ATL: LESLIE - Advisories

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Re: ATL: LESLIE - Advisories

#41 Postby cycloneye » Mon Oct 08, 2018 3:48 pm

Tropical Storm Leslie Discussion Number 50
NWS National Hurricane Center Miami FL AL132018
500 PM AST Mon Oct 08 2018

GOES-16 data indicate that Leslie has a small central dense overcast
with an inner core trying to form on the last few visible images.
Convection has also deepened somewhat, and the overall cloud pattern
is becoming more symmetric. All signs point to strengthening and
the Dvorak estimates are increasing. So for Leslie's 50th
advisory, the wind speed is raised to 50 kt, near the CIMSS ADT
value.

Leslie is moving southeastward at about 12 kt; an unusually fast
pace for this direction. The storm is forecast to slow down
somewhat and turn toward the south-southeast during the next day or
two as the cyclone separates from the mid-latitude flow temporarily
and becomes steered by a mid-level ridge over the central Atlantic.
Fortunately the ridge isn't strong enough for Leslie to move
westward again, and the models all eject Leslie northeastward
because of a deepening trough over the eastern Atlantic. There has
been a notable trend southward through 48 hours, and the official
forecast follows that idea. The forecast becomes a nightmare at
long range, however, with very little agreement on whether Leslie is
accelerated ahead of the trough, like the latest FV3GFS, or gets
left behind again, like the ECMWF. These differences result in a
1200 mile spread of the historically reliable models by day 5,
resulting in a very low confidence forecast. The bulk of the
guidance is now indicating that the "left behind" option is becoming
more likely, but continuity dictates making forecast changes in
smaller chunks. So the official forecast is much slower and farther
south at long range, but is well north of the latest model
consensus. Further southward adjustments could be required if model
trends continue.

Interestingly, model guidance is becoming more certain on Leslie
becoming a hurricane again as it moves over warmer (but still
marginally warm) waters, into a lighter-shear and higher mid-level
humidity enviroment. This makes some sense given that the track is
shifting southward and Leslie should finally move over a warmer
portion of the subtropical Atlantic that it hasn't touched yet. Thus
the intensity forecast is higher than the previous one, and the
corrected-consensus models even suggest category 2 as a peak
intensity is possible. By day 5, increasing shear and cooler waters
should weaken Leslie, and it could be undergoing extratropical
transition at that time.


FORECAST POSITIONS AND MAX WINDS

INIT 08/2100Z 33.8N 45.8W 50 KT 60 MPH
12H 09/0600Z 32.5N 44.4W 55 KT 65 MPH
24H 09/1800Z 30.6N 43.2W 55 KT 65 MPH
36H 10/0600Z 28.9N 42.5W 60 KT 70 MPH
48H 10/1800Z 28.2N 41.7W 65 KT 75 MPH
72H 11/1800Z 29.5N 37.0W 75 KT 85 MPH
96H 12/1800Z 33.5N 26.5W 75 KT 85 MPH
120H 13/1800Z 37.0N 17.0W 60 KT 70 MPH

$$
Forecaster Blake
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Re: ATL: LESLIE - Advisories

#42 Postby cycloneye » Mon Oct 08, 2018 9:41 pm

Tropical Storm Leslie Discussion Number 51
NWS National Hurricane Center Miami FL AL132018
1100 PM AST Mon Oct 08 2018

Satellite and microwave data show that Leslie continues to have a
small central dense overcast, with the latest microwave images
suggesting that Leslie is forming a mid-level eye. Although deep
convection has recently decreased somewhat, all of the 00Z intensity
estimates were 55 kt or higher, so the wind speed is set to that
value.

There is no significant change in initial motion- still
southeastward at about 12 kt. Leslie should slow down and turn
toward the south-southeast during the next day or two as the cyclone
becomes steered by a mid-level ridge over the central Atlantic.
A new trough moves into the eastern Atlantic after that time, which
should eject Leslie generally east-northeastward to the south of the
Azores. Models continue to be in poor agreement on whether that
trough will accelerate Leslie quickly to the northeast at long range
or drop the cyclone to the southwest of Portugal. The recent
GFS-based guidance has generally shifted southward and is slower,
more in line with the 12Z UK/ECMWF models. The new NHC forecast
follows that trend, but is still on the northern side of the
consensus due to continuity concerns, and additional southward
adjustments could be required on later advisories.

Leslie is forecast to move across marginally warm waters within a
moderate shear but a more moist environment over the next few days.
These conditions are likely to support slow strengthening, and
model guidance is in general agreement on this scenario. Only
minor adjustments were made to the previous forecast, and the NHC
forecast remains between the intensity consensus and corrected-
consensus aids. By day 5, increasing shear and cold waters
should weaken Leslie, and it will probably lose convection to
transition into a post-tropical cyclone.


