ATL: OPHELIA - Extratropical - Discussion

[Dean_175]

NHC finally declared it. We have tropical depression 17.

No Ophelia yet. I wonder why they went with the lower wind estimate when there were gale force winds earlier?

[bob rulz]

Rooting for the ridiculous hurricane streak to continue here, especially since it's no threat to land.

[Vince_and_Grace_fan]

The UKMO and the ICON also much stronger than previousily. The 00Z ICON sent it to SE as a hurricane (well west of the Canary Islands), and the fresh 06Z run is similar (but it extends only for 120 hours, and at 120 hours puts the cyclone a bit norther than the earlier run at the same time).

[supercane4867]

06z GFS has Ophelia alive for over 10 days, which should keeps the ACE going.

[talkon]

Upgraded to TS Ophelia. Now expected to continue the hurricane streak!

000
WTNT42 KNHC 091438
TCDAT2

Tropical Storm Ophelia Discussion Number 2
NWS National Hurricane Center Miami FL AL172017
1100 AM AST Mon Oct 09 2017

The convective pattern of the small cyclone has continued to improve
since the previous advisory, with some thunderstorm activity having
developed near or over the center, along with an increase in curved
banding features in the eastern semicircle. The Dvorak intensity
estimate at 1200Z from TAFB was T2.0/30 kt, but given the
aforementioned improvement in the curved-band structure since that
time, the initial intensity is increased to 35 kt. This makes
Ophelia the fifteenth named storm of the 2017 Atlantic hurricane
season.

The initial motion estimate is 030/04 kt. The steering flow
surrounding Ophelia is expected to continue to be weak for the next
day or so while the cyclone remains entangled with a weak
upper-level low located just to its north and northwest. As a
result, only a slow drift toward the northeast and and east is
forecast. By 36 h, increased mid-level ridging to the northwest of
Ophelia should induce a motion toward the east-southeast and
southeast through 72 h, after which a broad mid-latitude trough is
expected to gradually accelerate the cyclone toward the northeast at
a forward speed of near 10 kt. The official forecast remains down
the middle of the guidance envelope, in close agreement with the
previous forecast track, and the HCCA and TVCX consensus models.
Ophelia should remain far away from land for the next 5 days.

Although Ophelia is forecast to remain over marginally warm SSTs of
26.5-27 deg C, much colder-than-normal temperatures aloft should
offset the relatively cool ocean temperatures and produce sufficient
instability to generate moderate to strong convection for the next
120 h. The GFS-based SHIPS model is currently assessing 25 kt of
westerly vertical wind shear, which obviously isn't occuring based
on the recent development of anticyclonic outflow over the low-level
center and across most of Ophelia's circulation. In contrast, the
UW-CIMSS shear analyses indicate lower shear values near 15 kt.
However, both shear assessments are likely too high given the large
domains that they use to calculate environmental wind shear. Based
on recent trends noted in water vapor imagery showing the shear
decreasing, along with the overall favorable upper-level wind fields
forecast by the GFS and ECMWF, especially after 36 hours, slow but
steady strengthening is expected for the next 5 days, with only
occasional intrusions of dry mid-level air being the primary
inhibiting factor to the intensification process. The official
intensity forecast is close to the NOAA HCCA consensus model, is
about midway between the more aggressive IVCN consensus model that
makes Ophelia a hurricane in about 72 h, and the more conservative
statistical SHIPS and LGEM models. However, even the SHIPS and LGEM
models have increased their peak intensity forecasts by at least 15
kt since the previous advisory.

FORECAST POSITIONS AND MAX WINDS

INIT 09/1500Z 31.4N 39.9W 35 KT 40 MPH
12H 10/0000Z 31.7N 39.5W 40 KT 45 MPH
24H 10/1200Z 31.6N 38.7W 45 KT 50 MPH
36H 11/0000Z 31.3N 38.1W 45 KT 50 MPH
48H 11/1200Z 30.7N 37.7W 50 KT 60 MPH
72H 12/1200Z 29.8N 36.7W 55 KT 65 MPH
96H 13/1200Z 30.5N 34.5W 65 KT 75 MPH
120H 14/1200Z 32.0N 31.0W 65 KT 75 MPH

$$
Forecaster Stewart

[galaxy401]

Is this storm going to behave similar to Nadine? Seems like it's going to meander in the NE Atlantic for awhile.

[Alyono]

could see 10-15 ACE units out of this one

[norva]

If Ophelia can reach hurricane strength, that will be 10 straight! Just wow.

[EquusStorm]

Well, most of the guidance and now the NHC official forecast does indeed make this our tenth straight hurricane. That's just remarkable.

[WeatherGuesser]

Is this storm going to behave similar to Nadine? Seems like it's going to meander in the NE Atlantic for awhile.

I'd be OK with that.

[AutoPenalti]

Is this storm going to behave similar to Nadine? Seems like it's going to meander in the NE Atlantic for awhile.

I'd be OK with that.

Hey, more ACE points for us.

[tolakram]

SLIDER

http://rammb-slider.cira.colostate.edu/?sat=goes-16&sec=full_disk&x=18440.5&y=4703&z=5&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

[CrazyC83]

What are the chances this could become a major hurricane? Has there ever been one that far north and east?

[1900hurricane]

What are the chances this could become a major hurricane? Has there ever been one that far north and east?

Pretty unlikely due to marginal sea surface temperatures. Cold upper level temperatures are helping to offset that (<-60ºC at 200 mb), but not enough for more than a lower end hurricane in my opinion.

[Vince_and_Grace_fan]

The 12Z ICON brings Ophelia very close to Madeira (the wind is at 850 hPa).

[tolakram]

12z GFS

[tolakram]

12Z Euro

[Alyono]

I think a 3 is unlikely, but not impossible.

Alex nearly became a 2 in January when the waters are a good bit colder. This is only going to be over 25C waters through 5-6 days. Alex reached 80 kts over sub 20C waters

[CrazyC83]

It caught my eye that convection is below -80C which is really impressive for the NE Atlantic.

[CrazyC83]

That Euro looks like a fully tropical hurricane into Europe - that would be unprecedented!