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The 2017 Atlantic Hurricane Season Thread

George BM

By George BM,
in Mid Atlantic

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showmethesnow

showmethesnow

Posted
Posted
17 minutes ago, H2O said:

CMC is on crack right now.  While the GFS might be underplaying the tropics some what the Canadian shows just seems way out there.  3 TSs all within 500 miles of each other?  lol

When it is the only game in town I guess you have to hold your nose and hug it.

Edit: And Justine Burk swears by it. So there is that. :D

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showmethesnow

showmethesnow

Posted
Posted
59 minutes ago, WxWatcher007 said:

I won't be put in the position of defending the Canadian :P 

Aside from the crazy Canadian output after hour 120, I think all options are on the table on all the guidance. We really have to watch how resilient 92L is the next few days. The current low to the north can do damage, but on the GFS, I think I can identify what keeps 92L from developing until the GOM (where it stalls and develops gradually). 

G2qUzk.gif

On the GFS, the current low to the north drives shear and dry air, but in 24 hours, the GFS develops what looks like a TUTT that drives south and gets tangled up with 92L. Much like what happened with Gert, when the TUTT and tropical wave are tangled, meaningful development doesn't happen. 

e9eFTA.gif

I really don't think it's that unreasonable for a weak low to be approaching the Bahamas, and then gradually develop (like the Ukie suggests) as it gets into a more favorable environment. It's also not unreasonable to think that 92L gets choked by dry air and cut into pieces by shear. This is a vigorous wave though. Development is still a coin flip IMO and I don't think any single piece of guidance has a good handle on it. 

The shear is already getting to 92L. Dry air is at bay, for now...

Just had a chance to glance over your speculation on whether it was a TUTT that was impeding the development on the GFS. Seems that the CMC has that same feature as well with a very similar evolution in the near term as well. Also looking at the 850/200 mb shear, the shear on the CMC looks marginally stronger and less favorable then what we see on the GFS. So possibly this is not the deciding factor in development or quite possibly we are seeing a divergence between the models on how the coding handles the relationship between the TUTT and the invest? 

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das

das

Posted
Posted

Decent rain producer in the southern Antilles:

http://barbadosweather.org/Composite/kidbuuComposite_displayer.php?Product=Reflectivity&Sector=EC_Bar&Composite=Sabre&PlanetOfTheApes=1503064848

 

Love the roiling cloud top activity in the low shear environment just west of the islands (http://tropic.ssec.wisc.edu/real-time/atlantic/winds/wg8sht.GIF) this morning:

http://rammb.cira.colostate.edu/ramsdis/online/loop.asp?data_folder=goes-16/mesoscale_01_band_02_sector_03&width=1000&height=1000&number_of_images_to_display=40&loop_speed_ms=80

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high risk

high risk

Posted
Posted

quick comment:   do NOT use the 18z GEFS for tropical systems until a bug is fixed.   The GEFS SST initializes off of the GFS, and the GFS now uses an SST which is allowed to warm up during the day and then cool back down at night.     The GEFS at 18z therefore initializes with warmer water, but it doesn't have the code to cool down at night, so the water stays at this extra warm temperature throughout the run, and the run is really active in the tropics compared to other cycles.    A fix to use the base-state SST in the GEFS is coming soon.  

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showmethesnow

showmethesnow

Posted
Posted

 

42 minutes ago, WxWatcher007 said:

Can't look closer right now so I'm not sure. I see a few pros reading the thread too. Folks, if my analysis is ever off please do set me straight.

I REALLY love learning about this stuff and your posts are helpful to us commoners. 

Sorry @WxWatcher007. I didn't mean to imply that your analysis was wrong. It very well could be spot on and in fact I actually lean towards your thoughts on why we are not seeing development on the GFS. I think what we are seeing is more an issue of how both models are handling this feature and its interaction with the invest more then anything else.

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yoda

yoda

Posted
Posted

Looks like 92L is going to go goodbye soon per 2pm NHC TWO:

Quote 

1. Shower and thunderstorm activity associated with an area of low
pressure located about 600 miles east-northeast of the Leeward
Islands continues to show signs of organization.  However,
upper-level winds are becoming less favorable, and the chances for
a tropical cyclone to form are diminishing.  The low is expected to
move west-northwestward at about 20 mph during the next few days,
and interests in the northern Leeward Islands should monitor the
progress of this disturbance.
* Formation chance through 48 hours...medium...60 percent.
* Formation chance through 5 days...medium...60 percent.
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Vice-Regent

Vice-Regent

Posted
Posted
10 minutes ago, WxWatcher007 said:

I almost want to take back every nice thing I've said about the Canadian:yikes:. It's shown that it can't handle a compliment. 

On the bright side, at least the weenie in me gets an X rated show tonight.

Going to be boring for the casual watchers the next few days. Harvey and 92L are in hostile territory. Probably won't see much sizzle until at least Sunday or Monday.

Bob Chill's Chesepeake Bay runner. For what it's worth, 92L seems to be following the Canadian in terms of intensity and track. I see no indications of dissipation, just a vigorous wave waiting for a favorable window. I am under the impression that it should of been classified as a TD, maybe in a post-season review.