FORECAST POSITIONS AND MAX WINDS

INIT 09/0300Z 32.9N 44.6W 55 KT 65 MPH
12H 09/1200Z 31.5N 43.3W 55 KT 65 MPH
24H 10/0000Z 29.6N 42.5W 60 KT 70 MPH
36H 10/1200Z 28.1N 42.1W 60 KT 70 MPH
48H 11/0000Z 27.9N 41.2W 65 KT 75 MPH
72H 12/0000Z 30.0N 35.5W 75 KT 85 MPH
96H 13/0000Z 33.5N 24.5W 70 KT 80 MPH
120H 14/0000Z 35.5N 16.0W 55 KT 65 MPH...POST-TROPICAL

$$
Forecaster Blake
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Re: ATL: LESLIE - Advisories

#43 Postby cycloneye » Tue Oct 09, 2018 5:12 am

Tropical Storm Leslie Discussion Number 52
NWS National Hurricane Center Miami FL AL132018
500 AM AST Tue Oct 09 2018

Leslie has been steady state overnight. The low-level center is
estimated to be on the southern side of a persistent area of deep
convection. The satellite intensity estimates are largely
unchanged, so the initial intensity is held at 55 kt for this
advisory.

The tropical storm is moving southeastward at 11 kt steered by the
flow on the southwest side of a broad mid- to upper-level trough.
This motion, but a slower pace, is expected during the next 24 to 36
hours as the trough pulls away. After that time, another trough is
expected to dig southward over the north Atlantic, which should
cause Leslie to accelerate east-northeastward. Although the models
are in fair agreement for the next few days, they remain in in poor
agreement on whether or not the trough will continue to carry Leslie
eastward or leave the storm behind around day 5. The GFS and ECMWF
have flip flopped, with the GFS now showing Leslie meandering over
the east Atlantic by day 5 and the ECMWF moving the system eastward
toward Morocco. The ensemble spread remains large in those two
global models and there has not been much run-to-run consistency
either. The NHC track forecast remains near the various consensus
aids, which is usually a good place to be when there is considerable
uncertainty like this.

Leslie should slowly strengthen during the next few days while
it moves over slightly warmer waters and into a more moist
environment. These favorable conditions should allow Leslie to
become a hurricane once again, likely within a day or two.
Weakening is expected to commence this weekend when Leslie is
forecast to move over cooler waters and into an atmosphere of
stronger shear and drier air, and the system is forecast to become
post-tropical by day 5. However, the long range intensity forecast
is strongly linked to where Leslie will be, so since the track
forecast is uncertain, the intensity prediction is likewise.


FORECAST POSITIONS AND MAX WINDS

INIT 09/0900Z 32.2N 43.9W 55 KT 65 MPH
12H 09/1800Z 30.8N 43.1W 55 KT 65 MPH
24H 10/0600Z 29.2N 42.5W 60 KT 70 MPH
36H 10/1800Z 28.1N 42.0W 65 KT 75 MPH
48H 11/0600Z 28.4N 40.5W 65 KT 75 MPH
72H 12/0600Z 31.2N 33.8W 75 KT 85 MPH
96H 13/0600Z 33.5N 23.0W 70 KT 80 MPH
120H 14/0600Z 34.0N 17.0W 55 KT 65 MPH...POST-TROPICAL

$$
Forecaster Cangialosi
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Re: ATL: LESLIE - Advisories

#44 Postby cycloneye » Tue Oct 09, 2018 9:43 am

Tropical Storm Leslie Discussion Number 53
NWS National Hurricane Center Miami FL AL132018
1100 AM AST Tue Oct 09 2018

Recent Dvorak fixes and ASCAT data indicate that Leslie's maximum
winds remain around 55 kt. Although the winds have not yet
increased, the surface center of the tropical storm has become more
embedded within its cold cloud tops and several recent microwave
overpasses indicate that the cyclone is beginning to establish an
inner-core. Strengthening is therefore still expected, and Leslie is
forecast to become a hurricane by tomorrow. The tropical storm is
currently moving south-southeastward at around 11 kt, and the models
are in good agreement that a south-southeastward to southward motion
will continue for the next 24 h or so.

Beginning around 36 h, both the track and intensity forecasts become
very uncertain. In general, most of the global models and their
ensembles indicate that Leslie will begin to accelerate toward the
east-northeast or northeast by Thursday as a mid-latitude trough
approaches from the northwest, however the timing and extent of the
interaction is still highly variable from model to model. Based on
the GFS and ECMWF ensembles, a range of possibilities exists, from
Leslie essentially merging with this trough and becoming
extratropical over the far northeast Atlantic, to Leslie interacting
with the trough very little and continuing to meander over the
central Atlantic. There has been a significant change in the
consensus aids to show a slower track for Leslie based on recent
shifts in the deterministic models, but the NHC track forecast has
not been changed nearly as much, out of respect for continuity and
the high uncertainty in the forecast.

The low confidence in the track forecast beyond 36 h affects the
intensity forecast as well, since it is unclear what environment the
storm will be located within. The intensity forecast is therefore
held near the intensity consensus, and still calls for steady
strengthening during the next several days, followed by weakening by
the end of the forecast period. If Leslie moves as far east as
shown in the NHC track forecast, it would likely become a post-
tropical low by day 5, as shown explicitly in the forecast. However,
until confidence in the track increases, I can't rule out that
Leslie could remain a tropical cyclone almost indefinitely if it
continues meandering over the northern Atlantic.

