EPAC: EIGHT-E - Post-Tropical

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Re: EPAC: EIGHT-E - Tropical Depression

#41 Postby cycloneye » Tue Jul 18, 2017 9:58 pm

Tropical Depression Eight-E Discussion Number 3
NWS National Hurricane Center Miami FL EP082017
800 PM PDT Tue Jul 18 2017

The depression continues to produce small bursts of deep convection,
but microwave data and the last few visible images of the day
indicate that the low-level center is exposed to the northeast of
the thunderstorm activity. Visible imagery also shows a band of
cirrus flowing right over the depression's circulation, indicative
of about 25 kt of west-northwesterly shear. Since Dvorak intensity
estimates have not changed from six hours ago, the initial intensity
is held at 30 kt for this advisory.

The big question mark for both the depression's future track and
intensity is how it will interact with Tropical Storm Greg to its
east. All the global models show the depression swinging to the
southwest and south of Greg during the next several days as the two
circulations interact. The GFS model shows Greg becoming the
dominant cyclone, with the depression eventually dissipating.
However, the ECMWF and Canadian models seem to prefer the depression
becoming the dominant system and absorbing Greg. The UKMET is
somewhere in between, with the two circulations merging. Since Greg
is the stronger of the two systems at this point, we are favoring
that being the dominant one, and the new NHC forecast shows the
depression weakening over time and dissipating by 96 hours.
However, there is a lot of uncertainty in this forecast, and
adjustments would be needed if it becomes apparent that the
depression will end up being the dominant cyclone.

The depression is moving slowly westward with an initial motion of
270/4 kt. Regardless of the cyclone's future intensity, a more
pronounced interaction looks increasingly likely, and the track
guidance has shifted southward on this forecast cycle. As a result,
the updated NHC track forecast has also been shifted south of the
previous forecast, and it lies close to the various consensus aids.
This solution is not, however, quite as far south as the HWRF, GFS,
and HCCA models.

FORECAST POSITIONS AND MAX WINDS

INIT 19/0300Z 14.8N 119.9W 30 KT 35 MPH
12H 19/1200Z 14.6N 120.5W 30 KT 35 MPH
24H 20/0000Z 14.2N 121.2W 25 KT 30 MPH
36H 20/1200Z 13.7N 122.0W 25 KT 30 MPH
48H 21/0000Z 13.2N 122.6W 25 KT 30 MPH
72H 22/0000Z 13.3N 123.5W 25 KT 30 MPH
96H 23/0000Z...DISSIPATED

$$
Forecaster Berg
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Re: EPAC: EIGHT-E - Tropical Depression

#42 Postby Sciencerocks » Wed Jul 19, 2017 2:56 am

Compared to Cindy this thing is quite the beast! :lol:

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Re: EPAC: EIGHT-E - Tropical Depression

#43 Postby cycloneye » Wed Jul 19, 2017 9:43 am

Tropical Depression Eight-E Discussion Number 5
NWS National Hurricane Center Miami FL EP082017
800 AM PDT Wed Jul 19 2017

The center of the depression is challenging to locate this morning
with lots of disorganized convection in the vicinity of the apparent
center. Microwave data suggest it is on the northeast side of the
convective mass, although it doesn't agree that well with the
overnight ASCAT data. The initial position tries to keep continuity
from the overnight advisory, since there was a direct ASCAT hit at
0600Z, but it may have to be revised when visible imagery is
available. The initial wind speed is kept at 30 kt, based on a
blend of the TAFB/SAB fixes.

Unfortunately the forecast of the depression isn't any easier than
locating it. Some binary interaction with the circulation of
Tropical Storm Greg is likely over the next few days since the
cyclones should be moving fairly close to one another. This pattern
would probably steer the depression southwestward, then
northwestward by day 3 as Greg passes to the north and begins to
draw the depression closer to it. The specifics of this
interaction, however, are impossible to determine at this range
because it also depends on how strong and exactly where the two
systems are. It is becoming increasingly likely that Greg will be
the more dominant and stronger system, causing the depression to
take a more southward track, and would potentially absorb the
depression in 4-5 days. The official forecast is shifted southward
in the short-term to account for the latest model guidance, but is
fairly close to the previous forecast at the end of the period.

