ATL: NATE - Post Tropical - Discussion

[SoupBone]

Why's it so quiet here?

Lower population area, if it would had been heading towards SE TX or FL it would had been a lot busier, is my explanation

We're also Cat 4/5 fatigued! We shouldn't be, but we are.

[SunnyThoughts]

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000
WTNT41 KNHC 052045
TCDAT1

Tropical Storm Nate Discussion Number 6
NWS National Hurricane Center Miami FL AL162017
500 PM EDT Thu Oct 05 2017

The center of Nate is now over eastern Honduras, and the cloud
pattern has lost some organization since the last advisory due to
passage over land. In addition, recent ASCAT overpasses suggest
that there are no tropical-storm-force winds outside of the coastal
waters of Nicaragua and Honduras. However, surface observations
indicate that the central pressure remains near 1000 mb, and based
on this the initial intensity remains a possibly generous 35 kt.
An Air Force Reserve Hurricane Hunter aircraft is scheduled to
investigate Nate as it emerges from the northern coast of Honduras
around 0300 UTC.

Analyses from CIMSS at the University of Wisconsin suggest that
Nate is currently experiencing about 20 kt of southwesterly vertical
wind shear, which is more than suggested by the SHIPS model. The
large-scale models are in good agreement that this shear should
diminish during the next 12-24 h, leaving Nate in an favorable
environment for strengthening. One change in the models from the
previous advisory is that the GFS now shows more development as Nate
crosses the Gulf of Mexico. The new intensity forecast shows little
change during the first 12 h due to the shear and land interaction,
then it calls for steady intensification though landfall on the
northern Gulf Coast. After landfall, Nate should weaken as it
traverses the eastern United States. It should be noted that while
the forecast shows a peak intensity of 70 kt at 48 h, Nate is
expected to continue to strengthen between 48 h and landfall and
thus is likely to be stronger than 70 kt. It should also be noted
that SHIPS Rapid Intensification Index values remain quite high, and
any period of rapid intensification would lead to Nate being
stronger than currently forecast.

The initial motion is now 330/9. A combination of a large cyclonic
gyre over Central America, a trough of low pressure moving westward
across the Gulf of Mexico, and a building subtropical ridge over
the western Atlantic should steer Nate generally north-northwestward
with an increase in forward speed during the next 48 h or so,
followed by a turn toward the north as the storm reaches the
western end of the ridge. The guidance is in decent agreement on
the direction of motion, but there remains disagreement on the speed
despite a continued trend toward a faster motion. The new forecast
track is similar to the direction of the previous track, but again
shows a faster forward speed that now has the center near the
northeastern Yucatan Peninsula in 24-36 h and near the northern Gulf
Coast in 60-72 h. After the Gulf Coast landfall, Nate or its
remnants are expected to recurve northeastward upon encountering the
mid-latitude westerlies.


KEY MESSAGES:

1. Heavy rainfall is the main threat from Nate in portions of
Central America, with life-threatening flash flooding and mud slides
possible in portions of Nicaragua, Honduras, Costa Rica, Panama, and
Belize through Friday night.

2. Nate is forecast to be near hurricane intensity when it
approaches the Yucatan Peninsula late Friday, bringing direct
impacts from wind, storm surge, and heavy rainfall. A tropical storm
warning and a hurricane watch are in effect for a portion of this
area and life-threatening flash flooding is also possible.

3. Nate is forecast to reach the northern Gulf Coast this weekend as
a hurricane, and the threat of direct impacts from wind, storm
surge, and heavy rainfall is increasing from Louisiana through the
Florida Panhandle. A hurricane watch and storm surge watch will
likely be issued for portions of the northern Gulf Coast tonight or
Friday morning, and residents in these areas should monitor the
progress of Nate and heed any advice given by local officials.


FORECAST POSITIONS AND MAX WINDS

INIT 05/2100Z 14.9N 84.3W 35 KT 40 MPH...INLAND
12H 06/0600Z 16.5N 84.9W 35 KT 40 MPH...OVER WATER
24H 06/1800Z 19.2N 86.1W 45 KT 50 MPH
36H 07/0600Z 22.3N 87.9W 55 KT 65 MPH
48H 07/1800Z 25.6N 89.5W 70 KT 80 MPH
72H 08/1800Z 31.5N 89.5W 50 KT 60 MPH...INLAND
96H 09/1800Z 38.0N 81.5W 25 KT 30 MPH...INLAND
120H 10/1800Z 41.5N 72.0W 20 KT 25 MPH...POST-TROP/INLAND

[crownweather]

Does anyone have the EPS? Both sites I use for it show it blank.

http://wx.graphics/models/tropical/eps_NATE_current.png or

https://www.tropicaltidbits.com/analysis/models/?model=ecmwf-ens&region=atl&pkg=mslpaNorm&runtime=2017100512&fh=0&xpos=0&ypos=0

[stormreader]

Why's it so quiet here?

Lower population area, if it would had been heading towards SE TX or FL it would had been a lot busier, is my explanation

Yeah that and because the models are not enthusiastic about making this into a significant hurricane - maybe we are too used to CAT 4 and CAT 5s that the Atlantic has outputted recently which really are quite rare especially those impacting the mainland.

Regarding movement, Nate should really start to move quickly in the next 24 hours according to the models presumably as it interacts with the trough to the north and has high pressure builds in over Florida/Cuba:

Already see a much more significant forward motion than what we saw the last couple of days. And that should increase as it reaches the top of the Yucatan.

[BiloxiBeachGuy]

Just saw Mike Seidel from The Weather Channel reporting in front of the Biloxi Lighthouse on Beach Boulevard. It's not good when TWC is in town!

