Nate

[olafminesaw]

 

[NavarreDon]

Didn't see enough from recon to go with a TS.

SUMMARY OF 500 PM EDT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...12.5N 82.5W
ABOUT 55 MI...85 KM W OF SAN ANDRES ISLAND
ABOUT 180 MI...290 KM SSE OF CABO GRACIAS A DIOS ON NIC/HON BORDER
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...NW OR 315 DEGREES AT 7 MPH...11 KM/H
MINIMUM CENTRAL PRESSURE...1005 MB...29.68 INCHES

[NavarreDon]

Some interesting thoughts in the 5:00pm NHC disco!

Tropical Depression Sixteen Discussion Number   2
NWS National Hurricane Center Miami FL       AL162017
500 PM EDT Wed Oct 04 2017

Visible satellite images show that the depression has lots of
curved bands, although it is somewhat lacking any inner core
features. An Air Force Reserve Hurricane Hunter flew into the
depression this afternoon and found a well-defined circulation, with
maximum flight-level winds of 37 kt and SFMR values around 30 kt.
These data support keeping the intensity at 30 kt for this advisory.

Environmental conditions look quite favorable for strengthening over
the next few days, with low shear and very warm and deep water in
the path of the cyclone.  The various rapid intensification indices
are all higher than the last cycle, suggesting an increasing chance
of rapid intensification occurring.  The fly in the ointment,
however, is all of the potential land interaction, first over
Central America and then possibly over the Yucatan Peninsula.  As
a compromise, the intensity forecast is raised considerably from the
previous one during the first 3 days, but is still below some
guidance, such as the HWRF.

The depression continues to move slowly northwestward, steered by a
distant ridge over the southwestern Atlantic.  However the steering
pattern is forecast to change quickly tomorrow as a mid-tropospheric
trough over the Florida Straits moves across the northwestern
Caribbean into the southwestern Gulf of Mexico.  Southerly flow on
the eastern side of that trough should cause the cyclone to move
much faster to the north-northwest by Friday and northward into the
Gulf of Mexico on Saturday.  While there is some agreement on the
synoptic pattern, the model track agreement is rather poor, even in
the short term, with the GFS and ECMWF being 90 miles apart on the
forecast track as soon as 24 hours out.  This has profound
differences down the road, with the GFS-based guidance moving
considerably faster and to the left of the ECMWF and UKMET across
the Gulf of Mexico.  Overall, the guidance has generally shifted a
bit westward since the last cycle, so the latest points in the long
range have been adjusted in that direction.  At this point, I
wouldn't focus too much attention on the details of the long-range
forecast until the guidance comes into better agreement.  A G-IV
mission and Florida special soundings have been set up for tomorrow
to better determine the synoptic steering flow around the cyclone.

[the ghost of leroy]

2 hours ago, Ginx snewx said:

Wonder if Kush thinks the Euro gust potential is still bunk.it has 120+ gusts now in Florida

thanks for thinking of me.

[Roger Smith]

NAME for this one is Nate, next one: Ophelia -- let's hope it doesn't flatten any hamlets. 

[HKY_WX]

TCHP is insane right now in the NW Caribbean. Wonder if this will pull a Wilma once it reaches those waters and bomb out insanely.

[wxeyeNH]

and 18Z GFS basically says what RI?  1000mb low in the Gulf.  No big deal.  Didn't expect that! 

[wkd]

3 hours ago, Windspeed said:

But they don't forecast based on climatology. They forecast based on current synoptic pattern, features and steering flow, and their own modeling consensus.

 

Thank you, thank you, thank you

[Superstorm93]

8 minutes ago, wxeyeNH said:

and 18Z GFS basically says what RI?  1000mb low in the Gulf.  No big deal.  Didn't expect that! 

Its moving way too quickly in addition to the new GFS having a CI bias. Check the 850mb vort maps for the past few runs. 

[Hoth]

1 hour ago, Roger Smith said:

NAME for this one is Nate, next one: Ophelia -- let's hope it doesn't flatten any hamlets. 

She's a green girl, unsifted in such perilous circumstances.

[Hoosier]

Every member of the 18z GEFS except 2 make landfall in Louisiana, and the 2 that don't are in Texas.

Would've been nice to see some eastern members on there, lol

[NavarreDon]

Looks like some CDO might be forming on the IR. We might have Nate sooner than later.

[Bob Chill]

1 hour ago, Hoosier said:

Every member of the 18z GEFS except 2 make landfall in Louisiana, and the 2 that don't are in Texas.

Would've been nice to see some eastern members on there, lol

Gefs never has much spread with TCs this season. Especially inside of d6-7. It's done this with every storm this year. If the op shifts east next run every single ens member will do the same. It's not how ens spread is supposed to work unless the op and ens are lasered in on the correct track at long leads. But that hasn't been happening obviously.

Not sure why the gefs has been doing this but my guess is it has something to do with the last upgrade. It needs to be fixed.  I'm not going to trust the ens this winter either. It's going to make a lot of snow weenies mad.  Lol. No doubt about that. 

