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Nate

NavarreDon

By NavarreDon,
in Tropical Headquarters

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NavarreDon

NavarreDon

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And we have NATE! 

BULLETIN
Tropical Storm Nate Intermediate Advisory Number 4A
NWS National Hurricane Center Miami FL       AL162017
800 AM EDT Thu Oct 05 2017

...TROPICAL DEPRESSION BECOMES TROPICAL STORM NATE NEAR THE
COAST OF NICARAGUA...
...FLOODING RAINS EXPECTED OVER PORTIONS OF CENTRAL AMERICA...


SUMMARY OF 800 AM EDT...1200 UTC...INFORMATION
----------------------------------------------
LOCATION...13.9N 83.4W
ABOUT 10 MI...15 KM S OF PUERTO CABEZAS NICARAGUA
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...NW OR 325 DEGREES AT 8 MPH...13 KM/H
MINIMUM CENTRAL PRESSURE...999 MB...29.50 INCHES
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Windspeed

Windspeed

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Nobody is commenting probably because you're thinking this looks like absolute crap, so I guess I'll bite.

 

Yes, Nate looks like absolute crap. A few things of note, the surface low is mostly over land now in NE Nicaragua. It is also still imbedded in the surface trough over Central America. Strong MCS and mesos over and just off the Pacific coast may also be robbing some energy from Nate's western circulation or creating a region of sinking air. Though Nate was upgraded and named this morning, it still doesn't have a well-developed core/vortex. Something I thought was getting under way last night. So here we are...

 

A couple of things to watch for. Even though Nate is still imbedded in the surface trough over central America, the 00z ECMWF still wants to seperate Nate's vortex from it, moving Nate NNW-NW towards the NE Yucatan and the trough west over Southern Mexico. That leaves the door open for a potential hurricane. The GFS refuses to organize Nate much beyond a broader center prior to interaction with the Yucatan. Though it does appear to also seperate the energy that is Nate from the mid-to-surface trough that moves over southern Mexico, but keeps that energy more of an elongated gyre. Nate's circulation inevidably becomes just a part of a surface trough in the western Gulf that moves into LA/Texas and much to do about nothing really. Well besides setting up a really nice moisture feed for some very much needed rain over the Tennessee Valley.

 

I guess I am going to be the homer here. Nate's center should be back out over the NW Caribbean around 06z. It has yet to form an organized core, so I don't even think land interaction is much of an issue. It does need to seperate from that surface trough however. And, of course, can't rule out the possibility of deep convection refocusing/relocating an LLC/vortex east or northeast of the current broader center. I admit I am less confident about a hurricane but things can and do change drastically in as little as 6-12 hours with a system like this. Where/when is a core.. ad nauseam.

 

Edit: Correction, Nate's center should be back our over water by 06z. Sorry about my brain fart there.

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NavarreDon

NavarreDon

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3 minutes ago, Windspeed said:

Nobody commenting probably because you're thinking this looks like absolute crap, so I guess I'll bite.

Yes, Nate looks like crap. A few things of note, the surface low is mostly over land now in NE Nicaragua. It is also still imbedded in the the surface trough over central America. Strong MCS and mesos over and just off the Pacific coast may also be robbing some energy from Nate's western circulation or creating a region of sinking air. Though Nate was upgraded and named this morning, it still doesn't have a well-developed core/vortex. Something I thought was getting under way last night. So here we are...

A couple of things to watch for. Even though Nate is still imbedded in the surface trough over central America, the 00z ECMWF still wants to seperate Nate's vortex from it, moving Nate NNW-NW towards the NE Yucatan and the trough west over Southern Mexico. That leaves the door open for a potential hurricane. The GFS refuses to organize Nate much beyond a broader center prior to interaction with the Yucatan. Though it does appear to also seperate the energy that is Nate from the mid-to-surface trough that moves over southern Mexico, but keeps that energy more of an elongated gyre. Nate's circulation inevidably becomes just a part of a surface trough in the western Gulf that moves into LA/Texas and muh to do about nothing really. Well besides setting up a really nice moisture feed for some very much needed rain over the Tennessee Valley.

I guess I am going to be the homer here. Nate's center should be back out over the NW Caribbean around 21z. It has yet to form an organized core, so I don't even think land interaction is much of an issue. It does need to seperate from that surface trough however. And, of course, can't rule out the possibility of deep convection refocusing/relocating an LLC/vortex east or northeast of the current broader center. I admit I am less confident about a hurricane but things can and do change drastically in as little as 6-12 hours with a system like this. Where/when is a core.. ad nauseam.