FORECAST POSITIONS AND MAX WINDS

INIT 09/1500Z 31.3N 43.5W 55 KT 65 MPH
12H 10/0000Z 29.9N 42.9W 55 KT 65 MPH
24H 10/1200Z 28.5N 42.6W 60 KT 70 MPH
36H 11/0000Z 28.1N 41.7W 65 KT 75 MPH
48H 11/1200Z 28.9N 39.5W 70 KT 80 MPH
72H 12/1200Z 32.0N 31.5W 75 KT 85 MPH
96H 13/1200Z 33.5N 22.0W 65 KT 75 MPH
120H 14/1200Z 33.5N 18.0W 50 KT 60 MPH...POST-TROPICAL

$$
Forecaster Zelinsky
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Re: ATL: LESLIE - Advisories

#45 Postby cycloneye » Tue Oct 09, 2018 3:46 pm

Tropical Storm Leslie Discussion Number 54
NWS National Hurricane Center Miami FL AL132018
500 PM AST Tue Oct 09 2018

Leslie's appearance on visible imagery has improved through the
afternoon, and multiple microwave overpasses show the development of
a small mid-level eye. The intensity has been increased to 60 kt
based on an average of the most recent Dvorak classifications from
TAFB and SAB. Leslie is moving over warmer waters and the wind
shear is expected to be low, so additional strengthening is
anticipated and Leslie is forecast to become a hurricane overnight.
Given the relatively favorable environment and the recent
organization of Leslie's inner-core, it is possible that Leslie
could intensify a little faster than currently indicated by the NHC
forecast. Beyond day 2, there is particularly low confidence in the
intensity forecast since the track of Leslie is highly uncertain,
and the NHC forecast essentially follows the intensity consensus. It
is likely that the farther south and west Leslie remains, the
stronger it will be.

Unfortunately the track forecast has not become any clearer.
Recent GFS and ECMWF ensemble forecasts still indicate that a range
of possibilities exist, from Leslie becoming extratropical and
heading toward the extreme northeast Atlantic, to Leslie turning
back west in a few days and persisting as a tropical cyclone. No
large changes were made to the track forecast at this time, since I
see no reason to commit to a new solution at this time. The NHC
forecast is close to HCCA at all forecast hours, but confidence is
low to say the least.


FORECAST POSITIONS AND MAX WINDS

INIT 09/2100Z 30.3N 43.0W 60 KT 70 MPH
12H 10/0600Z 29.0N 42.6W 65 KT 75 MPH
24H 10/1800Z 28.0N 42.2W 70 KT 80 MPH
36H 11/0600Z 28.1N 41.4W 75 KT 85 MPH
48H 11/1800Z 29.2N 38.9W 75 KT 85 MPH
72H 12/1800Z 32.0N 29.5W 75 KT 85 MPH
96H 13/1800Z 33.0N 22.0W 60 KT 70 MPH
120H 14/1800Z 31.0N 20.0W 45 KT 50 MPH

$$
Forecaster Zelinsky
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Re: ATL: LESLIE - Advisories

#46 Postby cycloneye » Tue Oct 09, 2018 9:44 pm

BULLETIN
Hurricane Leslie Advisory Number 55
NWS National Hurricane Center Miami FL AL132018
1100 PM AST Tue Oct 09 2018

...EVERLASTING LESLIE BECOMES A HURRICANE AGAIN...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...29.5N 42.6W
ABOUT 1070 MI...1720 KM WSW OF THE AZORES
MAXIMUM SUSTAINED WINDS...75 MPH...120 KM/H
PRESENT MOVEMENT...SSE OR 160 DEGREES AT 9 MPH...15 KM/H
MINIMUM CENTRAL PRESSURE...981 MB...28.97 INCHES



Hurricane Leslie Discussion Number 55
NWS National Hurricane Center Miami FL AL132018
1100 PM AST Tue Oct 09 2018

Satellite and microwave data indicate that Leslie has become a
hurricane again, almost exactly a week after it did the first time.
A WindSat pass from earlier today showed the development of an eye
feature, and with the Dvorak estimates from TAFB and SAB at
hurricane strength, the initial wind speed is set to 65 kt. The
latest GOES-16 proxy visible imagery suggests that a ragged eye has
formed, although the eyewall is open on the southwestern side.

Leslie is atypically intensifying while moving south-southeastward
at 8 kt. The hurricane should continue to lose latitude for a day
or so then get accelerated east-northeastward by a mid-latitude
trough until Friday. After that time, there is a ginormous spread
in the model ensembles with Leslie's final destination ranging from
Ireland all the way to missing the trough and turning around to the
southwest due to a building eastern Atlantic subtropical ridge.
Compared to 12 hours ago, more of the ensemble members are showing
Leslie getting left behind, which is also reflected in the latest
deterministic runs as well. Something tells me that Leslie has at
least one more trick up its sleeve, so the official forecast shows
this trend, but is very low confidence.

