ATL: NATE - Post Tropical - Discussion

[Alyono]

you'd think that the HWRF would actually be useful this close to landfall. Instead, it has the storm at 1000mb now

[wxman57]

Tides along the Gulf Coast typically range up and down be only 1.5 feet or so. Sunday morning's high tide is only 1 foot above MSL on the Mississippi coast. Not particularly significant. The current prediction is for tides 4 ft above normal there Sunday morning. May be a bit higher, though, particularly east of the point of landfall. Tides between Gulfport & Biloxi may reach 7-8 feet above normal. That's enough to put water over Hwy. 90. Water won't stay long, though. By sunrise, offshore winds should push it all back out to sea.

http://www.nws.noaa.gov/mdl/etsurge/index.php?page=stn&region=gm&datum=msl&list=&map=0-48&type=both&stn=mslous

[latitude_20]

Just north of Tulum in Quintana Roo, MX. Very dense overcast, no breeze and thunderstorms visible to the north. Wondering if winds will pick up here later tonight if Nate undergoes RI.

[GCANE]

WV showing the PV ring effect of what I call secondary ventilation.
Same pattern like Harvey.
Think of it as Nate creating an updraft in the heavy convection.
The air flows out in the upper troposphere and then sinks back to the surface in the subsidence of the PV anomaly.
That surface air then flows back into Nate with moisture being added due to surface heat exchange with the hot water.

Here is the WV image and the corresponding 355K PV.
Note where the orange PV anomaly ring is and compare to the dry air on WV.

Bottom line, this is becoming well ventilated even though there may not be an associated ULL nearby to create an outflow channel.

[NDG]

Fact that the highest winds are well away from the center means its is not well organized.. which is good news.

Recon did not sampled the immediate SE quadrant yet form the LLC, there should be some strong winds there, that's where the buoy reported a 1 min substained close to 60 mph as the COC was passing just to the west of it.

[CrazyC83]

URNT15 KNHC 062302
AF307 0716A NATE HDOB 17 20171006
225230 2216N 08531W 8428 01509 0018 +177 +174 133049 049 033 001 01
225300 2215N 08532W 8430 01505 0017 +179 +172 133049 050 032 000 03
225330 2214N 08532W 8429 01505 0016 +181 +168 131050 051 032 001 03
225400 2212N 08533W 8428 01509 0015 +181 +166 131050 052 034 000 00
225430 2211N 08534W 8433 01502 0013 +183 +162 130050 053 033 002 03
225500 2209N 08534W 8429 01503 0016 +175 +172 126049 051 032 000 01
225530 2208N 08535W 8430 01501 0013 +178 +175 126046 050 033 001 05
225600 2207N 08536W 8435 01498 0012 +180 +173 124046 047 033 001 05
225630 2205N 08537W 8433 01500 0011 +183 +173 126047 047 033 001 00
225700 2204N 08537W 8432 01501 0008 +185 +173 126044 046 035 000 03
225730 2202N 08538W 8430 01500 0006 +186 +169 125043 044 033 001 03
225800 2201N 08539W 8428 01500 0005 +184 +168 121042 043 034 000 03
225830 2200N 08539W 8432 01496 0002 +189 +161 120042 043 035 000 03
225900 2158N 08540W 8426 01499 0002 +184 +172 117043 044 035 001 03
225930 2157N 08541W 8429 01494 9998 +189 +166 116045 045 033 001 00
230000 2155N 08542W 8434 01488 9995 +190 +174 118045 046 035 001 00
230030 2154N 08542W 8425 01497 9996 +187 +176 117047 049 034 001 03
230100 2152N 08543W 8430 01491 9996 +183 +179 112047 049 035 001 05
230130 2151N 08544W 8425 01495 //// +179 //// 108048 051 035 001 01
230200 2149N 08545W 8430 01488 9994 +182 +175 105052 053 035 001 05
$$
;

[GBPackMan]

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.

True BUT warm air does not necessarily mean humid air once you get more than 100-200ft off sea level. Most people focus on 100-200 miles at sea level near the path of the eye/center, so much of their expectations and suggestions are based on ground/sea level observations, which is why many here are expecting and suggesting RI.... Versus the models showing it failing to intensify too much are also looking at med and upper level interactions which can keep the core from warming up too much/too fast, or some mid to high level dry air continually interacting as is common in October storms. This is why they are still suggesting a weak Cat 1 at US landfall.

