ATL: NATE - Post Tropical - Discussion

[Dave C]

What maps are you using that show that?

Here's the GFS 200mb https://www.tropicaltidbits.com/analysis/models/?model=gfs&region=atl&pkg=uv200&runtime=2017100612&fh=0&xpos=0&ypos=300

Not seeing this cool air you are talking about as wind direction stays out of the south and southwest at the upper levels.

I am glad you Questioning this person out, He has no idea what is he talking about.

Too many people zoomed in on a tiny area ignoring the outlying factors such as the deeper jet stream, and attributing aspects of a early/mid summer storm in the gulf (which would be suggesting Cat 2 or 3). This is an early winter year with snow already multiple times in the Rockies (compared to typical year of snowfall not being seen until late Oct), which means upper level cooler air, cooler than usual being sucked into this storm. Very simple.
Yet I am the one that has no idea what I'm talking about? How rude.

That same Jetstream will also vent the storm creating an outflow channel.






k

[gatorcane]

To GBPackMan's point, there is some dry air as shown by the GFS that starts to infiltrate into the system once in the GOM (see link below 30 hours). The fact there is also not a well established core and because it is moving so fast do suggest we will not be seeing RI in the Gulf but there is always a chance:

GFS RH values demonstrating the point on the dry air:
https://s1.postimg.org/5oq55g4f0f/gfs_mid_RH_watl_6.png

[GBPackMan]

Judging by current motion it looks like the center would either clip the Yucatan or stay offshore. If that does occur it will continue to deepen as we approach DMAX. May be a rapidly organizing hurricane by morning IMO.

Too much sheer and interaction with other pieces in the region to get much past 80mph winds at landfall.

While the official NHC forecast isn't for it to get to over 80 mph winds, the statement in their last discussion of the storm would seem to debunk your claims:

"Conditions appear favorable for strengthening up to landfall on the
northern Gulf Coast, and Nate is expected to make landfall there as
a hurricane. The new intensity forecast, which is an update of the
previous one, lies near the upper edge of the intensity guidance.
It should be noted that the Rapid Intensification Index of the SHIPS
model continues to indicate an above normal chance of rapid
intensification. However, the current structure of the cyclone does
not favor rapid development."

Note in bold. RI is possible, but NHC isn't forecasting it because of the "current" structure of the storm. Note also, there's nothing about shear or dry air inhibiting RI in this statement. Given the recent favorable changes in structure, why would we NOT expect a higher intensity forecast?

The gyre interaction with the weak low that came off the keys sapping some of the energy as it pushed west and then SW quickly, the remnants of Ramona SW on the the Pacific side sapping some of the energy, plus the speed at which it is moving (21mph+) means the combination of factors will not allow it to intensify much more.
Possible for it to be Cat 2 at landfall? Sure. Possible but very unlikely given the interaction from 4 major aspects impacting the western and central gulf. A bit of rain and a very tiny area of hurricane force winds near what is expected to be the poorly organized eye.

[bella_may]

highest 1 min wind from bouy so far

44.7 kts

currently gusting to 70 mph..

take that back now

4:01 pm 48.6 kts

Hurricane incoming

[NDG]

To GBPackMan's point, there is some dry air as shown by the GFS that starts to infiltrate into the system once in the GOM (see link below 30 hours). The fact there is also not a well established core and because it is moving so fast do suggest we will not be seeing RI in the Gulf but there is always a chance:

GFS RH values demonstrating the point on the dry air:
https://s1.postimg.org/5oq55g4f0f/gfs_mid_RH_watl_6.png

SHIPS does not show Nate having any problems with dry air all the way into landfall, it stay in a very juicy atmosphere.

700-500 MB RH 81 79 77 77 75 65

https://verif.rap.ucar.edu/hurricanes/r ... _ships.txt

[Stormcenter]

Definitely looks to be organizing and strengthening despite it's rapid forward speed.