With fairly low shear and marginally warm waters for the next day
or two, there is no reason to expect that Leslie won't continue to
intensify. Model guidance is higher than the last cycle, with the
normally conservative ECMWF and GFS models even suggesting that
Leslie becomes a category 2 hurricane in a couple of days. Most of
the rest of the guidance is lower than those models, but the
intensity forecast is shaded in the direction of the ECMWF/GFS,
and is higher than the last NHC prediction. After that time, an
increase in shear and lower SSTs should cause Leslie to weaken. It
is even possible it will become a post-tropical cyclone by day 5,
but I'm not going to show that at this time since I was too
premature last night in this transition.


FORECAST POSITIONS AND MAX WINDS

INIT 10/0300Z 29.5N 42.6W 65 KT 75 MPH
12H 10/1200Z 28.4N 42.3W 70 KT 80 MPH
24H 11/0000Z 28.0N 41.6W 75 KT 85 MPH
36H 11/1200Z 28.6N 39.8W 80 KT 90 MPH
48H 12/0000Z 29.9N 36.4W 80 KT 90 MPH
72H 13/0000Z 32.2N 27.0W 75 KT 85 MPH
96H 14/0000Z 32.0N 21.0W 55 KT 65 MPH
120H 15/0000Z 30.0N 22.0W 40 KT 45 MPH

$$
Forecaster Blake
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Re: ATL: LESLIE - Advisories

#47 Postby cycloneye » Wed Oct 10, 2018 5:00 am

Hurricane Leslie Discussion Number 56
NWS National Hurricane Center Miami FL AL132018
500 AM AST Wed Oct 10 2018

Geostationary satellite and microwave images indicate that Leslie
has a large and ragged banded eye feature with deep convection most
organized over the northern semicircle. Since the Dvorak
classifications from TAFB and SAB are unchanged at 4.0/65 kt, the
initial wind speed is held at that value. Leslie has another day or
two to strengthen while it remains in low wind shear conditions and
over marginally warm waters. After that time, an increase in shear
and lower SSTs should cause Leslie to weaken. It is possible that
Leslie could become a post-tropical cyclone by day 5, but confidence
is not high on that occurring. The NHC intensity forecast is
largely an update of the previous one and it lies at the high end of
the model guidance.

Leslie is now moving southward at 9 kt in the flow on the southwest
side of a broad mid- to upper-level trough. A slower south-
southeastward motion is expected during the day today as the
trough pulls away. A turn to the east-northeast is expected tonight
as another trough approaches Leslie from the northwest, and that
motion with an increase in forward speed is expected through early
this weekend. After that time, the models are coming into better
agreement in showing Leslie being left behind and moving
southwestward on Sunday and Monday as a ridge builds to its
northwest. The NHC track forecast is adjusted southward at days 3
to 5 to be closer to the latest consensus aids. Although the
deterministic models are in better agreement this cycle, there is
still a lot of spread in the GFS and ECMWF ensemble members and
confidence in the track forecast remains fairly low.

FORECAST POSITIONS AND MAX WINDS

INIT 10/0900Z 28.6N 42.6W 65 KT 75 MPH
12H 10/1800Z 28.0N 42.3W 70 KT 80 MPH
24H 11/0600Z 28.1N 40.9W 75 KT 85 MPH
36H 11/1800Z 29.1N 38.3W 80 KT 90 MPH
48H 12/0600Z 30.5N 34.2W 75 KT 85 MPH
72H 13/0600Z 31.5N 25.0W 70 KT 80 MPH
96H 14/0600Z 30.5N 21.5W 50 KT 60 MPH
120H 15/0600Z 28.5N 23.5W 40 KT 45 MPH

$$
Forecaster Cangialosi
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Re: ATL: LESLIE - Advisories

#48 Postby cycloneye » Wed Oct 10, 2018 9:48 am

Hurricane Leslie Discussion Number 57
NWS National Hurricane Center Miami FL AL132018
1100 AM AST Wed Oct 10 2018

Leslie has continued to get better organized this morning, and
several recent microwave overpasses indicate that the hurricane is
maintaining a well-defined mid-level eye. However, objective and
subjective intensity estimates have not increased, so the intensity
has been held at 65 kt. All of the intensity guidance forecasts
that Leslie will resume intensifying later today. Given that the
hurricane is located in a low shear environment and crossing over
the warmest waters it has encountered in days, this seems very
likely. No change was made to the intensity forecast through 48 h.
Beyond that time, the intensity forecast is still tied to the track
forecast, and the farther south and west Leslie remains, the
stronger it will likely be. Extratropical transition also can not
be ruled out, which would likely result in a higher intensity by day
5 that indicated by the NHC forecast. The official intensity
forecast is still close to the model consensus through day 5, but a
large range of possibilities exists by that time, from Leslie
becoming a weak post-tropical low, to maintaining near hurricane
strength.