What are your thoughts about such a weak unorganized system being modeled? Does anything catch your eye moving this further W or E? Were you surprised by the euro's cave?

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hawkeye_wx

hawkeye_wx

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11 minutes ago, Windspeed said:

Yes, Nate looks like absolute crap. A few things of note, the surface low is mostly over land now in NE Nicaragua. It is also still imbedded in the the surface trough over central America. Strong MCS and mesos over and just off the Pacific coast may also be robbing some energy from Nate's western circulation or creating a region of sinking air. Though Nate was upgraded and named this morning, it still doesn't have a well-developed core/vortex. Something I thought was getting under way last night. So here we are...

I definitely noticed the huge convective blowup off the west coast of Central America overnight.  The cirrus blowoff from all that convection is currently flowing right up over Nate's center.

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hawkeye_wx

hawkeye_wx

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8 minutes ago, WishingForWarmWeather said:

There weren't many folks posting any model runs the past 12 hours. Can anyone give me a little recap of what they're showing? 

The trend has been west toward Louisiana.  The euro had been east, but the 00z run caved.  Models have generally gone weaker as well, with more land interaction and/or a lack of organization.

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hlcater

hlcater

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6 minutes ago, WishingForWarmWeather said:

I don't always ask others, my friend. But I appreciate the feedback. I typically like to leave it to other people to post and analyze because I am not very skilled in that. If you could point me in the direction of where to go to see them, that would be very kind of you. I have a new computer and lost all of my bookmarks. 

Pivotalweather.com, tropcialtidbits.com, weather.us, those are the sites that I use.

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WishingForWarmWeather

WishingForWarmWeather

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Just now, NWLinnCountyIA said:

Pivotalweather.com, tropcialtidbitd.com, weather.us, those are the sites that I use.

Thank you, I've used those last two quite a few times, but never heard of the first. Appreciate it. Isn't there a new site, too, that one of our members forecaster jack made? Do you remember what it is?

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hlcater

hlcater

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2 minutes ago, WishingForWarmWeather said:

Thank you, I've used those last two quite a few times, but never heard of the first. Appreciate it. Isn't there a new site, too, that one of our members forecaster jack made? Do you remember what it is?

Weather.us is his site, it's got free euro. Best part :D

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Windspeed

Windspeed

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What are your thoughts about such a weak unorganized system being modeled? Does anything catch your eye moving this further W or E? Were you surprised by the euro's cave?

 

Not really surprised. The Euro was handling the energy over the Florida Straits/SE Gulf differently. GFS and GEM move that into western Gulf and interacted it w/ Nate's center, gyre, whatever it is at that time. The previous Euro runs were moving that mid-level feature quickly over the Yucatan and squashing it down into the Bay of Campeche. Also the GFS and GEM held stronger ridging over the Southeast CONUS for a longer duration. The ECMWF's previous runs backed 500mb heights further east and south into the Antilles.

 

I'm not a model hugger, but the Euro has seemingly performed better this year. So it was hard not to take notice of its more eastern and stronger solutions with Nate. But this is why we have consensus. Every model caves, even the best ones. Now watch the 12z Euro op shift back east, be more amplified with the longwave trough and trash that mid-level low in the Gulf. Ehh, probably not.

 

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donsutherland1

donsutherland1

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My initial thoughts:

TD 16 strengthened into Nate this morning. Nate will likely make U.S. landfall and probably as a Category 1 hurricane.

Taking into consideration the historic data set for tropical cyclones that formed in the vicinity Nate did, I like the 0z EPS idea more than the GEFS idea. Climatology favors such storms taking a sharper turn to the right toward southwestern Florida. In fact, since 1851, all of the tropical cyclones located within 100 nautical miles of Nate's 11 am position made Florida landfall. 50% of such storms made landfall as Category 1 hurricanes.

However, the synoptic pattern is dramatically different from the composite from the historic data set. In the composite, there is a strong trough over or just off northwestern North America, a strong ridge anchored near central Canada, and a strong trough in northeastern North America. The forecast pattern is almost the complete opposite, with ridges in place of the troughs and a trough in place of the ridge.

Such a pattern would argue against a sharp turn to the right, though a more gradual turn could not be ruled out. Giving some weight to historic climatology the highest risk of landfall would likely lie from the eastern half of the Louisiana coast to the Florida Panhandle (particularly from just southwest of Houma in Louisiana to near Destin in Florida). The 12z ECMWF brings Nate onshore between Golden Meadow and Grand Isle in Louisiana.

Nate10052017.jpg

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Windspeed

Windspeed

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Not buying 998 to 997 from hr 24 to 48 with that track...

