EPAC: SEYMOUR - Post-Tropical

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cycloneye
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Re: EPAC: SEYMOUR - Hurricane

#101 Postby cycloneye » Thu Oct 27, 2016 9:57 am

HURRICANE SEYMOUR DISCUSSION NUMBER 18
NWS NATIONAL HURRICANE CENTER MIAMI FL EP202016
800 AM PDT THU OCT 27 2016

Seymour is rapidly weakening due to a combination of southwesterly
vertical wind shear and decreasing sea surface temperatures, with
recent microwave imagery showing the low-level center becoming
exposed to the south of the remaining deep convection. The initial
intensity is lowered to 70 kt based on a blend of satellite
intensity estimates and continuity from the last advisory, and it is
possible this could be generous. Rapid weakening should continue,
and Seymour is forecast to weaken to a tropical storm later today,
become a remnant low in 36 hours or less, and dissipate completely
between 48-72 hours.

The initial motion is 335/10. Seymour is forecast to turn northward
later today, and then north-northeastward tonight or on Friday ahead
of a large deep-layer trough located well offshore of the west coast
of the United States. The track guidance remains tightly clustered
and the new forecast track, which lies near the center of the
guidance envelope, is an update of the previous track.


FORECAST POSITIONS AND MAX WINDS

INIT 27/1500Z 20.2N 122.7W 70 KT 80 MPH
12H 28/0000Z 21.5N 122.7W 55 KT 65 MPH
24H 28/1200Z 23.0N 122.0W 35 KT 40 MPH
36H 29/0000Z 24.3N 120.9W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 29/1200Z 25.6N 120.1W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 30/1200Z...DISSIPATED

$$
Forecaster Beven
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Re: EPAC: SEYMOUR - Tropical Storm

#102 Postby cycloneye » Thu Oct 27, 2016 3:35 pm

TROPICAL STORM SEYMOUR DISCUSSION NUMBER 19
NWS NATIONAL HURRICANE CENTER MIAMI FL EP202016
200 PM PDT THU OCT 27 2016

A combination of cold sea surface temperatures and 35 kt of
southwesterly shear has reduced Seymour to an almost convection-less
swirl of clouds. The initial intensity is reduced to 55 kt based
on a blend of satellite intensity estimates, and this could be
generous. Rapid weakening should continue, and Seymour is forecast
to become a remnant low in 24 hours or less, and dissipate
completely between 48-72 hours.

The initial motion is 345/10. Seymour is forecast to turn northward
during the next several hours, and then northeastward tonight
or on Friday ahead of a large deep-layer trough located well
offshore of the west coast of the United States. The new track
forecast is a little to the left and a little faster than the
previous track, and it remains near the center of the guidance
envelope.


FORECAST POSITIONS AND MAX WINDS

INIT 27/2100Z 21.2N 123.1W 55 KT 65 MPH
12H 28/0600Z 22.6N 122.8W 40 KT 45 MPH
24H 28/1800Z 24.0N 121.7W 30 KT 35 MPH...POST-TROP/REMNT LOW
36H 29/0600Z 25.0N 120.9W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 29/1800Z 26.4N 120.3W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 30/1800Z...DISSIPATED

$$
Forecaster Beven
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Re: EPAC: SEYMOUR - Tropical Storm

#103 Postby cycloneye » Thu Oct 27, 2016 9:35 pm

TROPICAL STORM SEYMOUR DISCUSSION NUMBER 20
NWS NATIONAL HURRICANE CENTER MIAMI FL EP202016
800 PM PDT THU OCT 27 2016

A small area of deep convection has been ongoing more than 100 n mi
north-northeast of Seymour's center during the past few hours, but
it's not really enough to be considered organized. Dvorak Current
Intensity numbers from TAFB and SAB decreased to 3.0/45 kt at 0000
UTC, and more recent ADT estimates are even lower. The advisory
intensity is therefore set at 40 kt. Strong shear and colder
waters ahead of Seymour should continue the fast weakening trend,
and the cyclone is likely to be declared a remnant low in 12 hours
or less due to a lack of organized deep convection. Based on global
model fields, the remnant low is expected to dissipate just after
48 hours.