The spread in the track guidance is still very large and confidence
in the track forecast is low. The most recent ECMWF ensemble has a
5-day spread of over 1500 n mi, while the 5-day GFS ensemble spread
is over 1300 n mi. Leslie is forecast to slow down today and turn
toward the east-northeast. A faster motion in that direction is
anticipated by tomorrow as a mid-latitude trough approaches from
the northwest. Leslie will then either undergo extratropical
transition and lift northward, continue westward and become a
remnant low, or separate from the trough and turn back west. The
NHC forecast is near the track consensus at all times and no large
changes to the forecast were made since the future track of the
cyclone has not become more clear.

FORECAST POSITIONS AND MAX WINDS

INIT 10/1500Z 27.8N 42.3W 65 KT 75 MPH
12H 11/0000Z 27.8N 41.6W 70 KT 80 MPH
24H 11/1200Z 28.4N 39.7W 75 KT 85 MPH
36H 12/0000Z 29.6N 36.2W 80 KT 90 MPH
48H 12/1200Z 30.7N 31.8W 75 KT 85 MPH
72H 13/1200Z 31.5N 23.0W 60 KT 70 MPH
96H 14/1200Z 29.5N 22.0W 40 KT 45 MPH
120H 15/1200Z 27.0N 26.0W 35 KT 40 MPH

$$
Forecaster Zelinsky
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Re: ATL: LESLIE - Advisories

#49 Postby cycloneye » Wed Oct 10, 2018 3:47 pm

Hurricane Leslie Discussion Number 58
NWS National Hurricane Center Miami FL AL132018
500 PM AST Wed Oct 10 2018

Leslie has held nearly steady since this morning. Recent microwave
data indicate that the cyclone still has a fairly well-defined
inner-core that has persisted, though the deepest convection has
fluctuated since last night. Satellite intensity estimates have
fluctuated with the convection, but still support an initial value
of 65 kt for this advisory. The last few IR and visible images
before sunset suggest that Leslie may be developing a banding eye,
and it's possible the intensity estimate is a little conservative.

The track uncertainty is hopefully beginning to decrease a little.
The most recent GFS and ECMWF ensembles are converging on a solution
where Leslie accelerates east-northeastward on the south side of a
mid-latitude trough, before separating from the trough over the
weekend. The cyclone could then turn southward, and eventually back
westward as a much weaker tropical cyclone or remnant low. This is
generally consistent with previous NHC forecasts, so no large
changes were required to the NHC forecast which is heavily based on
the HFIP Corrected Consensus.

Leslie is still expected to strengthen soon, and there has been no
significant change to the intensity forecast. By 72 h, if not
sooner, the hurricane will begin to encounter colder ocean waters
and high shear, which should cause it to weaken. If Leslie follows
the forecast track, it is possible that the system could become a
post-tropical remnant low by early next week, and this is forecast
by some of the global models. However, this is not explicitly shown
in the NHC forecast and Leslie's strength and status early next week
will likely heavily depend on its track at that time. The official
forecast is close to the intensity consensus at all forecast hours,
and the intensity model spread is not very large.


FORECAST POSITIONS AND MAX WINDS

INIT 10/2100Z 27.8N 41.9W 65 KT 75 MPH
12H 11/0600Z 28.0N 40.8W 70 KT 80 MPH
24H 11/1800Z 29.0N 38.0W 75 KT 85 MPH
36H 12/0600Z 30.4N 33.6W 75 KT 85 MPH
48H 12/1800Z 31.5N 28.4W 70 KT 80 MPH
72H 13/1800Z 32.0N 21.0W 50 KT 60 MPH
96H 14/1800Z 30.0N 21.0W 35 KT 40 MPH
120H 15/1800Z 27.0N 26.0W 30 KT 35 MPH

$$
Forecaster Zelinsky
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Re: ATL: LESLIE - Advisories

#50 Postby cycloneye » Wed Oct 10, 2018 9:50 pm

Hurricane Leslie Discussion Number 59
NWS National Hurricane Center Miami FL AL132018
1100 PM AST Wed Oct 10 2018

The overall cloud pattern of Leslie has become somewhat better
organized over the past several hours with increasing convection
in the central dense overcast and tighter banding features. A blend
of the subjective Dvorak and microwave estimates suggest an initial
wind speed of 70 kt for this advisory.

Satellite fixes indicate that Leslie has turned toward the east-
northeast and is moving faster at about 10 kt. The track forecast
really hinges on whether Leslie gets accelerated in southwesterly
flow ahead of an eastern Atlantic trough or gets dropped by that
trough and turns southwestward around a new subtropical ridge.
Sadly, the forecast agreement from the previous advisory has
disintegrated, with all of the GFS-based guidance now indicating a
track more toward Europe, while the ECMWF/UKMET send Leslie in the
exact opposite direction toward the east-central Atlantic. I
clearly drew the small straw in having to make Leslie's forecast
tonight because this situation is resulting in one of the largest
guidance spreads I have seen, about 1000 miles on day 3 and over
2000 miles at day 5. Furthermore, the corrected-consensus guidance
is closer to the GFS guidance, which is way to the northeast of the
previous forecast. The new forecast will somewhat reflect the
latest guidance, showing an adjustment to the east, but is still
hundreds of miles to the southwest of the latest model consensus.
Obviously this is a zero-confidence forecast tonight.