100 or 200 feet off sea level? I find that statement baffling. the atmosphere is incredibly juiced over the Florida peninsula with Ruskin mentioning 2.2-2.4" PWATS in their earlier discussion. that would be impressive at any point in midsummer let alone early Oct and that air is advecting westward over the Gulf. I have no idea whether Nate will strengthen a good bit before landfall but based on the high octane airmass to the north and the rapidly improving satellite signature this afternoon a good round of intensification may be underway right now. Folks in the hurricane warning area should be expecting a hurricane and hoping for weakening. But as of now it looks like things are steadily escalating.

There are multiple things at play here, I am just explaining multiple dimensions that I've heard and read forecasters talking about that could possibly affect this storm, thus which prevent this from intensifying much beyond a weak Cat 1. You could see a very similar phenomenon with Hurricane Nate of 2011, where these same issues in early Sept. (cooler water temps, dry air) only allowed it to be classified as a Cat 1 hurricane for only 1 day, despite it sitting out over the gulf (Bay of Campeche) for 4+ days. Yes they are different storms and events but similar factors from that one will also affect this one based on circumstances and location. Remember that cooler water could very well be drawn from that same bay into this storm.

Due to the unknown factors, NHC and other forecasters have said it may intensify a bit more than expected primarily to cover their back side in case it does stay outside of the dry air from the dropping jet stream. That is the joy of the unknown, people see something and make suggestions, but ultimately mother nature will do what she wants regardless of our opinions.

https://www.atmos-chem-phys.net/17/10349/2017/
https://en.wikipedia.org/wiki/Hurricane_Nate_(2011)

[Blown Away]

The NHC (OFCL) is the outlier on the high side of the intensity guidance...

[Aric Dunn]

Fact that the highest winds are well away from the center means its is not well organized.. which is good news.

Recon did not sampled the immediate SE quadrant yet form the LLC, there should be some strong winds there.

I'll state again.... the fact the highest winds are well away from the center means there is no inner core and it is not well organized.. vertically not alligned. convection being out run by the LLC ( low level shear....).

recon has sampled plenty to see what is going on..

[NDG]

Maybe a 1 mb drop on the latest pass by the noaa recon plane.

[CrazyC83]

URNT15 KNHC 062312
AF307 0716A NATE HDOB 18 20171006
230230 2148N 08545W 8434 01482 9993 +182 +177 111051 052 036 001 05
230300 2146N 08546W 8425 01491 9992 +185 +171 114052 053 036 001 00
230330 2145N 08547W 8432 01482 9991 +180 +171 113052 053 035 001 03
230400 2143N 08548W 8430 01482 9989 +182 +167 112052 053 035 000 03
230430 2142N 08548W 8428 01484 9988 +177 +174 111052 053 035 001 01
230500 2140N 08549W 8432 01476 9985 +180 +174 110054 055 035 001 03
230530 2139N 08550W 8430 01476 9983 +177 +173 111054 055 034 001 01
230600 2137N 08550W 8429 01476 9981 +179 +170 109051 052 034 002 00
230630 2136N 08551W 8428 01474 9978 +181 +170 109047 050 035 001 00
230700 2134N 08552W 8429 01472 //// +175 //// 109044 045 038 001 01
230730 2133N 08553W 8428 01469 //// +169 //// 108045 046 039 002 05
230800 2131N 08553W 8429 01467 9982 +176 //// 103048 049 033 004 01
230830 2130N 08554W 8431 01463 9982 +171 //// 098049 049 034 004 05
230900 2128N 08555W 8430 01463 9979 +179 //// 097046 049 034 003 01
230930 2127N 08556W 8436 01453 9978 +190 +190 091043 044 029 006 00
231000 2125N 08557W 8422 01466 9974 +190 //// 089041 045 034 006 01
231030 2123N 08557W 8430 01459 9972 +179 //// 082040 044 036 003 01
231100 2122N 08558W 8434 01453 9969 +178 //// 076037 039 034 004 01
231130 2120N 08558W 8428 01455 9965 +188 //// 073036 037 030 005 05
231200 2118N 08558W 8428 01453 9958 +180 //// 070033 037 024 005 05
$$
;

[ScottNAtlanta]

Fact that the highest winds are well away from the center means its is not well organized.. which is good news.

Recon did not sampled the immediate SE quadrant yet form the LLC, there should be some strong winds there.

I'll state again.... the fact the highest winds are well away from the center means there is no inner core and it is not well organized.. vertically not alligned. convection being out run by the LLC ( low level shear....).

recon has sampled plenty to see what is going on..

They have not even made it to the center yet.
Also, the highest winds probably haven't been sampled yet.
I think I'll wait for a center pass before I get all absolutist

[La Breeze]

Are there plans to cancel the watches west of Morgan City?

[Aric Dunn]

Recon did not sampled the immediate SE quadrant yet form the LLC, there should be some strong winds there.