Seymour has turned northward with an initial motion of 360/9 kt.
As a shallow, convection-less low, Seymour is expected to turn
northeastward ahead of a cold front during the next 24 hours and
then back to the north-northeast by 48 hours. The new NHC track
forecast is nearly identical to the previous advisory during the
first 24 hours, but is then nudged westward at 36 and 48 hours in
line with a general westward shift in the guidance at those times.

FORECAST POSITIONS AND MAX WINDS

INIT 28/0300Z 22.0N 123.0W 40 KT 45 MPH
12H 28/1200Z 23.1N 122.5W 30 KT 35 MPH...POST-TROP/REMNT LOW
24H 29/0000Z 24.2N 121.6W 20 KT 25 MPH...POST-TROP/REMNT LOW
36H 29/1200Z 25.5N 121.1W 15 KT 15 MPH...POST-TROP/REMNT LOW
48H 30/0000Z 27.2N 120.5W 15 KT 15 MPH...POST-TROP/REMNT LOW
72H 31/0000Z...DISSIPATED

$$
Forecaster Berg
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Re: EPAC: SEYMOUR - Tropical Storm

#104 Postby hurricanes1234 » Thu Oct 27, 2016 11:05 pm

Awww. :cry: :cry:

This was a really nice storm to track though. After all, we got a strong late season surprise.
:sun:
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Re: EPAC: SEYMOUR - Tropical Storm

#105 Postby cycloneye » Fri Oct 28, 2016 5:00 am

POST-TROPICAL CYCLONE SEYMOUR DISCUSSION NUMBER 21
NWS NATIONAL HURRICANE CENTER MIAMI FL EP202016
200 AM PDT FRI OCT 28 2016

The cyclone has lacked organized deep convection within 60-100 n mi
of its center for over 12 hours, and no longer qualifies as a
tropical cyclone. Since Seymour has become a post-tropical remnant
low, advisories are being discontinued. Subjective Dvorak
classifications from TAFB and SAB along with scatterometer data
indicated an intensity of near 35 kt at 0600 UTC. Assuming some
additional spindown of the cyclone since then, the advisory
intensity is set at 30 kt. The low will be moving through an
extremely hostile environment of southwesterly shear of 40-45 kt and
SSTs cooler than 23 deg C during the next couple of days. These
environmental factors should cause the remnant low to dissipate in a
couple of days. This is also shown by the global model predictions.

The low has turned toward a slightly east of northward heading, and
the initial motion is about 010/7 kt. A north-northeastward motion,
ahead of an approaching frontal system, is expected over the next
day or so. The official track forecast is adjusted a little to the
left of the previous one, toward the latest model consensus.

For additional information on the remnant low please see High Seas
Forecasts issued by the National Weather Service, under AWIPS
header NFDHSFEPI, WMO header FZPN02 KWBC, and on the web at
http://www.opc.ncep.noaa.gov/shtml/NFDHSFEPI.shtml.

FORECAST POSITIONS AND MAX WINDS

INIT 28/0900Z 22.4N 122.8W 30 KT 35 MPH...POST-TROP/REMNT LOW
12H 28/1800Z 23.3N 122.3W 25 KT 30 MPH...POST-TROP/REMNT LOW
24H 29/0600Z 24.5N 121.7W 20 KT 25 MPH...POST-TROP/REMNT LOW
36H 29/1800Z 25.8N 121.2W 15 KT 15 MPH...POST-TROP/REMNT LOW
48H 30/0600Z 27.5N 121.0W 15 KT 15 MPH...POST-TROP/REMNT LOW
72H 31/0600Z...DISSIPATED

$$
Forecaster Pasch
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