ATL: CHRIS - Post-Tropical

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Re: ATL: CHRIS - Hurricane - Discussion

#441 Postby tolakram » Wed Jul 11, 2018 11:17 am

Image
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Re: ATL: CHRIS - Hurricane - Discussion

#442 Postby TheStormExpert » Wed Jul 11, 2018 11:33 am

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Re: ATL: CHRIS - Hurricane - Discussion

#443 Postby HurricaneEnzo » Wed Jul 11, 2018 11:35 am

tolakram wrote:Image


Quicky started looking better. Maybe it can pull an 04' Hurricane Alex and become a major this far North.
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Re: ATL: CHRIS - Hurricane - Discussion

#444 Postby HurricaneEnzo » Wed Jul 11, 2018 12:16 pm

Props to NHC as well on this one. They had the forecast pretty well nailed down for this storm several days out.
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Re: ATL: CHRIS - Hurricane - Discussion

#445 Postby xtyphooncyclonex » Wed Jul 11, 2018 1:29 pm

Looks better organized

Image
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Re: ATL: CHRIS - Hurricane - Discussion

#446 Postby wxman57 » Wed Jul 11, 2018 1:40 pm

Chris has some nasty spikes in its NW quadrant. Interesting feature.

Image
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Re: ATL: CHRIS - Hurricane - Discussion

#447 Postby Alyono » Wed Jul 11, 2018 3:03 pm

Wondering why CHC is not issuing any tropical storm or hurricane warnings

Have they stopped issuing TC watches and warnings?
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Re: ATL: CHRIS - Advisories

#448 Postby cycloneye » Wed Jul 11, 2018 4:11 pm

Hurricane Chris Discussion Number 21
NWS National Hurricane Center Miami FL AL032018
500 PM AST Wed Jul 11 2018

The eye of Chris has become a little less distinct and more
cloud filled during the past few hours, but the overall cloud
pattern remains quite impressive in satellite imagery. The
respective wind radii were adjusted outward based on a 1454 UTC
ASCAT-A overpass, which included one 65-kt surface wind vector in
the southeastern quadrant. The initial intensity has been lowered
slightly to 80 kt based on a blend of Dvorak intensity estimates of
T4.5/77 from both TAFB and SAB, and an ADT estimate of T5.2/95 kt.

The initial motion estimate is now 050/22 kt. Little change was made
to the previous advisory track. Chris is now embedded within deep
southwesterly flow ahead of a broad trough that is digging
southeastward along the U.S. Northeast and Mid-Atlantic coasts. The
global models are in excellent agreement that the hurricane should
continue to accelerate northeastward for the next 72 hours, passing
over or near southeastern Newfoundland in 24-36 hours as a strong
extratropical cyclone. In contrast to several previous model runs,
the latest NHC guidance shows very little cross-track spread or
speed differences, and is tightly packed about the previous advisory
track. The new forecast track closely follows the previous forecast
and the consensus track models HCCA, TVCN, and FSSE.

During next 6 hours or so, Chris will be passing over a ocean
thermal ridge consisting of SSTs of more than 28 deg C, which is
associated with the Gulf Stream. As a result, little change in
strength is expected during that time. However, by 24 hours and
beyond, the cyclone will be moving over SSTs colder than 12 deg C
and encountering southwesterly vertical wind shear in excess of
30 kt, a detrimental combination that will induce rapid weakening
and also result in transition to an extratropical cyclone. The new
intensity forecast is a little lower than the various intensity
model forecasts to account for stronger shear and colder water.

FORECAST POSITIONS AND MAX WINDS

INIT 11/2100Z 37.8N 65.7W 80 KT 90 MPH
12H 12/0600Z 40.6N 61.9W 75 KT 85 MPH
24H 12/1800Z 44.9N 56.2W 60 KT 70 MPH...POST-TROP/EXTRATROP
36H 13/0600Z 48.8N 49.0W 45 KT 50 MPH...POST-TROP/EXTRATROP
48H 13/1800Z 51.9N 40.0W 35 KT 40 MPH...POST-TROP/EXTRATROP
72H 14/1800Z 58.4N 22.6W 35 KT 40 MPH...POST-TROP/EXTRATROP
96H 15/1800Z 63.0N 14.0W 35 KT 40 MPH...POST-TROP/EXTRATROP
120H 16/1800Z...DISSIPATED

$$
Forecaster Stewart
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Re: ATL: CHRIS - Hurricane - Discussion

#449 Postby Andy_L » Wed Jul 11, 2018 4:21 pm

Alyono wrote:Wondering why CHC is not issuing any tropical storm or hurricane warnings

Have they stopped issuing TC watches and warnings?


