ATL: NATE - Post Tropical - Discussion

[duris]

New Orleans meterologist says "Models over SE LA are discounted b/c they are initializing incorrectly." https://twitter.com/CJohnFranklin/statu ... 5716783105

[caneman]

The NHC has been spot on with their forecast tracks this season and eventual LF should be within 50 miles of their current forecast.

The biggest question mark as always will be intensity. I could see another Category 3 hit if future Nate moves on a NE trajectory. I know Opal has been mentioned several times.

I would disagree with this statement. Error rate would be somewhere between 100 to 300 miles off at 120 hours out. Someone correct me if wrong. Working on memory here which isn't always good

[chaser1]

I don't see a circulation there. Maybe a bit of a spin but definitely not a closed circulation.

I saw this feature last night. Definitely some spin to it but I don't see it really getting vertically stacked. I think this'll be one of those where a mid level vorticity is severely slanted to the north or northeast, and this feature probably destined to be cut down due to strong NE'erly upper level shear once it moves a bit more to the west and into the E. GOM. Boy though, could you imagine if this feature were to stall and/or not really track west into the E. GOM for about 2-3 more days?? Upper level conditions relax significantly in about 60+ hours, so.......??

Right well it does not have to be anything more than a sheared mess to greatly affect soon to be nate.. and that is the point.. now that there is a low level feature pressure are sure to fall which will affect nate..

I suppose, but do you think that a minimal fall in surface pressures would nearly guarantee to reflect enough additional weakness to the mid-levels for T.D. 16 to feel it?

[tropicwatch]

HH's are heading home.

[MGC]

I don't see a circulation with the system approaching Florida Straights, looks like sharp trough. Might have a bit of a circulation trying to form at the mid levels though. Could ramp up quickly if it stays offshore.....MGC

[AFWeather]

The NHC has been spot on with their forecast tracks this season and eventual LF should be within 50 miles of their current forecast.

The biggest question mark as always will be intensity. I could see another Category 3 hit if future Nate moves on a NE trajectory. I know Opal has been mentioned several times.

I would disagree with this statement. Error rate would be somewhere between 100 to 300 miles off at 120 hours out. Someone correct me if wrong. Working on memory here which isn't always good

120 hr error is about 200 nm on average so far this decade. Previous success this year does not guarantee future success with the errors... so yes, I would not bank on landfall being 50 nm on either side of the first forecast track.

http://www.nhc.noaa.gov/verification/pdfs/1989-present_OFCL_ATL_annual_trk_errors.pdf

[Stormcenter]

Initializing what?

New Orleans meterologist says "Models over SE LA are discounted b/c they are initializing incorrectly." https://twitter.com/CJohnFranklin/statu ... 5716783105

[Steve]

Track looks almost identical to Kate in 1985 when in the Gulf.

Maybe landfall wise, but Kate's was a sharp parabolic track vs. a NW/N/NE type movement. I don't disagree with what the European is doing, but I think the NAVGEM/HWRF solutions seem the most realistic from 4/4.5 days out. European is out on its own toward Bay County whereas GFS and HMON seem to be a little far west over to Terrebonnne/St. Mary Parishes, LA. I like east of the LA/MS line for now.

the EC is the most reasonable. It does not have the phantom Ophelia

It doesn't. But the visible satellite has at least something there at the surface now. Spin looks to be just SSE of Miami, FL. http://www.ssd.noaa.gov/goes/east/watl/vis-animated.gif
http://www.ssd.noaa.gov/goes/east/watl/vis-animated.gif

[Ivanhater]

12z Euro ensembles

[duris]

I asked whether he didn't mean the GFS-based over-amplifying the trough per previous Discussion but no response

Initializing what?

New Orleans meterologist says "Models over SE LA are discounted b/c they are initializing incorrectly." https://twitter.com/CJohnFranklin/statu ... 5716783105

[bqknight]

I don't see a circulation with the system approaching Florida Straights, looks like sharp trough. Might have a bit of a circulation trying to form at the mid levels though. Could ramp up quickly if it stays offshore.....MGC

Agreed. I don't see a low level circulation. It looks like it's under some intense shear too.

It has been producing some interesting weather, all the way up in Orlando too. VERY breezy and on and off showers.

[CaneCurious]

I'm from NOLA and I only pay attention to Carl Arredondo on WWL and David Bernard on Fox8.

Initializing what?

New Orleans meterologist says "Models over SE LA are discounted b/c they are initializing incorrectly." https://twitter.com/CJohnFranklin/statu ... 5716783105

[gulf701]

This is the latest discussion by NWS Tallahassee. They are leaning towards the ECMWF.
National Weather Service Tallahassee FL
322 PM EDT Wed Oct 4 2017

LONG TERM [Saturday Through Wednesday]...

Tropical depression 16 has developed in the southwest Caribbean Sea,
and is likely to become a tropical storm, and eventually even a
hurricane as it moves northward across the Gulf of Mexico this
weekend. As mentioned in the "near term" discussion above, we
favor the ECMWF solution, which shows less interaction between
the tropical cyclone and the trough forecast to move west across
FL and the eastern Gulf of Mexico during the next few days. The
GFS and CMC have the tropical cyclone making landfall in LA Sunday
morning, while the 00Z ECMWF ensemble points toward a landfall
somewhere along the northwest FL coast. However, the 12 UTC
operational ECMWF is nearly 24 hours slower, but in roughly the
same landfall point and intensity.