The intensity forecast is also tricky because many of the global
models suggest that there is a window of lower shear between when
the northwesterly outflow-related shear from Fernanda weakens and
shifts to easterly shear related to the circulation and outflow from
Greg. Most of the guidance, however, does not respond much to the
lower shear, suggesting little change in intensity during the next
couple of days. The new intensity forecast remains close to the
model consensus and the previous NHC prediction, though the cyclone
does have a small chance to become a tropical storm. The majority
of the global models are showing the depression degenerating into a
trough by day 4 due to increasing shear and interaction with the
circulation of Greg, so the NHC forecast follows suit.

It should be noted that this is a very uncertain forecast due to
the unusually high number of difficult-to-predict variables.


FORECAST POSITIONS AND MAX WINDS

INIT 19/1500Z 14.5N 121.1W 30 KT 35 MPH
12H 20/0000Z 14.0N 121.8W 30 KT 35 MPH
24H 20/1200Z 13.3N 122.6W 30 KT 35 MPH
36H 21/0000Z 12.6N 123.3W 30 KT 35 MPH
48H 21/1200Z 12.3N 123.6W 30 KT 35 MPH
72H 22/1200Z 13.0N 124.5W 25 KT 30 MPH
96H 23/1200Z...DISSIPATED

$$
Forecaster Blake
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Re: EPAC: EIGHT-E - Tropical Depression

#44 Postby RL3AO » Wed Jul 19, 2017 2:03 pm

ATCF Best Track
System ID: EP08 (EIGHT)
1200 UTC Jul 19, 2017
Location: 14.6°N, 120.9°W
Central Pressure: 1008 mb
Maximum Winds (1-min): 30 kt (34 mph)
Type: Tropical Depression (TD)

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Re: EPAC: EIGHT-E - Tropical Depression

#45 Postby cycloneye » Wed Jul 19, 2017 3:36 pm

Tropical Depression Eight-E Discussion Number 6
NWS National Hurricane Center Miami FL EP082017
200 PM PDT Wed Jul 19 2017

Visible images confirm that the depression is not very well
organized with limited banding features and a partially exposed
center. ASCAT and satellite classfications suggest that the winds
have dropped to 25 kt, and this will be the initial wind speed.

Cirrus cloud motions show that the northwesterly shear continues to
impinge on the depression. While this shear could abate somewhat
tomorrow, it is likely to quickly resume again by Friday due to
enhanced upper-level outflow from Tropical Storm Greg. Thus little
change in intensity is shown in the new NHC intensity forecast, in
line with the latest guidance, with some weakening expected on
Friday. It would not be surprising if the circulation of the
depression opened up into a trough during the next day or two.

The initial motion of the depression is west-southwest at 5 kt. The
system should move to the southwest or south-southwest around the
circulation of Tropical Storm Greg for the next day or two. Model
guidance has come into better agreement that Greg will be the
dominant cyclone, and the track is shifted southward from the
previous one. By 72 hours, all of the global models open up the
depression into a trough as the weak system gets pulled
northwestward toward Greg.


FORECAST POSITIONS AND MAX WINDS

INIT 19/2100Z 14.1N 121.7W 25 KT 30 MPH
12H 20/0600Z 13.6N 122.3W 25 KT 30 MPH
24H 20/1800Z 12.9N 122.9W 25 KT 30 MPH
36H 21/0600Z 12.3N 123.4W 25 KT 30 MPH
48H 21/1800Z 12.0N 123.5W 20 KT 25 MPH
72H 22/1800Z...DISSIPATED

$$
Forecaster Blake
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Re: EPAC: EIGHT-E - Tropical Depression

#46 Postby Sciencerocks » Thu Jul 20, 2017 3:43 am

000
WTPZ43 KNHC 200836
TCDEP3

Tropical Depression Eight-E Discussion Number 8
NWS National Hurricane Center Miami FL EP082017
200 AM PDT Thu Jul 20 2017

It has been difficult to locate the center this evening, and the
circulation of the depression appears to be limited to a shallow
layer near the surface. The cloud pattern is unchanged and deep
convection remains limited to a single band in the southwestern
quadrant. Satellite intensity estimates remain largely unchanged
since the previous advisory, and the initial intensity is held at
25 kt.