Marginally warm waters and moderate shear could support additional
strengthening of Leslie during the next day or two, although the
guidance is generally lower than yesterday. By Saturday, colder
ocean waters, higher shear and a drier mid-level atmosphere should
cause Leslie to weaken. No significant changes were made to the
previous intensity forecast. By Monday, Leslie, whether it follows
the forecast track or not, will likely be struggling to produce
convection or have already transitioned into an extratropical low.
Thus the 5 day point shows post-tropical status, perhaps
optimistically, but this seems like the most likely option for now.


FORECAST POSITIONS AND MAX WINDS

INIT 11/0300Z 27.9N 41.1W 70 KT 80 MPH
12H 11/1200Z 28.4N 39.4W 75 KT 85 MPH
24H 12/0000Z 29.9N 35.7W 75 KT 85 MPH
36H 12/1200Z 31.3N 30.5W 75 KT 85 MPH
48H 13/0000Z 32.3N 25.0W 70 KT 80 MPH
72H 14/0000Z 32.0N 20.0W 50 KT 60 MPH
96H 15/0000Z 29.5N 20.5W 35 KT 40 MPH
120H 16/0000Z 27.5N 25.0W 30 KT 35 MPH...POST-TROPICAL

$$
Forecaster Blake
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Re: ATL: LESLIE - Advisories

#51 Postby cycloneye » Thu Oct 11, 2018 4:58 am

Hurricane Leslie Discussion Number 60
NWS National Hurricane Center Miami FL AL132018
500 AM AST Thu Oct 11 2018

The cloud pattern of Leslie has not changed significantly
overnight. The hurricane has a large and ragged eye with deep
convection most organized on its east side. The Dvorak CI-numbers
are unchanged at 4.0/65 kt from TAFB and 4.5/77 kt from SAB, and
based on these data, the initial intensity is held at 70 kt.

Leslie will remain in low wind shear conditions and over relatively
warm waters for another day or two, so little change in strength is
expected during that time. Thereafter, the hurricane is forecast
to move over waters as cool as 24 deg C and into an atmospheric
environment of stronger shear and drier air. All of these
conditions point to a weakening trend, which is likely to begin by
the weekend. Most of the guidance shows a cold front approaching
Leslie, but not quite merging with it so extratropical transition is
not expected. However, it seems likely that Leslie will lose its
convection and become a weaker post-tropical low in about 4 days.
This scenario is supported by the latest runs of the GFS, ECMWF, and
HWRF models.

Leslie has made the expected east-northeastward turn with the latest
initial motion estimated to be 065/9. This east-northeastward motion
with an increase in forward speed is forecast to continue for the
next 2 days while the steering pattern holds. After that time,
however, it becomes much less clear. The models continue to
struggle and keep changing their tune cycle to cycle on whether or
not Leslie continues east-northeastward toward Morocco or Portugal,
or gets left behind and moves west-southwestward due to a building
ridge. The ensemble members of both the GFS and ECMWF favor the
left behind (or southwestward) solution, and the NHC track forecast
continues to lean in that direction. This forecast does show Leslie
moving farther east before it makes the southwestward turn to be in
better agreement with the latest consensus aids.

FORECAST POSITIONS AND MAX WINDS

INIT 11/0900Z 28.4N 40.1W 70 KT 80 MPH
12H 11/1800Z 29.3N 37.8W 75 KT 85 MPH
24H 12/0600Z 30.9N 33.3W 75 KT 85 MPH
36H 12/1800Z 32.1N 27.5W 70 KT 80 MPH
48H 13/0600Z 32.7N 22.3W 70 KT 80 MPH
72H 14/0600Z 31.3N 18.7W 50 KT 60 MPH
96H 15/0600Z 29.0N 19.5W 35 KT 40 MPH...POST-TROPICAL
120H 16/0600Z 27.5N 24.5W 30 KT 35 MPH...POST-TROP/REMNT LOW

$$
Forecaster Cangialosi
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Re: ATL: LESLIE - Advisories

#52 Postby cycloneye » Thu Oct 11, 2018 10:50 am

Hurricane Leslie Discussion Number 61
NWS National Hurricane Center Miami FL AL132018
1100 AM AST Thu Oct 11 2018

Leslie's structure has remained steady since last night. The
hurricane has a ragged banding eye surrounded by a somewhat patchy
central dense overcast. Recent Dvorak classifications from TAFB
and SAB are unchanged, and still support an initial intensity of
70 kt.

