ATL: HERMINE - Post-Tropical - Discussion

[lilac]

Weather Ry..I'm in West Islip. We're just north of Montauk but didn't come close to flooding for Irene or Sandy so should be ok.

[CrazyC83]

If Hermine goes from tropical to post-tropical and back to tropical, nothing changes in terms of NHC operations?

[Hammy]

I know that the NHC 11pm update says that the wind speed is 50mph, but i have been watching the wind speed maps for the last 2.5 hours, and I haven't seen anything, even offshore, over 37.4.

http://i.imgur.com/NMX3CPM.png

ASCAT shows stronger winds well offshore, as do some ship reports.

[CrazyC83]

I know that the NHC 11pm update says that the wind speed is 50mph, but i have been watching the wind speed maps for the last 2.5 hours, and I haven't seen anything, even offshore, over 37.4.

ASCAT shows stronger winds well offshore.

If that ASCAT pass isn't contradicted by buoys, 55 kt would be the best intensity estimate.

[WilmingtonSandbar]

I know that the NHC 11pm update says that the wind speed is 50mph, but i have been watching the wind speed maps for the last 2.5 hours, and I haven't seen anything, even offshore, over 37.4.

ASCAT shows stronger winds well offshore.

Glad you had the ascat image, because the wind maps I was looking at didn't get that far offshore, and i was reading in the update that they were basing the wind speed off of the offshore numbers. I'm at the tip of the first curve of southern coastline in NC, and the flag at the house next door is hanging slack with no flutter at all right now.

[ncbird]

I know that the NHC 11pm update says that the wind speed is 50mph, but i have been watching the wind speed maps for the last 2.5 hours, and I haven't seen anything, even offshore, over 37.4.

I'm more inland, between Maysville and Trenton. Highest reading I've seen off our home weather station is sustained wind 26mph, gust 43mph. We've had 4.7 in. total rain since noon.

[weathaguyry]

Weather Ry..I'm in West Islip. We're just north of Montauk but didn't come close to flooding for Irene or Sandy so should be ok.

Good to hear, Irene was no problem for us but Sandy was a big problem, I'm crossing my fingers that this won't be bad and that we will have no Sandy 2.0 or anything like that

[ConvergenceZone]

Anyone know when the center suppose to move offshore?

[WilmingtonSandbar]

Anyone know when the center suppose to move offshore?

According to local radar loop, it moved offshore about an hour ago, with just the westernmost part of the center over Wilmington.

[TexasBreeze]

Looks to me that it is decoupling. The mid level center is leaving the lower center behind a bit to the south.

[chaser1]

This will be a bit bizarre to watch Hermine further loose tropical characteristics, then re intensify as baroclinic low... turning tropical? What exactly is that? Not "sub-tropical", not "extra-tropical"... possibly "re-tropical" lol? (how 'bout "tropoclinic" )

[NC George]

I'm more inland, between Maysville and Trenton. Highest reading I've seen off our home weather station is sustained wind 26mph, gust 43mph. We've had 4.7 in. total rain since noon.

I'm in Greenville, NC. We had a real downpour yesterday afternoon from the interaction of the passing front and incoming Hermine, 3" in about 2 hours. It caused local street flooding for an hour or so. Today we've had another 3" so about 6" total in just over 30 hours. Seems to be wrapping up pretty soon here, the wind has picked up a bit, but I'd guess no gusts over around 25. Wind appears to have shifted direction from the E to from the N. Pressure is 995 right now, I saw 994 about 40 minutes ago, so it's probably pulling away from us now.

[Hammy]

Looks like the ASCAT wasn't contradicted by surface obs, they went with 50kt for the 2am advisory.

[Vdogg]

Delete

[Airboy]

Looks to me that the center is around "Pamlico sounds" right now when looking at wind directions from buoys and radar.

Edit: W winds just south of it, sounth wind just east of it.

[cycloneye]

TROPICAL STORM HERMINE DISCUSSION NUMBER 24
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092016
500 AM EDT SAT SEP 03 2016

Satellite, radar and surface observations continue to show that the
circulation of Hermine is elongated with most of the convection well
removed from the area of lowest pressure. It appears that Hermine
has already begun the process of extratropical transition. Based on
earlier satellite-derived winds, the initial intensity remains 50
kt. These winds are occurring over water well removed from the
center in the southeast quadrant.