Environment Canada have issued wind and rain warnings for parts of newfoundland. Not expected to affect nova Scotia besides higher surf than normal there
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Re: ATL: CHRIS - Hurricane - Discussion

#450 Postby Socalhurcnegirl227 » Wed Jul 11, 2018 5:13 pm

wxman57 wrote:Chris has some nasty spikes in its NW quadrant. Interesting feature.

Image

apparently he wanted to be the punk rock rebel of the group this year and rock a mohawk :lol:
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Re: ATL: CHRIS - Hurricane - Discussion

#451 Postby Alyono » Wed Jul 11, 2018 5:38 pm

Andy_L wrote:
Alyono wrote:Wondering why CHC is not issuing any tropical storm or hurricane warnings

Have they stopped issuing TC watches and warnings?


Environment Canada have issued wind and rain warnings for parts of newfoundland. Not expected to affect nova Scotia besides higher surf than normal there


I know they have those warnings, but I was wondering about why not a TS warning, as they have done previously
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Re: ATL: CHRIS - Hurricane - Discussion

#452 Postby Andy_L » Wed Jul 11, 2018 6:18 pm

Alyono wrote:
Andy_L wrote:
Alyono wrote:Wondering why CHC is not issuing any tropical storm or hurricane warnings

Have they stopped issuing TC watches and warnings?


Environment Canada have issued wind and rain warnings for parts of newfoundland. Not expected to affect nova Scotia besides higher surf than normal there


I know they have those warnings, but I was wondering about why not a TS warning, as they have done previously


Best I could find is the "statement" https://weather.gc.ca/hurricane/statements_e.html

Maybe because it's expected to be post-tropical when it reaches Newfoundland??
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Re: ATL: CHRIS - Hurricane - Discussion

#453 Postby Evil Jeremy » Wed Jul 11, 2018 9:39 pm

The 5pm Public Advisory headline is one of my all-time NHC favorites:

...CHRIS SKEDADDLING NORTHEASTWARD OVER THE OPEN ATLANTIC...

What a word...


EDIT: Stewart, of course.
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Re: ATL: CHRIS - Advisories

#454 Postby cycloneye » Wed Jul 11, 2018 9:52 pm

Hurricane Chris Discussion Number 22
NWS National Hurricane Center Miami FL AL032018
1100 PM AST Wed Jul 11 2018

Chris is quickly unraveling, with its eye completely disintegrating
a few hours ago and the convective pattern showing the hallmarks of
the onset of extratropical transition. Earlier microwave data
actually showed that the hurricane had a concentric eyewall
structure, but the mid-level eye was already being stripped away
from the low-level center due to increasing southwesterly shear.
Chris's initial intensity is set at 75 kt based on a blend of
final T- and CI-numbers from TAFB and SAB.

The hurricane is accelerating toward the northeast with an initial
motion of 050/25 kt, and the acceleration is expected to continue
for the next 48 hours while the cyclone moves ahead of a deep-layer
trough located over eastern Canada. After 48 hours, Chris is
forecast to slow down to the south of Iceland when it interacts
with another deep-layer low. The track guidance is tightly
clustered very close to the previous official forecast during
the first 72 hours, with only a little more model spread and
deviation from the previous forecast at 96 hours. Therefore, the
only change to the updated NHC track forecast is to slow down the
storm a little on day 4 while it's located south of Iceland. Chris
may still exist on day 5, but there's too much uncertainty among
the models to extend the official forecast at this point.

Chris is currently moving over a few warm eddies along the Gulf
Stream, but the hurricane's center will move across the North Wall
within the next 6 hours and head toward much colder waters.
Vertical shear will also be increasing further over the next 24
hours, and Chris is expected to be fully embedded within a frontal
zone within 18-24 hours. The NHC official forecast calls for Chris
to complete extratropical transition just before the center reaches
extreme southeastern Newfoundland within 24 hours, and the cyclone's
intensity should gradually decrease while it moves across the North
Atlantic. The intensity forecast is close to the tropical model
guidance for the first 12-24 hours but then sides closer to the GFS
and ECMWF guidance during the remainder of the forecast.

Chris's wind radii have been adjusted slightly based on a 0034 UTC
ASCAT pass.