There is no change to the intensity forecast thinking. A combination
of shear from an upper-level low to the north and interaction with
Tropical Storm Greg to the east should prevent the depression from
gaining any organization, causing the system to gradually weaken.
Most of the dynamical guidance suggests that the cyclone will no
longer have a well-defined center within the next 48 hours or so,
and only a slight decrease in convective organization would cause
the system to become a remnant low. A WindSat overpass around
0200 UTC suggested that the circulation was already becoming
elongated, so dissipation could occur sooner than indicated.

The initial motion remains 245/5 kt. The depression is still
expected to be advected generally southwestward, around the
circulation of Tropical Storm Greg. The track models have all
shifted slightly westward, so the NHC track forecast has been
adjusted a little in that direction, but otherwise no significant
changes have been made.

FORECAST POSITIONS AND MAX WINDS

INIT 20/0900Z 13.7N 122.6W 25 KT 30 MPH
12H 20/1800Z 13.2N 123.2W 25 KT 30 MPH
24H 21/0600Z 12.5N 123.9W 25 KT 30 MPH
36H 21/1800Z 12.0N 124.3W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 22/0600Z 11.6N 124.6W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 23/0600Z...DISSIPATED

$$
Forecaster Zelinsky
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Re: EPAC: EIGHT-E - Tropical Depression

#47 Postby cycloneye » Thu Jul 20, 2017 9:54 am

Tropical Depression Eight-E Discussion Number 9
NWS National Hurricane Center Miami FL EP082017
800 AM PDT Thu Jul 20 2017

The center of the depression remains difficult to find, but it
appears to be near a small area of disorganized convection. As
with the previous advisory, the satellite intensity estimates remain
largely unchanged and the initial intensity is held at 25 kt.

There is again no change to the intensity forecast thinking. A
combination of shear from an upper-level low to the north and
interaction with Tropical Storm Greg to the east should cause the
depression to weaken and eventually dissipate. The intensity
forecast has the system degenerating into a remnant low after 24 h
and dissipating after 48 hr as it become absorbed into Greg.
However, the system could decay to a remnant low at any time before
then.

The initial motion remains 245/5 kt. The depression is still
expected to be advected slowly southwestward around the
circulation of Greg until dissipation. The new forecast track is an
update of the previous track.


FORECAST POSITIONS AND MAX WINDS

INIT 20/1500Z 13.4N 123.1W 25 KT 30 MPH
12H 21/0000Z 12.9N 123.8W 25 KT 30 MPH
24H 21/1200Z 12.1N 124.5W 25 KT 30 MPH
36H 22/0000Z 11.6N 125.1W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 22/1200Z 11.6N 125.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 23/1200Z...DISSIPATED

$$
Forecaster Beven
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Re: EPAC: EIGHT-E - Tropical Depression

#48 Postby Sciencerocks » Thu Jul 20, 2017 3:24 pm

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Re: EPAC: EIGHT-E - Post-Tropical

#49 Postby cycloneye » Thu Jul 20, 2017 3:37 pm

Post-Tropical Cyclone Eight-E Discussion Number 10
NWS National Hurricane Center Miami FL EP082017
200 PM PDT Thu Jul 20 2017

Satellite imagery indicates that Tropical Depression Eight-E has
degenerated to a low pressure area in the Intertropical Convergence
Zone, with neither the organized convection nor well-defined
circulation of a tropical cyclone. The remnant low is forecast to
persist for 48 h and then be absorbed by Tropical Storm Greg
passing to the north. While the system will be monitored for signs
of redevelopment, the chance of this occurring appears very low at
the present time.

This is the last advisory issued by the National Hurricane Center
on the system. 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 20/2100Z 13.3N 123.9W 25 KT 30 MPH...POST-TROP/REMNT LOW
12H 21/0600Z 12.7N 124.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
24H 21/1800Z 11.9N 125.3W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 22/0600Z 11.5N 126.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 22/1800Z 11.5N 126.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 23/1800Z...DISSIPATED

$$
Forecaster Beven
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