passes to the north of the Greater Antilles with its circulation intact it could find a favorable upper level environment as depicted by the EURO and reintensify. Currently, it looks like Danny has its moisture feed from the south cut off looking at the WV loop. Danny looks like an island surrounded by dry air now. Shear is lurking ahead. Hopefully, between the shear and dry air all the islands get are some squalls and much need rain. Here is to a slow agonizing death Danny boy......MGC

[NDG]

It sounds like a good compromised forecast for now.

The intensity forecast becomes lower confidence at days 4 and 5 due to
the uncertainty in how much land Danny will encounter, disagreements
between the dynamical models over the forecast shear, and continued
divergence between the models forecasting Danny to dissipate and the
models forecasting it to survive. The latter part of the forecast
compromises between these extremes by showing a continued weakening
trend.

http://www.nhc.noaa.gov/text/refresh/MI ... 2043.shtml

[Sanibel]

My SSD map says SST's are only around 28c in current area.

[northjaxpro]

I'm not sure what the disagreement has been in the long term forecast (beyond 5 days)? It's never going to match exactly with the nature of the time frame anyway. Both the Euro/GFS/Ensembles are generally in agreement an eastern conus trof will impact, west or east it's still there. Likely assisted by the recurve of Atsani and Goni. We're talking about a rare 2-3 Sigma wave breaking event in the North Pacific which supports a very deep trough. If it was in the Bahamas by then, odds are the coming trof would shunt it out anyway. Assuming guidance consensus is correct.

I agree if Danny is somehow around by this time next week, it will get picked up eventually. Other than the factor of if Danny is still around then, if that is the case, it is just a question of timing regarding when and where it will get picked up. The latest GFS shows a deep trough across the eastern U.S. which would pick up anything left of Danny before the system reaches 75 degrees Longitude. EURO with its latest run out 144 hours, is potentially showing a scenario that may allow anything left of Danny to move a bit farther west before feeling the impact of the trough with a 200 mb ridge in place near the Bahamas.

[Sanibel]

It sounds like a good compromised forecast for now.

Sounds like a recipe for disaster in the prime spot in the basin where the Labor Day storm formed and the potential for a blown missed forecast.

[tropicwatch]

NHC has issued its 11am advisory but the forecast graphic hasn't been updated.