For days now, it has been clear that Leslie will accelerate
east-northeastward on the south side of a mid-latitude trough
moving across the North Atlantic. That acceleration is well underway
now, and the initial motion estimate is 060/14 kt. It has been
unclear, however, when (or if) Leslie could separate from this
trough and begin to drift southward over the eastern Atlantic. The
model spread has remarkably increased since yesterday, and nearly
1/3 of the members of the most recent GFS and ECMWF ensemble runs no
longer forecast Leslie to separate from the trough at all, instead
showing the cyclone approaching western Europe as an extratropical
low. Even the deterministic model spread has increased, and the
two NOAA regional hurricane models, the HWRF and HMON, are nearly
2300 miles apart at day 5. Through 48 h, the official track forecast
is very similar to the previous advisory, but it has been adjusted
eastward beyond that time, to bring it closer to the most recent
deterministic multi-model consensus. Confidence in the track
forecast is not high at 72 h and beyond, and it's possible that
large changes could still be required to future advisories.

Leslie should remain in a generally favorable environment for
strengthening during the next 24-36 h, and slight intensification
is still expected, though the official intensity forecast is now on
the high side of the guidance through this period. By 48 h and
onward, Leslie will be moving into a far more stable environment
and over cooler waters, so steady weakening is anticipated. If
Leslie follows a track similar to the NHC forecast, it will likely
become a weak post-tropical low within 96 h. However, if Leslie
undergoes extratropical transition, its worth noting that the
maximum winds associated with the cyclone would likely be higher
than indicated here.

FORECAST POSITIONS AND MAX WINDS

INIT 11/1500Z 29.1N 38.3W 70 KT 80 MPH
12H 12/0000Z 30.3N 35.5W 75 KT 85 MPH
24H 12/1200Z 31.7N 30.3W 75 KT 85 MPH
36H 13/0000Z 32.8N 24.6W 70 KT 80 MPH
48H 13/1200Z 33.2N 20.0W 60 KT 70 MPH
72H 14/1200Z 31.3N 17.3W 40 KT 45 MPH
96H 15/1200Z 29.1N 19.0W 30 KT 35 MPH...POST-TROPICAL
120H 16/1200Z 27.5N 24.0W 30 KT 35 MPH...POST-TROP/REMNT LOW

$$
Forecaster Zelinsky
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Re: ATL: LESLIE - Advisories

#53 Postby cycloneye » Thu Oct 11, 2018 3:49 pm

Hurricane Leslie Discussion Number 62
NWS National Hurricane Center Miami FL AL132018
500 PM AST Thu Oct 11 2018

Leslie's inner-core structure has improved a little during the day
today. A ragged banding eye was present in visible imagery until
sunset, though this feature is not apparent in IR imagery. Recent
satellite intensity estimates range from 65 kt to 90 kt, so Leslie's
intensity has been raised to 75 kt as a compromise of all available
estimates.

Leslie continues to accelerate east-northeastward with an initial
motion estimate of 065/18 kt. Confidence remains high that Leslie
will continue gaining speed on that heading for the next 24 h or
so. Beyond that time, the ensemble spread is still very high,
though the 12Z deterministic global models are generally in
agreement that Leslie will separate from a mid-level trough, slow
down, and turn southward over the weekend. While the exact timing of
this turn is still highly uncertain, the multi-model consensus
brings Leslie near Madeira Island on Saturday as a tropical storm.
The new official forecast shows a very similar track, and the
government of Portugal has issued a Tropical Storm Watch for that
island. While the exact path of Leslie is still uncertain, the
cyclone is still expected to produce tropical storm conditions over
a wide area through Saturday, and interests on Madeira should not
focus on the exact track of Leslie.

No large changes in intensity are anticipated during the next 24 h,
though some fluctuations are possible, up or down. By 36 h, Leslie
will reach much cooler waters and encounter an increase in wind
shear which should lead to steady weakening. The intensity guidance
is in surprisingly good agreement given the continued large track
spread, and the NHC intensity forecast is near the middle of the
guidance envelope from 36 h onward. By 96 h, odds are increasing
that Leslie could lose all of its convection and become
post-tropical, though this possibility still depends heavily on
Leslie following a track similar to the NHC official forecast.

FORECAST POSITIONS AND MAX WINDS

INIT 11/2100Z 29.9N 36.5W 75 KT 85 MPH
12H 12/0600Z 31.0N 33.0W 75 KT 85 MPH
24H 12/1800Z 32.5N 27.4W 75 KT 85 MPH
36H 13/0600Z 33.3N 21.6W 65 KT 75 MPH
48H 13/1800Z 33.1N 17.4W 55 KT 65 MPH
72H 14/1800Z 30.9N 16.0W 40 KT 45 MPH
96H 15/1800Z 29.0N 18.5W 30 KT 35 MPH...POST-TROPICAL
120H 16/1800Z 28.0N 24.0W 30 KT 35 MPH...POST-TROP/REMNT LOW

$$
Forecaster Zelinsky
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Re: ATL: LESLIE - Advisories

#54 Postby cycloneye » Thu Oct 11, 2018 9:43 pm

Hurricane Leslie Discussion Number 63
NWS National Hurricane Center Miami FL AL132018
1100 PM AST Thu Oct 11 2018

Satellite images indicate that Leslie has continued to strengthen.
A small eye has occasionally been apparent, although it has
recently become obscured by clouds. ASCAT data showed peak winds
of 75 kt earlier, and given the low bias of that instrument at those
wind speeds, the initial wind speed is set to 80 kt. Leslie should
begin to weaken in about 24 hours as the hurricane encounters cool
waters and a higher-shear environment. Intensity guidance is
tightly clustered around the previous NHC prediction, and little
change is made in the new advisory. By 72 hours, a combination of
very dry air aloft, waters near 23.5C, and high shear should cause
Leslie to lose convection and transition into a post-tropical
cyclone.