Assuming the cyclone verifies close to the ECMWF ensemble
solutions, conditions across our forecast area will deteriorate
late Saturday and early Sunday, with tropical storm conditions
possible near the coast. Hurricane conditions are possible on
Sunday, but much will depend on how this system develops in size
and intensity. This part of the forecast may (hopefully) become
more clear on Friday as the cyclone traverses the northwest
Caribbean Sea, home to some of the highest oceanic heat content in
the western hemisphere. Unfortunately, if the ECMWF verifies,
this storm will not encounter the strong wind shear and dry air
aloft which tropical cyclones usually experience this time of year
as they approach the northern Gulf Coast. Thus it`s unlikely that
this system will weaken before reaching the coast...wherever that
may be.

[duris]

His response did leave me wondering if he understood initialization: "The GFS based models are over-playing the influence of the trough near the FL straights. Main influence should be developing ridge to east"

I'm from NOLA and I only pay attention to Carl Arredondo on WWL and David Bernard on Fox8.

Initializing what?

New Orleans meterologist says "Models over SE LA are discounted b/c they are initializing incorrectly." https://twitter.com/CJohnFranklin/statu ... 5716783105

[Steve]

I'm from NOLA and I only pay attention to Carl Arredondo on WWL and David Bernard on Fox8.

Initializing what?

New Orleans meterologist says "Models over SE LA are discounted b/c they are initializing incorrectly." https://twitter.com/CJohnFranklin/statu ... 5716783105

Both are decent weathermen. Storm2k is superior to both.

[AFWeather]

His response did leave me wondering if he understood initialization: "The GFS based models are over-playing the influence of the trough near the FL straights. Main influence should be developing ridge to east"

I'm from NOLA and I only pay attention to Carl Arredondo on WWL and David Bernard on Fox8.

Initializing what?

He's trying to explain to the public why the NHC forecast is so far east of the other models he is displaying in his graphic. NHC didn't necessarily say it was an initialization issue, just that the trough is over-amplified. Whether they think that's due to initialization issues, an unrealistic depiction/propagation of the feature in the model forecast, or a mixture of both isn't explicitly stated in the discussion. At my previous job we were part of a conference call NHC did prior to issuing advisory products, so maybe he got additional insight that isn't publicly available. Or, perhaps that's his own conclusion after looking at the given information. There isn't a ton of "truth" in the upper atmosphere (particularly outside the CONUS) to say one way or the other.

[LarryWx]

Maybe landfall wise, but Kate's was a sharp parabolic track vs. a NW/N/NE type movement. I don't disagree with what the European is doing, but I think the NAVGEM/HWRF solutions seem the most realistic from 4/4.5 days out. European is out on its own toward Bay County whereas GFS and HMON seem to be a little far west over to Terrebonnne/St. Mary Parishes, LA. I like east of the LA/MS line for now.

the EC is the most reasonable. It does not have the phantom Ophelia

It doesn't. But the visible satellite has at least something there at the surface now. Spin looks to be just SSE of Miami, FL. http://www.ssd.noaa.gov/goes/east/watl/vis-animated.gif
http://www.ssd.noaa.gov/goes/east/watl/vis-animated.gif

Whether this is (NDG has doubts that it is already down to the surface) or will develop a surface low (like the GFS thinks) or not (like the Euro thinks) will likely have major implications for TD 16. IF this develops a surface circulation, that would seem to mean that the GFS track for TD #16 has a better chance of being closer to reality than the Euro track. Also, with this feature competing for energy with TD 16, I'd think that would mean TD 16 probably doesn't get as strong as it otherwise would have had it been more isolated. Therefore, IF this were to develop a surface low, it could ultimately save the SE US from a potential major H hit from what is now TD 16 though it may mean a place like LA gets hit with whatever TD 16 becomes.

[Steve]

the EC is the most reasonable. It does not have the phantom Ophelia

It doesn't. But the visible satellite has at least something there at the surface now. Spin looks to be just SSE of Miami, FL. http://www.ssd.noaa.gov/goes/east/watl/vis-animated.gif
http://www.ssd.noaa.gov/goes/east/watl/vis-animated.gif

Whether this is (NDG has doubts that it is already down to the surface) or will develop a surface low (like the GFS thinks) or not (like the Euro thinks) will likely have major implications for TD 16. IF this develops a surface circulation, that would seem to mean that the GFS track for TD #16 has a better chance of being closer to reality than the Euro track. Also, with this feature competing for energy with TD 16, I'd think that would mean TD 16 probably doesn't get as strong as it otherwise would have had it been more isolated. Therefore, IF this were to develop a surface low, it could ultimately save the SE US from a potential major H hit from what is now TD 16 though it may mean a place like LA gets hit with whatever TD 16 becomes.

NDG might be right. I haven't looked at the buoy data out there. But if you look at the major providers, there's at least a surface trough there.

Intellicast: http://www.intellicast.com/National/Sur ... rrent.aspx

NOAA: https://www.weather.gov/oun/sfcmaps

Unisys: http://weather.unisys.com/surface/sfc_m ... &region=us

So if the overall center isn't quite at the surface yet, the trough surely is there and should be a continued focusing mechanism as it moves in tandem with the spin. I think you're absolutely correct on the other points. The competition would tend to keep both weaker and obviously the stronger the SFL low gets, the more influence it should have later with Nate.

[wxman57]

I don't buy the much slower ECMWF, and I do think it will be weakening as it nears the coast and is accelerating NE. Lots of uncertainty as far as landfall point, timing, and intensity.

[Stormcenter]

It seems to me as though the NHC is ignoring the trough over the Fl. straits as being a factor on whatever TD #16 does.