ATL: GERT - Post-Tropical - Discussion

[tolakram]

Looks like SLIDER is stuck on yesterday.

Visible from the Build Your Own page

https://weather.msfc.nasa.gov/cgi-bin/get-abi?satellite=GOESEastconusband02&lat=30&lon=-72&width=1000&height=800&zoom=2&type=Animation&numframes=20&quality=92

[cycloneye]

12z Best track up to 50kts.

AL, 08, 2017081412, , BEST, 0, 299N, 722W, 50, 999, TS

[SouthDadeFish]

Gert is still battling northerly wind shear, but there are signs that the convective structure of the TC has improved this morning, with convection expanding into the upshear quadrants:

[cycloneye]

Tropical Storm Gert Discussion Number 7
NWS National Hurricane Center Miami FL AL082017
1100 AM EDT Mon Aug 14 2017

Gert has become better organized this morning. A recent 1336 UTC
GMI overpass shows a large band of convection wrapping around the
circulation from the southwest to the northwest quadrant. However,
imagery from the GMI overpass, as well as an earlier SSMIS overpass,
suggest that the mid-level center is displaced somewhat south or
southeast of the low-level center, due to continued northerly shear
of about 15 kt. Based on the improved structure and increased
subjective Dvorak classifications from TAFB and SAB, the initial
intensity has been raised to 50 kt.

Gert is now moving toward the north, and the initial motion estimate
is 360/07 kt. Very little change has been made to the track
forecast. Gert should continue to move around the western
periphery of the subtropical ridge for the next day or so, before
rapidly accelerating eastward ahead of a trough. Since Gert has
already turned northward, the NHC forecast is on the eastern side
of the guidance envelope for the first 48 h, but very near the
multi-model consensus after that time.

Despite the presence of moderate northerly vertical wind shear,
there is good agreement among the intensity guidance that Gert will
continue to strengthen for the next 48 h. The HWRF is an outlier
in showing Gert becoming a major hurricane around that time, while
DSHP, LGEM, and CTCI only forecast modest intensification. Since
SHIPS diagnostics from the GFS and ECMWF suggest that the shear will
never decrease below 10 kt, the NHC forecast gives more weight to
the modest intensification scenario. All of the global models show
extratropical transition (ET) beginning around 48 h, and completing
by about 72 h. After ET completes, Gert is still expected to
steadily weaken before being absorbed by a larger extratropical low
in about 4 or 5 days.

The 72 h and 96 h track, intensity, and wind radii forecasts
incorporated guidance from the Ocean Prediction Center.

FORECAST POSITIONS AND MAX WINDS

INIT 14/1500Z 30.3N 72.2W 50 KT 60 MPH
12H 15/0000Z 31.5N 72.2W 55 KT 65 MPH
24H 15/1200Z 33.4N 71.3W 60 KT 70 MPH
36H 16/0000Z 35.8N 68.8W 65 KT 75 MPH
48H 16/1200Z 38.4N 64.0W 70 KT 80 MPH
72H 17/1200Z 43.0N 50.0W 65 KT 75 MPH...POST-TROP/EXTRATROP
96H 18/1200Z 50.0N 36.0W 45 KT 50 MPH...POST-TROP/EXTRATROP
120H 19/1200Z...DISSIPATED

$$
Forecaster Zelinsky

[tolakram]

30 frame visible

https://weather.msfc.nasa.gov/cgi-bin/get-abi?satellite=GOESEastconusband02&lat=30&lon=-72&width=1000&height=800&zoom=2&type=Animation&numframes=30&quality=92

[gatorcane]

looks like maybe another hurricane here. That would make two hurricanes for 2017 so far. Not bad at all and we are just now really ramping up from a climatological perspective.

[EquusStorm]

I've been spoiled by above average seasons, but this is really a rather active year in all but ACE totals for still being early August. Reminds me of 2011.

[gatorcane]

Wow 12Z GFS looks to be showing some really quick deepening. Drops 37MB in 30 hours.

[TheStormExpert]

So the GFS goes from no development to a major hurricane in just 2 days, fascinating!

[Kazmit]

It has "that look". It has some shear to deal with, but I think it's likely that it'll make a run at hurricane strength.

[Alyono]

could see this becoming a cat 2 or a cat 3 as it heads out to sea. Big ACE producer

[RL3AO]

could see this becoming a cat 2 or a cat 3 as it heads out to sea. Big ACE producer

Klotzbachs two week forecast might verify after all. We need 11 ACE in the Aug 4 to 18 period.

[EquusStorm]

NHC has been saying HWRF numbers look like an outlier, but honestly I'm not going to be surprised if it's not all that far off briefly before becoming post-tropical. Small storms in a briefly favorable environment always carry the potential for big surprises.

[RL3AO]

A category 3 might not be out of the question.

[Alyono]

looks like we have an eye. I suspect Gert is a cane now

[tolakram]

SLIDER is working again, beautiful storm, with the eye starting to show up.

http://rammb-slider.cira.colostate.edu/?sat=goes-16&sec=conus&x=8315&y=4983&z=3&im=18&ts=1&st=0&et=0&speed=130&motion=loop&map=1&lat=0&p%5B0%5D=1&opacity%5B0%5D=1&hidden%5B0%5D=0&pause=0&slider=-1&hide_controls=0&mouse_draw=0&s=rammb-slider

[tolakram]

18:07 UTC

[tolakram]

Zoomed out for size reference.

[JaxGator]

Based on recent satellite frames, it appears that an eye and eyewall are starting to form and you can also see the west-east flow of the front that will take it OTS and where it'll most likely be a hurricane causing issues with shipping. The only effects that Gert will have on Florida and the East Coast will be rip currents caused by Gert's swells that are currently hitting the coast.

[tolakram]

Can't stop watching the GOES 16 loop. Gert is putting on a show, safely away from all land. My kind of hurricane. Go Gert.

http://rammb-slider.cira.colostate.edu/?sat=goes-16&sec=conus&x=8096.5&y=5248.5&z=3&im=18&ts=1&st=0&et=0&speed=130&motion=loop&map=1&lat=0&p%5B0%5D=1&opacity%5B0%5D=1&hidden%5B0%5D=0&pause=0&slider=-1&hide_controls=0&mouse_draw=0&s=rammb-slider