[Superstorm93]

Radar out of San Andres 

 

http://meteorologia.aerocivil.gov.co/image/inline/23822380 

 

[40/70 Benchmark]

I think Florida needs to act quickly and hope for the best:

http://easternmassweather.blogspot.com/2017/10/more-tropical-troubles-brewing-for.html

[HoarfrostHubb]

What's the record for majors landfalling on US territory in one year?

[ncforecaster89]

22 minutes ago, HoarfrostHubb said:

What's the record for majors landfalling on US territory in one year?

Four "major" hurricane landfalls in one season, occurred in 2005: Dennis, Katrina, Rita, and Wilma.  I believe there have been 2 or 3 other years with three "major" H landfalls in the USA.

[Random Chaos]

After watching and amateur forecasting tropical systems for the past 15 years, I have two rules of thumb when it comes to tropical systems in this part of the Atlantic:

1. Any system that is not yet a Tropical Storm for at least 6-12 hours we really have to take the models with a grain of salt. The models do a horrible job at initializing storms that haven't been declared at least 35mph closed lows at the time that the models initialized.

2. Any system that enters the Gulf of Mexico is (a) probably going to hit land somewhere and (b) has the potential to seriously outperform the intensity forecasts with a strong chance of rapid intensification if shear is low enough.

 

With those two elements in mind, a quick check of the 18z and 12z model runs (as we wait for the 0z runs to come out):

- Most models and runs were showing a moderate strength storm, in the range of Cat 1 or Cat 2 (950 to 980mb).

- GFS really keeps it weak. The 18z never drops it below about 1000mb. Considering GFS tends to really over-deepen systems this year, 16L is a real outlier. That's tropical storm, or even maybe tropical depression strength. Part of this is much more land interaction, but it doesn't deepen the storm at all over the Gulf, which given shear conditions I call GFS as unlikely.

- HMON is the opposite. 905mb monster cat 5. It's also been really over-deepening storms this year, but Carribean and Gulf are both known for rapid intensification, so it can't be thrown out entirely, but I would view this with great suspicion until we see other (non-GFS) models showing similar.

 

Give it until tomorrow mid-day, which will probably be late enough that we'll have a good closed low at or near TS strength for 6-12 hours. Models should do better then!

[NavarreDon]

I'm sure holes can be picked because it's not identical but the 11:00pm FD is eerily similar to Opal which made landfall 22 years ago today in almost the same spot.

Tropical Depression Sixteen Discussion Number   3
NWS National Hurricane Center Miami FL       AL162017
1100 PM EDT Wed Oct 04 2017

There have been some structural changes to the depression during
the past few hours.  Inner-core convection began developing just
after the issuance of the previous advisory, and Colombian radar
images from San Andres are now showing a well-defined convective
band to the east and southeast of the center.  Despite these
changes, Dvorak satellite estimates remain T2.0 from TAFB and SAB,
so the initial intensity is held at 30 kt.

The depression probably only has another 12 hours or so before its
center moves inland over northeastern Nicaragua, but it is still
expected to reach tropical storm strength before that happens.
Once the center re-emerges over the waters of the northwestern
Caribbean Sea a little after 24 hours from now, high oceanic heat
content and low shear should contribute to strengthening.  Despite
these favorable conditions, the amount of strengthening will be
unclear until we know how well the inner core survives crossing over
Nicaragua and Honduras.  Strengthening is likely to continue
through at least day 3 up until the time the cyclone reaches the
central Gulf of Mexico.  After day 3, there are some indications
that higher shear and/or cooler shelf waters over the northern Gulf
of Mexico could lead to some weakening, but that scenario is by no
means a definite one at this time.  Needless to say, there continues
to be greater-than-normal uncertainty in the intensity forecast.
The updated NHC intensity forecast has been adjusted downward just
a bit through day 3 to follow an overall shift in the guidance,
although it should be noted that the official forecast still lies
above the normally skillful HCCA model.

If the intensity forecast is complex, the track forecast is not
much easier.  For the first 48 hours, the models appear split on
how the depression will interact with a disturbance currently
located near the Straits of Florida.  For example, the ECMWF model
shows some interaction with the disturbance's low-level vorticity,
which swings the depression more to the east on the right side of
the guidance envelope.  The GFS, on the other hand, shows no such
interaction and has the cyclone on the western side of the guidance
envelope.  This setup has significant downstream effects after 48
hours because it keeps the ECMWF on an eastern route and the GFS on
a western route as the cyclone heads toward the U.S. Gulf coast.
The new NHC track forecast has been shifted slightly westward,
although it is still not as far west as the consensus aids or the
HCCA model.  Interestingly, although the ECMWF ensemble mean is
close to the operational run on the eastern side of the guidance
envelope, there is a high density of members to the left close to
the consensus aids, which lends additional support for the westward
adjustment.