[bella_may]

Saw someone compare this to the 1916 hurricane that rapidly intensified right before landfall. Similar track https://en.m.wikipedia.org/wiki/1916_Gu ... _hurricane

[Dave C]

Already zipped past that buoy, winds there are now ssw.

[NDG]

Buoy 42056 went from reporting just 6 foot waves to over 18 foot waves in just 4 hours as the COC passed just to the west of it, I am thinking that it is up to at least a 60 mph TS on its way to becoming a hurricane later tonight. IMO.

[CrazyC83]

Already zipped past that buoy, winds there are now ssw.

We could be talking landfall in just over 24 hours at this rate...it's moving at like 25 mph right now.

[Dave C]

Already zipped past that buoy, winds there are now ssw.

We could be talking landfall in just over 24 hours at this rate...it's moving at like 25 mph right now.

Faster motion would mean stronger winds east of landfall.

[txwatcher91]

Too many people zoomed in on a tiny area ignoring the outlying factors such as the deeper jet stream, and attributing aspects of a early/mid summer storm in the gulf (which would be suggesting Cat 2 or 3).

Please take a look at some 850mb temp maps. There is plenty of warm air all across the GOM, Caribbean and even into Texas, New Mexico and Arizona where 850mb temps are anywhere from 15-25C. There is no upper level cool air being sucked into this storm. Period. There's a reason models show this intensifying fairly quickly in the GOM and usually when in a favorable environment as depicted with high RH, low shear and very warm waters you see a storm that deepens very quickly. The Hurricane Center also is the best in the business and they have been constantly mentioning the possibility of RI and the favorable environment.

[Alyono]

cool, dry air is not going to be an issue

The issue will be if the low level winds become more favorable. If the convergence increases, this can intensify quickly. If not, it will struggle

[Aric Dunn]

Already zipped past that buoy, winds there are now ssw.

We could be talking landfall in just over 24 hours at this rate...it's moving at like 25 mph right now.

Faster motion would mean stronger winds east of landfall.

to a certain degree yes it has been shown right front quad has higher winds .. but it is not a 1 to 1 ratio...so just becasue a 75mph hurricane is moving 25 mph does not mean winds are 100 mph..

[txwatcher91]

Based on buoy observations this is probably 990mb and 60mph right now. With 36 hours to go until landfall this has more than enough time to reach more than cat 1 status. Folks, don't let your guard down and if I lived along the LA/MS coast I'd be preparing for a cat 2/3 storm.

[Blown Away]

cool, dry air is not going to be an issue

The issue will be if the low level winds become more favorable. If the convergence increases, this can intensify quickly. If not, it will struggle

Going to be hard to pull all that together moving 20-25 mph IMO...

[CrazyC83]

We could be talking landfall in just over 24 hours at this rate...it's moving at like 25 mph right now.

Faster motion would mean stronger winds east of landfall.

to a certain degree yes it has been shown right front quad has higher winds .. but it is not a 1 to 1 ratio...so just becasue a 75mph hurricane is moving 25 mph does not mean winds are 100 mph..

It would mean the max winds could be hurricane force even if the structure is lousy. Earl 1998 is a similar case. Also the difference between the two sides would be greater.

[Aric Dunn]

Faster motion would mean stronger winds east of landfall.

to a certain degree yes it has been shown right front quad has higher winds .. but it is not a 1 to 1 ratio...so just becasue a 75mph hurricane is moving 25 mph does not mean winds are 100 mph..

It would mean the max winds could be hurricane force even if the structure is lousy. Earl 1998 is a similar case. Also the difference between the two sides would be greater.

yes... was just mentioning it is not a 1 to 1 ratio is all.

[NDG]

Satellite presentation is improving little by little. What sucks is that its been a long time since the last microwave pass over it.

[ronjon]

Nate developing a more circular CDO - once that dry slot mixes out on the NE quad, all systems go for perhaps even rapid intensification - despite the fast forward motion. That ULL to the NW is providing good ventilation to the storm..shear is low.

http://www.ssd.noaa.gov/PS/TROP/floaters/16L/flash-vis-long.html