I'll state again.... the fact the highest winds are well away from the center means there is no inner core and it is not well organized.. vertically not alligned. convection being out run by the LLC ( low level shear....).

recon has sampled plenty to see what is going on..

They have not even made it to the center yet.
Also, the highest winds probably haven't been sampled yet.
I think I'll wait for a center pass before I get all absolutist

There has been 2 center passes now from the NOAA plane..

[tropicwatch]

Looking at the noaa recon pass and approaching AF plane, looks like the pressure is falling at a pretty good clip. Also is on the eastern edge of the forecast track again.

[ScottNAtlanta]

I'll state again.... the fact the highest winds are well away from the center means there is no inner core and it is not well organized.. vertically not alligned. convection being out run by the LLC ( low level shear....).

recon has sampled plenty to see what is going on..

They have not even made it to the center yet.
Also, the highest winds probably haven't been sampled yet.
I think I'll wait for a center pass before I get all absolutist

There has been 2 center passes now from the NOAA plane..

Those are some hefty winds near the east side of the center on the last pass on the mission you were talking about (sorry it always throws me off when they say 'non-tasked')
It looks like they are having some problems measuring the pressure as well since they had a couple of 983 reading in there that didnt make sense

[Aric Dunn]

They have not even made it to the center yet.
Also, the highest winds probably haven't been sampled yet.
I think I'll wait for a center pass before I get all absolutist

There has been 2 center passes now from the NOAA plane..

Those are some hefty winds near the east side of the center on the last pass on the mission you were talking about (sorry it always throws me off when they say 'non-tasked')

looking at radar too.. tells the story.. LLC north of the MlC quite a bit.. having stacking issues..

[galaxy401]

Fact that the highest winds are well away from the center means its is not well organized.. which is good news.

Recon did not sampled the immediate SE quadrant yet form the LLC, there should be some strong winds there.

I'll state again.... the fact the highest winds are well away from the center means there is no inner core and it is not well organized.. vertically not alligned. convection being out run by the LLC ( low level shear....).

recon has sampled plenty to see what is going on..

Do you think it will reach hurricane status then?

[CrazyC83]

URNT15 KNHC 062322
AF307 0716A NATE HDOB 19 20171006
231230 2117N 08558W 8437 01444 //// +180 //// 064025 030 029 002 01
231300 2115N 08557W 8428 01448 //// +186 //// 055022 023 028 002 01
231330 2114N 08556W 8431 01442 //// +194 //// 040018 023 031 001 05
231400 2113N 08555W 8433 01434 9928 +199 +197 034014 016 029 000 03
231430 2112N 08553W 8429 01436 9924 +201 +195 033010 012 023 001 00
231500 2111N 08552W 8438 01426 9924 +197 +196 043006 008 023 000 01
231530 2110N 08551W 8428 01434 9921 +198 +193 044006 008 019 001 03
231600 2109N 08549W 8426 01434 9915 +204 +192 043001 004 017 000 00
231630 2108N 08548W 8429 01428 9914 +205 +193 215003 006 017 000 00
231700 2107N 08546W 8429 01430 9913 +206 +193 221006 006 016 001 00
231730 2106N 08545W 8432 01426 9915 +206 +192 227009 010 019 000 03
231800 2104N 08544W 8430 01431 9916 +205 +192 205009 010 017 002 00
231830 2103N 08545W 8428 01434 9915 +207 +193 257011 012 023 001 00
231900 2102N 08546W 8428 01436 9921 +201 +197 270014 016 026 000 00
231930 2100N 08547W 8432 01433 9925 +199 +195 276016 017 024 000 00
232000 2059N 08548W 8429 01439 9925 +204 +182 282016 017 026 000 03
232030 2058N 08549W 8430 01437 9923 +211 +176 279017 017 024 001 03
232100 2056N 08550W 8434 01434 9923 +213 +177 283017 017 022 002 00
232130 2055N 08551W 8426 01445 9927 +210 +178 302020 021 027 001 00
232200 2053N 08551W 8435 01439 9934 +202 +187 288025 028 029 002 03
$$
;

Pressure 991mb (although that may be a tad generous, since the NOAA plae was off a bit too)

[Aric Dunn]

Recon did not sampled the immediate SE quadrant yet form the LLC, there should be some strong winds there.

I'll state again.... the fact the highest winds are well away from the center means there is no inner core and it is not well organized.. vertically not alligned. convection being out run by the LLC ( low level shear....).

recon has sampled plenty to see what is going on..

Do you think it will reach hurricane status then?

quite likely.. just having some issues that likely to prevent it from being too strong... but that does not mean it couldn't..