 

It's the speed that may be the issue. The upper environment should be okay but Nate has a lead foot. ECMWF essentially has it over water 2-2.5 days from Honduras coast to Gulf coast. It would need to establish a core and bomb. Now that very well may happen but it's unlikely a global model is going to show it in that short amount of time.

 

The HWRF hurricane model, though based on GFS, not ECMWF analysis, does show some decent intensification as Nate pulls north of the Yucatan. So the potential for a stronger hurricane is still there. In conclusion, the 12z consensus has the two major globals at borderline hurricane intensity at landfall and the main tropical model is showing a category 2 in the north-central Gulf.

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jbenedet

jbenedet

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18 minutes ago, Windspeed said:

It's the speed that may be the issue. The upper environment should be okay but Nate has a lead foot. It's essentially 2-2.5 days over water. It would need to establish a core and bomb. Now that very well may happen but it's unlikely a global model is going to show it in that short amount of time.

The HWRF hurricane model, though based on GFS, not ECMWF analysis, does show some decent intensification as Nate pulls north of the Yucatan. So the potential for a stronger hurricane is still there. In conclusion, the 12z consensus has the two major globals at borderline hurricane intensity at landfall and the main tropical model is showing a category 2 in the north-central Gulf.

Disagree with your first paragraph; agree with the second. I'm much more in agreement with the NHC having him as a hurricane at hr hr48 versus 997 mb on the 12z euro...

http://www.nhc.noaa.gov/graphics_at1.shtml?cone#contents

This is a much different setup, but Harvey serves as a good reminder as to how quickly even weak circulations can develop over very warm SST's with favorable atmospheric conditions.  I think 12-24 hrs is plenty of time to see him intensify into a strong TS before passing over/near Cancun...And given the topography of the Yucatán and very short duration of land interaction, I think any weakening will be negligible from 24-48 hrs.

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Windspeed

Windspeed

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Disagree with your first paragraph; agree with the second. I'm much more in agreement with the NHC having him as a hurricane at hr hr48 versus 997 mb on the 12z euro...

 

http://www.nhc.noaa.gov/graphics_at1.shtml?cone#contents

 

This is a much different setup, but Harvey serves as a good reminder as to how quickly even weak circulations can develop over very warm SST's with favorable atmospheric conditions.  I think 12-24 hrs is plenty of time to see him intensify into a strong TS before passing over/near Cancun...And given the topography of the Yucatán and very short duration of land interaction, I think any weakening will be negligible from 24-48 hrs.

 

I'm just trying to explain model reasoning. It wasn't my forecast or call.. ;)

 

I am leaning more towards a Cat 2 at landfall than a Cat 1. But the NHC has to be careful/conservative. We don't even have an organizing TS over water right now in real time, much less a system with a well-defined core/vortex. It is inherently difficult to forecast intensity in such a short amouny of time with regards to structure. I would be reluctant to go with anything stronger than a minimal hurricane in an official forecast right now.

 

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Wannabehippie

Wannabehippie

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1 minute ago, Weatherchaser said:

Nate might look like crap, but he's managing to cause a lot of problems in Central America right now.

https://twitter.com/elnuevodiario/status/916022896430080000

"Nate leaves four dead and at least 9 missing in Nicaragua."

806 people evacuated from the Cayos Miskitos. They found protection in Bilwi.

You don't need a well organized tropical system to cause flooding. Even a tropical depression can do that.

 

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Weatherchaser

Weatherchaser

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2 minutes ago, Wannabehippie said:

You don't need a well organized tropical system to cause flooding. Even a tropical depression can do that.

 

Yep. And I keep thinking about all the areas in Louisiana that continue to have flooding issues. It wouldn't take much to push some areas over the edge

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Windspeed

Windspeed

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Dr. Beven is good to leave the door open for a stronger hurricane with intensity forecast uncertainty:

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.
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Chinook

Chinook

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There is some deep convection in the Pacific, west of Nate's center of circulation, as well as in the Caribbean, about 100mi east of the center of circulation. Years ago I would have wondered how tropical forecasters made sense of messy situations such as this.

RtfQKDW.jpg

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Windspeed

Windspeed

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18z HWRF reaches 961mb Cat 3 in north-central Gulf before weakening to 973 Cat 2 at landfall at 10 PM EDT/9 PM CDT Saturday night. That is a fast moving hurricane. We're literally around 50 hours out based on modeling.

 

Edit: To put that in perspective, if the 18z HWRF is correct, Nate tracks 1,100 miles / 1,770 km in 50 hours at a mean of 22 MPH. But slower initially in gaining N to NW motion tonight, therefore, landfall speed would probably be somewhere around 25 MPH.

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