As indicated in the previous NHC discussion, during the next day or
two, Hermine is expected to undergo a complex interaction with a
mid- to upper-level baroclinic trough that is developing over the
eastern United States. After that time, the dynamical models
forecast the upper trough to cut off directly over the surface
cyclone, and the surface cyclone could regain some tropical cyclone
characteristics, even though it would be under the upper-level low.
By then, the strongest winds are expected to be closer to the
center. Nevertheless, the dynamical guidance forecasts Hermine to
strengthen during this evolution regardless of its final structure,
and the NHC forecast is basically an update of the previous one.
Given the uncertainty in the structure and evolution, the forecast
keeps the cyclone as post-tropical after 24 hours.

The initial motion is difficult to estimate given that Hermine's
circulation is elongated, but cyclone appears to be moving toward
the east-northeast or 060 degrees at 18 kt. The cyclone is forecast
to turn more toward the northeast in about 24 hours, and then turn
northward with a significant decrease in forward speed as
interacts with the upper-level trough, and the steering currents
weaken. After day 4, the cyclone should then move eastward with the
mid-latitude flow. The track forecast is a blend between the
previous NHC one and the multi-model consensus TVCN.


KEY MESSAGES:

1. Hermine is expected to become a post-tropical cyclone while still
producing hazardous winds and storm surge over land. NWS policy
allows NHC to write advisories on and issue tropical storm watches
and warnings for post-tropical cyclones, when the system continues
to pose a significant threat to life and property. NHC and the NWS
Eastern Region have decided that this option will be invoked for
Hermine. After Hermine becomes a post-tropical cyclone, NHC will
continue to issue its full suite of advisory and warning products
for as long as the system remains a significant threat to land.

2. There is still considerable uncertainty as to how many of the
characteristics of a tropical cyclone Hermine will have while it is
off of the coast of the Mid-Atlantic and New England States.
Regardless of its structure, Hermine is expected to be a vigorous
storm with a large wind field that will cause wind, storm surge and
surf hazards along the coast.


FORECAST POSITIONS AND MAX WINDS

INIT 03/0900Z 35.4N 76.5W 50 KT 60 MPH...ON THE COAST
12H 03/1800Z 36.5N 74.2W 50 KT 60 MPH...OVER WATER
24H 04/0600Z 37.3N 72.8W 50 KT 60 MPH...POST-TROPICAL
36H 04/1800Z 38.0N 72.5W 55 KT 65 MPH...POST-TROPICAL
48H 05/0600Z 38.5N 72.3W 60 KT 70 MPH...POST-TROPICAL
72H 06/0600Z 39.0N 72.0W 65 KT 75 MPH...POST-TROPICAL
96H 07/0600Z 39.5N 71.5W 55 KT 65 MPH...POST-TROPICAL
120H 08/0600Z 40.5N 70.0W 45 KT 50 MPH...POST-TROPICAL

$$
Forecaster Avila

[OBXterra]

Location is Southern Shores, NC, half mile inland from beach in Kitty Hawk Woods. Duck research pier reports wind of 67.865 MPH, gusts of 79.35.

http://www.ndbc.noaa.gov/station_page.php?station=dukn7

[weathaguyry]

Here on Long Island, I am going through a mental checklist of what I need, but I'm very surprised they didn't issue a TS Warning yet! Do you guys think they will extend the TS Warning into LI in the 11AM update?

[ncbird]

Gotta give NHC credit. They really nailed the track on this one up the coast so far.

[tolakram]

If an amateur is going to question the NHC they should have all the data the NHC does, otherwise it does a disservice to the readers here trying to get information.

Remember this is more of a hybrid or extra-tropical storm now so the winds will be well removed from the center. If the center can build convection it may return to tropical but this main issue is a nor-easter type of windfield that will spread strong winds well north of any center. Per rules created post-Sandy the NHC is tracking and forecasting this as they would a tropical system.

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