[40/70 Benchmark]

5 minutes ago, NavarreDon said:

I'm sure holes can be picked because it's not identical but the 11:00pm FD is eerily similar to Opal which made landfall 22 years ago today in almost the same spot.

Tropical Depression Sixteen Discussion Number   3
NWS National Hurricane Center Miami FL       AL162017
1100 PM EDT Wed Oct 04 2017

There have been some structural changes to the depression during
the past few hours.  Inner-core convection began developing just
after the issuance of the previous advisory, and Colombian radar
images from San Andres are now showing a well-defined convective
band to the east and southeast of the center.  Despite these
changes, Dvorak satellite estimates remain T2.0 from TAFB and SAB,
so the initial intensity is held at 30 kt.

The depression probably only has another 12 hours or so before its
center moves inland over northeastern Nicaragua, but it is still
expected to reach tropical storm strength before that happens.
Once the center re-emerges over the waters of the northwestern
Caribbean Sea a little after 24 hours from now, high oceanic heat
content and low shear should contribute to strengthening.  Despite
these favorable conditions, the amount of strengthening will be
unclear until we know how well the inner core survives crossing over
Nicaragua and Honduras.  Strengthening is likely to continue
through at least day 3 up until the time the cyclone reaches the
central Gulf of Mexico.  After day 3, there are some indications
that higher shear and/or cooler shelf waters over the northern Gulf
of Mexico could lead to some weakening, but that scenario is by no
means a definite one at this time.  Needless to say, there continues
to be greater-than-normal uncertainty in the intensity forecast.
The updated NHC intensity forecast has been adjusted downward just
a bit through day 3 to follow an overall shift in the guidance,
although it should be noted that the official forecast still lies
above the normally skillful HCCA model.

If the intensity forecast is complex, the track forecast is not
much easier.  For the first 48 hours, the models appear split on
how the depression will interact with a disturbance currently
located near the Straits of Florida.  For example, the ECMWF model
shows some interaction with the disturbance's low-level vorticity,
which swings the depression more to the east on the right side of
the guidance envelope.  The GFS, on the other hand, shows no such
interaction and has the cyclone on the western side of the guidance
envelope.  This setup has significant downstream effects after 48
hours because it keeps the ECMWF on an eastern route and the GFS on
a western route as the cyclone heads toward the U.S. Gulf coast.
The new NHC track forecast has been shifted slightly westward,
although it is still not as far west as the consensus aids or the
HCCA model.  Interestingly, although the ECMWF ensemble mean is
close to the operational run on the eastern side of the guidance
envelope, there is a high density of members to the left close to
the consensus aids, which lends additional support for the westward
adjustment.

Yea, I made the comparison earlier....likely bombogenesis, then north gulf coast collapse.

[Jim Martin]

Tropical Depression 16 looking disorganized still tonight.

[hawkeye_wx]

GFS with another 'hmmm' run... weak, disorganized, significant land interaction, never does much with it.

[Windspeed]

Tropical Depression 16 looking disorganized still tonight.

 

 

Take a good look. IR can be deceiving. Organization underway. Banding is wrapping into the center of the surface low. I fully expect deep convection to form a core tonight.

 

[Windspeed]

And there it goes...

[Hoosier]

00z UKMET has landfall south of New Orleans by 00z Sunday.

[SeanBarg]

I agree the CDO does seem to be developing quite nicely over the past 2 hours. Quite a differnce seeing the GFS for once not over bombing the system out compared to the Euro.  I understand why, but it's an interesting reversal from what we have seen previously this season. 

[Windspeed]

Another point to add (good or bad) to the good points that have been made so far: Until we have an organized core/vortex, modeling can only simulate a projection of where the intensifying vortex will form. Until we have that vortex, initial land interaction (NE Nicaragua/E. Honduras) cannot be projected accurately nor can secondary interaction (Yucatan) be modeled with better certainty. I think the evolution of said vortex is now underway based on wrapped banding into the surface low and the deep convection that is developing/expanding. The surface low is still a good distance off shore. If the more northern or NNW motion takes over, the initial land interaction may end up being very minimal before a bend in track back to the NW. The progression of what will be Nate is going to be in a very condusive upper level environment for rapid intensification as it traverses the NW Caribbean. We could very well be dealing with a rapidly deepening hurricane near the Riveria Maya and NE Yucatan on Friday.

[Windspeed]

Well well...

[beanskip]

Wow - Euro blinks big time. Major shift west. 

[Windspeed]

The ECMWF op is much more pronounced with the mid-level low that moves west across the GOM ahead of Nate. That feature pulls Nate further west versus previous Euro runs. Score a rarer victory for the GFS this year if this plays out. The Euro still closes off a much more defined vortex in the NW Caribbean versus the 00z GFS. It just doesn't seem to do as much with respect to intensification as with previous runs. Though a modeled borderline hurricane is hardly to be downplayed. It's a global model. Still, the potential for a significant hurricane remains.