FORECAST POSITIONS AND MAX WINDS

INIT 12/0300Z 39.6N 63.0W 75 KT 85 MPH
12H 12/1200Z 42.6N 59.2W 65 KT 75 MPH
24H 13/0000Z 46.9N 52.9W 55 KT 65 MPH...POST-TROP/EXTRATROP
36H 13/1200Z 50.2N 44.8W 45 KT 50 MPH...POST-TROP/EXTRATROP
48H 14/0000Z 53.1N 35.0W 40 KT 45 MPH...POST-TROP/EXTRATROP
72H 15/0000Z 59.6N 21.0W 35 KT 40 MPH...POST-TROP/EXTRATROP
96H 16/0000Z 62.0N 15.0W 30 KT 35 MPH...POST-TROP/EXTRATROP
120H 17/0000Z...DISSIPATED

$$
Forecaster Berg
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Re: ATL: CHRIS - Advisories

#455 Postby Alyono » Thu Jul 12, 2018 4:13 am

Interesting that CHC has this as a 75 kt hurricane while NHC has a 60 kt TS
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Re: ATL: CHRIS - Advisories

#456 Postby cycloneye » Thu Jul 12, 2018 5:22 am

Tropical Storm Chris Discussion Number 23
NWS National Hurricane Center Miami FL AL032018
500 AM AST Thu Jul 12 2018

Deep convection has decreased considerable, and the cloud pattern is
taking the typical shape of cyclones during extratropical transition
with the rain shield expanding toward the northwest quadrant. Only a
small area of thunderstorms remain near the center. Dvorak numbers
from TAFB and SAB are decreasing, and assuming that the cyclone has
weakened since the last ASCAT pass several hours ago, the initial
intensity is set at 60 kt in this advisory. Chris will be moving
over much colder waters, and with the increase in shear, the cyclone
is forecast to acquire extratropical characteristics as it moves
very near the extreme southern portion of Newfoundland later today.
After that time, the post-tropical cyclone should continue toward
the northeast and become absorbed by a larger cyclone in about 3 or
4 days.

Chris is now moving toward the northeast or 045 degrees at 30 kt.
The cyclone is already embedded within the fast mid-latitude
westerlies, and this flow should continue to steer Chris on this
general track until it becomes absorbed. Track models are in
excellent agreement in both direction and speed, increasing
the confidence in the NHC forecast.


FORECAST POSITIONS AND MAX WINDS

INIT 12/0900Z 42.1N 60.1W 60 KT 70 MPH
12H 12/1800Z 45.4N 55.4W 55 KT 65 MPH...POST-TROP/EXTRATROP
24H 13/0600Z 49.0N 48.0W 45 KT 50 MPH...POST-TROP/EXTRATROP
36H 13/1800Z 52.0N 40.0W 40 KT 45 MPH...POST-TROP/EXTRATROP
48H 14/0600Z 54.5N 30.0W 35 KT 40 MPH...POST-TROP/EXTRATROP
72H 15/0600Z 60.0N 20.0W 35 KT 40 MPH...POST-TROP/EXTRATROP
96H 16/0600Z...POST-TROP/EXTRATROP

$$
Forecaster Avila
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Re: ATL: CHRIS - Advisories

#457 Postby Alyono » Thu Jul 12, 2018 6:09 am

from CHC. Their reasoning is more scientifically sound as Dvorak CANNOT be used for systems undergoing ET

FXCN31 CWHX 120600
Tropical cyclone technical information statement issued by the
Canadian Hurricane Centre of Environment Canada at 2.54 AM ADT
Thursday 12 July 2018.

The next statement will be issued by 9.00 AM ADT

1. Current position, strength, central pressure and motion

At 3.00 AM ADT, hurricane Chris was located near latitude 40.8 N and
longitude 61.6 W, about 201 nautical miles or 372 km south-southwest
of Sable Island. Maximum sustained winds are estimated at 75 knots
(139 km/h) and central pressure at 981 MB. Chris is moving northeast
at 27 knots (50 km/h).

2. Forecast position, central pressure and strength

Date time lat lon MSLP Max wind
ADT MB kts kmh
Jul 12 3.00 AM 40.8N 61.6W 981 75 139
Jul 12 9.00 AM 42.6N 59.4W 983 70 130
Jul 12 3.00 PM 44.8N 56.4W 986 60 111 post-tropical
Jul 12 9.00 PM 46.8N 53.2W 989 55 102 post-tropical
Jul 13 3.00 AM 48.7N 49.3W 991 50 93 post-tropical
Jul 13 9.00 AM 50.4N 44.7W 993 45 83 post-tropical
Jul 13 3.00 PM 52.0N 39.6W 994 40 74 post-tropical


3. Technical discussion

A. Analysis

The eye of Chris disappeared around 00Z, and the cloud presentation
has switched to a more spiral pattern with no real sign of an
eyewall, and it is progressively moving into an increasingly sheared
environment. However, it is still near or over a warm core meander in
the gulf stream, with temperatures up to 27 Celsius. There have also
been a couple of new convective bursts. Based on this and the fact
the system is accelerating with ridging to right of track, we are
holding at 75 knots for the intitial intensity.