Having UKMet support for this system is a big red flag in my book. The GFS and Euro have been running conservative on TC intensity and the Euro falsely developed 93L it would appear.

gem_mslp_pcpn_atl_38.png

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Vice-Regent

Vice-Regent

Posted
Posted
3 minutes ago, Amped said:

Cause the CMC said so

Not necessarily, there will be frontal enhancement going in the Bahamas region. I see it on the GFS ensembles as well. We know from history that waves don't vaporize, they can interact with fronts easily. Hurricane Andrew formed from a wave weaker than 92L.

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showmethesnow

showmethesnow

Posted
Posted

CMC is a trooper. Still likes 92L with it bringing a 971 mb Cane off the eastern seaboard. GFS and Euro not so much though it does look like they make a feeble attempt to do something with it in the longer range.

Radar at this point is somewhat unimpressive with it looking to be a disorganized mess. Positive is that it is still popping convection and the latest convection looks as if it may be over what looks to be the center of circulation though that is a guess more then anything else.

Edit: May have spoken to soon, the 06Z GFS has just rolled in and it now produces a 970-980 mb cane a distance off the southeast coast.

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Vice-Regent

Vice-Regent

Posted
Posted

I like where we stand in regards to 92L. Not yet sure if the homebrew will come directly from 92L but you can be sure something will brew up down there. The H5 pattern on the 0z Euro is ominous and the Euro tries to make a run at Homebrew for the first time. GFS intensity with Euro H5 would be a huge win if you like tropical.

I would be pessimistic for red meat tropical if I lived in Florida. But here? not at all, we have plenty of time. Continuing a trend in recent years of that region missing out on the larger tropical threats to the north.

Edit: Very sick 5 minute GOES-16 loop with the circulation readily visible. I love these young systems, good way to study TCs.

http://rammb-slider.cira.colostate.edu/?sat=goes-16&sec=conus&x=8680&y=5832&z=3&im=12&ts=1&st=0&et=0&speed=90&motion=loop&map=1&lat=0&p[0]=16&opacity[0]=1&hidden[0]=0&pause=0&slider=-1&hide_controls=0&mouse_draw=0&s=rammb-slider

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yoda

yoda

Posted
Posted

12z GFS develops 92L just north of Bahamas Day 5-6... but quickly moves it NE thereafter and out to sea... and thats all the 12z GFS has tropical-wise this run

One of these days the 12z CMC will be right :lmao: (makes 92L a hurricane on a nor'easter like track up the East Coast lol)

12z UKIE looks like a way weaker version of the 12z CMC fwiw

 

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yoda

yoda

Posted
Posted
59 minutes ago, yoda said:

Recon on the way/or at ex-Harvey 

Special Tropical Weather Outlook
NWS National Hurricane Center Miami FL
420 PM EDT Sun Aug 20 2017

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

Special Tropical Weather Outlook issued to update discussion on
the remnants of Harvey.

Updated:  An Air Force Reserve Unit Hurricane Hunter aircraft
investigating the remnants of Harvey found that the system still
lacks a well-defined center of circulation, and so far there is no
indication of winds to tropical storm force.  Satellite images
indicate that the associated showers and thunderstorms have changed
little in organization since earlier today.  Gradual development of
this system is possible, and it could become a tropical cyclone once
again while it moves west-northwestward across the northwestern
Caribbean Sea, near the northern coast of Honduras, during the next
day or two.  The system is expected to reach Belize or the Yucatan
Peninsula on Tuesday, and then move into the Bay of Campeche by the
middle of the week, where redevelopment appears more likely.
Interests in northern Nicaragua, Honduras, Belize, and the Yucatan
Peninsula should monitor the progress of this system.
* Formation chance through 48 hours...medium...50 percent.
* Formation chance through 5 days...high...70 percent.
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yoda

yoda

Posted
Posted
30 minutes ago, Wonderdog said:

From midday Friday to Monday morning, the system sits nearly stationary off the SE coast and then begins to strengthen rapidly and move NE. Might be fun to track.

Meh... no real chance of any interaction with the East Coast, another boring fish

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yoda

yoda

Posted
Posted

00z CMC is da bomb:

-- Redevelops Harvey in the BoC into a pretty decent hurricane and strikes the Central MX coastline

-- Develops 92L right away (as in TD in next 36 hrs) and takes it across S FL.  Comes out the other side of FL into the GOM and quickly develops into a hurricane.  Abrupt stop in W movement around hr 78, then begins to move NE and second landfall near Tampa.  Irene then moves up FL and comes out into the Atlantic Ocean somewhere near Flagler/Daytona Beach.  Irene then grabs some Gulf Stream and deepens quickly and Day 8-10 seems some outer bands could make it to the Outer Banks and SE New England as Irene moves ENE

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tstate21

tstate21

Posted
Posted
9 minutes ago, yoda said:

Can I get 12z CMC to go please with a double side of lulz?  Outer Banks landfall with Irene (I think?) at 198

Technically it would be Irma, Irene was retired back in 2011 - but yeah the CMC has been throwing out some ridiculous runs over the past week. 

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