[psyclone]

Over the course of 6 forecast cycles, Nate's northern Gulf landfall point has moved nearly 5 degrees longitude westward.

[stormreader]

the upper low is racing to the SW, however

Implications?

if it moves too far to the SW, it will greatly enhance the outflow

I think we may be totally in the dark as far as intensity goes. Once Nate gets back out into the Caribbean (later tonight) we should see solid intensification--strong trop storm (but very easily could be a hurricane over the northern Yucatan). Intensity forecasts have bounced up and down with each model run. I think a forecast for a 90-100 mph storm along the northern gulf coast is not a bad bet. But if it gets any kind of outflow, you could possibly see a 110-115 mph storm along the northern gulf coast. Just anecdotally, October storms can be very intense.

[stormreader]

Over the course of 6 forecast cycles, Nate's northern Gulf landfall point has moved nearly 5 degrees longitude westward.

Yes, the western or GFS solution appears to have been closer to final outcome. We shall see. I really think that tonight's 0z GFS run has more significance (for a change) than the 0Z Euro! GFS appears to have sniffed out this outcome much more effectively than the Euro. Euro is in catch-up phase with Nate. Perhaps, GFS might nudge east some, and get near where the Euro is now (with its very large recent west shift), but we shall see. If GFS hold firm with a central to west La outcome, I think we have to take it very seriously. So far, it has interpreted the atmosphere much better than other models. If it holds firm, I think that's very significant.

[Aric Dunn]

hate to say it.. but the NAM is likely on point with the interaction of the two systems with the 18z run.. track is right in line..

[Steve]

RPM (rapid precision mesoscale model) from weather services international on WDSU Channel 6 has a small tight system hitting between Abbeville and New Iberia in SW LA.

[SoupBone]

Since it's quiet, someone humor me on a hypothetical. He has 50kts of shear right in his path, and I understand he's not supposed to strengthen until he hits the GoM. What's the disruptive potential with 50kts shear (short term)?

[Steve]

GFS 18Z is running. 2mb higher pressure (998 v 996) and a hair East though probably like 5 miles.

Slightly NNE of 12Z and both at 995mb at 18 hours

30 hours 993 both this and last run but a bit farther off the coast in this run.

[CrazyC83]

GFS 18Z is running. 2mb higher pressure (998 v 996) and a hair East though probably like 5 miles.

Slightly NNE of 12Z and both at 995mb at 18 hours

30 hours 993 both this and last run but a bit farther off the coast in this run.

With the wind shear all over the place, I do think that the forecast intensities will start to come down. If it remains very small it might be able to insulate itself, but a more sprawling system would likely be no more than a sheared mess.

[SoupBone]

GFS 18Z is running. 2mb higher pressure (998 v 996) and a hair East though probably like 5 miles.

Slightly NNE of 12Z and both at 995mb at 18 hours

30 hours 993 both this and last run but a bit farther off the coast in this run.

Well that's not good. Graphic?

[CrazyC83]

RPM (rapid precision mesoscale model) from weather services international on WDSU Channel 6 has a small tight system hitting between Abbeville and New Iberia in SW LA.

That would be interesting - and a smaller storm might be able to keep out of the shear easier.

[CrazyC83]

Since it's quiet, someone humor me on a hypothetical. He has 50kts of shear right in his path, and I understand he's not supposed to strengthen until he hits the GoM. What's the disruptive potential with 50kts shear (short term)?

https://i.imgur.com/t1wL3Ts.gif

If it remained 50 kt, Nate would likely dissipate. I still think it is not impossible that such happens...but we'll see.

[Orlando]

Another reason the interest is not as intense for this storm is that it has not been spinning and spinning for days like the Atlantic hurricanes did. With those storms, it took a long time for them to get here, so the drama was intense. Plus they were much stronger early on.

Some of us are still here watching, but like someone said we are just so burned out on hurricanes.

My area has been experiencing high winds from a tropical unnamed wave over the last few days. It has brought rough seas to the central Florida east coast along with flooding in Brevard county. In Orlando, we have had wind gusts of up to 45 mph for several days. Today, it has been rainy off and on and cloudy all day. Temps today in the high 70s.

Keeping an eye on Nate. As I have learned over the past few years, anything can happen with hurricanes. They seem so hard to predict, which is so surprising in today's highly advanced technological atmosphere.

[CrazyC83]

18Z GFS: Slightly to the east and weaker. 991 into south-central LA, probably with winds around 50 kt.

[Steve]

GFS 18Z is running. 2mb higher pressure (998 v 996) and a hair East though probably like 5 miles.

Slightly NNE of 12Z and both at 995mb at 18 hours

30 hours 993 both this and last run but a bit farther off the coast in this run.

With the wind shear all over the place, I do think that the forecast intensities will start to come down. If it remains very small it might be able to insulate itself, but a more sprawling system would likely be no more than a sheared mess.

Hopefully. 997mb vs 995mb last run. Small system slightly NE of 12Z at 54 hours.

[gotabyte]

gotabyte wrote:
Just joined site today.

I live just to the East of New Orleans(Slidell) and I'm having to tell people here what is going on. Most don't seem to pay attention to local news anymore. They think I'm joking when mentioning Hurricane hitting here. I keep getting told "That thing is going to Florida".

Picked up generator gas earlier today and supplies and noticed stores had normal traffic.

We may be without power for a few days from trees falling but with generator and fuel we should be good.


I was just listening to WWL radio, I can't believe how lightly they are taking Nate.

I stopped listening to WWL radio a couple of weeks back. It's hard to explain, but they've gone completely stupid lately.

I agree.