B. Prognostic

No change to previous track or forecast rationale. Chris is now
embedded in the large scale upper flow and should gradually
accelerate northeastward over the next 24 to 36 hours. It will have
exited the gulf stream at forecast time, and is moving into an
increasingly hostile environment. Extra-tropical transition has
commenced and should be complete before it reaches the Avalon
Peninsula this evening. Most of the track guidance continues to show
the storm brushing the Southern Avalon Peninsula.

C. Predicted wind radii (NM)

Time gales storms hurricane
NE SE SW NW NE SE SW NW NE SE SW NW
12/06Z 115 165 120 80 50 70 50 30 30 35 20 5
12/12Z 115 155 120 75 50 75 50 30 20 30 15 0
12/18Z 100 155 110 70 45 70 45 20 0 0 0 0
13/00Z 95 145 110 55 35 50 50 15 0 0 0 0
13/06Z 80 130 100 45 30 45 45 15 0 0 0 0
13/12Z 70 120 90 40 0 0 0 0 0 0 0 0
13/18Z 70 120 90 40 0 0 0 0 0 0 0 0


END/BORGEL/MERCER
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Re: ATL: CHRIS - Advisories

#458 Postby cycloneye » Thu Jul 12, 2018 10:13 am

Post-Tropical Cyclone Chris Discussion Number 24
NWS National Hurricane Center Miami FL AL032018
1100 AM AST Thu Jul 12 2018

Extratropical transition has been ongoing for the past few hours,
with the rain shield continuing to expand and clouds tops warming in
the northwestern semicircle. In addition, surface observations close
to the center now show a sharp temperature gradient of almost 20 deg
F across the center, which is indicative of the cyclone having
merged with a cold frontal system. As a result, Chris has become a
post-tropical/extratropical cyclone. The intensity of 60 kt is based
on continuity with the previous advisory and earlier ASCAT
scatterometer passes. Gradual weakening is forecast by all of the
intensity model guidance, but the cyclone is still expected to
remain a gale area through 72 hours.

Chris has made a slight westward jog, but the latest model guidance
insists that the cyclone will start moving back toward the northeast
or 045 degrees at 30-31 kt. Post-tropical cyclone Chris is forecast
to remain embedded within the fast mid-latitude westerly flow on the
east side of a broad, deep-layer trough moving eastward over the
northeastern United States and southeastern Canada for the next 48
hours or so. By 72 hours, the cyclone is expected to slow down and
begin moving northward as it interacts with a larger mid-latitude
upper-level low. The NHC model guidance remains tightly packed, so
only minor adjustments to the previous advisory track were required,
and mainly in just the first 12 hours. On the forecast track, the
center of Chris is expected to pass over or near the Avalon
Peninsula of southeastern Newfoundland around 2100-0000 UTC this
afternoon and evening.

This is the last public advisory issued by the National Hurricane
Center on this system. Additional information on this system can be
found in High Seas Forecasts issued by the National Weather Service,
under AWIPS header NFDHSFAT1, WMO header FZNT01 KWBC, and available
on the Web at https://ocean.weather.gov/shtml/NFDHSFAT1.shtml. Other
information on Post-Tropical Cyclone Chris can be found in products
issued by Environment Canada/Canadian Hurricane Centre on the
internet at weather.gc.ca/hurricane/.


FORECAST POSITIONS AND MAX WINDS

INIT 12/1500Z 44.4N 57.7W 60 KT 70 MPH...POST-TROPICAL
12H 13/0000Z 47.7N 52.8W 55 KT 65 MPH...POST-TROP/EXTRATROP
24H 13/1200Z 50.7N 44.7W 45 KT 50 MPH...POST-TROP/EXTRATROP
36H 14/0000Z 53.5N 35.0W 40 KT 45 MPH...POST-TROP/EXTRATROP
48H 14/1200Z 56.5N 26.5W 35 KT 40 MPH...POST-TROP/EXTRATROP
72H 15/1200Z 61.6N 18.9W 35 KT 40 MPH...POST-TROP/EXTRATROP
96H 16/1200Z...DISSIPATED

$$
Forecaster Stewart
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Re: ATL: CHRIS - Post-Tropical

#459 Postby HurricaneRyan » Thu Jul 12, 2018 1:34 pm

Wow this thread died really quick!

Chris was an interesting storm though!
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Re: ATL: CHRIS - Post-Tropical

#460 Postby Kazmit » Thu Jul 12, 2018 2:04 pm

Chris was the earliest second hurricane of a season in 13 years. Only Dennis of 2005 came earlier.
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