Leslie continues to accelerate east-northeastward with an initial
motion estimate of 070/23 kt. The hurricane should move rapidly
in that general direction for the next day or so ahead of a
mid-latitude trough, then bend eastward and southward as the main
steering mechanism switches to the eastern Atlantic subtropical
ridge. There is still a large guidance spread, over 700 miles at
day 3, but the main change to report is that more of the models are
continuing the east-northeastward track longer, possibly due to
Leslie becoming a stronger system. The official forecast is
shifted to the east, but is still well to the southwest of the
model consensus, ironically similar to last night's forecast.

Leslie is a fairly large tropical cyclone and the forecast wind
radii encompass Madeira Island within 36 hours. Consequently, a
tropical storm warning has been issued for that island. It is the
first known tropical storm warning for that place, and there are
no known tropical storms in the historical record anywhere
within 100 miles of that island, with the closest being Vince of
2005.

FORECAST POSITIONS AND MAX WINDS

INIT 12/0300Z 30.9N 33.9W 80 KT 90 MPH
12H 12/1200Z 32.1N 29.8W 80 KT 90 MPH
24H 13/0000Z 33.3N 23.5W 75 KT 85 MPH
36H 13/1200Z 34.0N 18.0W 65 KT 75 MPH
48H 14/0000Z 33.5N 15.5W 55 KT 65 MPH
72H 15/0000Z 31.5N 15.0W 35 KT 40 MPH...POST-TROPICAL
96H 16/0000Z 29.0N 18.0W 30 KT 35 MPH...POST-TROP/REMNT LOW
120H 17/0000Z 28.0N 24.0W 25 KT 30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Blake
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Re: ATL: LESLIE - Advisories

#55 Postby cycloneye » Fri Oct 12, 2018 4:51 am

Hurricane Leslie Discussion Number 64
NWS National Hurricane Center Miami FL AL132018
500 AM AST Fri Oct 12 2018

Leslie has changed little in organization since the last advisory.
The eye is currently not apparent in conventional satellite imagery,
although recent microwave overpasses indicate at least a partial
eyewall is present under the overcast. Satellite intensity
estimates have changed little, so the initial intensity is held at
80 kt.

The initial motion is now 065/24. The guidance is in good
agreement that this general motion should continue for 24 h or so.
After that, there is a major model divergence. The GFS, ECMWF, and
the various consensus models now show a continued east-northeast
motion until landfall in Portugal or Spain. On the other hand, the
UKMET, UK ensemble mean, and Canadian models show a turn toward the
south and then back to the west. Since the previous forecast showed
a southward and westward turn, the new forecast track will also
follow this scenario. However, it is shifted well to the east of
the previous track due to the forecasts of the other models.
Needless to say, the latter portion of the track forecast is low
confidence.

Leslie should gradually weaken as it approaches Madeira Island
during the next 24-36 h. After that, the intensity forecast is
dependent on what track the cyclone takes. If it follows the
GFS/ECMWF scenario, the system would likely make landfall on the
Iberian peninsula and quickly dissipate. If it follows the UKMET
scenario, a combination of shear, cool water, and dry air
entrainment should cause weakening. Since the track forecast is
closer to the UKMET scenario, the intensity forecast follows the
previous forecast in having Leslie decay to a post-tropical low by
72 h. However, this is also a low confidence forecast due to the
uncertainties in the track forecast.


FORECAST POSITIONS AND MAX WINDS

INIT 12/0900Z 31.9N 31.0W 80 KT 90 MPH
12H 12/1800Z 33.1N 26.5W 80 KT 90 MPH
24H 13/0600Z 34.2N 20.3W 75 KT 85 MPH
36H 13/1800Z 34.6N 15.5W 65 KT 75 MPH
48H 14/0600Z 34.0N 13.0W 50 KT 60 MPH
72H 15/0600Z 32.0N 12.0W 30 KT 35 MPH...POST-TROP/REMNT LOW
96H 16/0600Z 30.0N 13.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 17/0600Z 28.0N 18.0W 20 KT 25 MPH...POST-TROP/REMNT LOW

$$
Forecaster Beven
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Re: ATL: LESLIE - Advisories

#56 Postby cycloneye » Fri Oct 12, 2018 2:59 pm

Hurricane Leslie Discussion Number 65
NWS National Hurricane Center Miami FL AL132018
1100 AM AST Fri Oct 12 2018

Leslie's cloud pattern continues to feature a central dense
overcast, but with only hints of an eye in visible imagery. A
partial northern eyewall was noted on a 0910Z SSMIS overpass. Dvorak
intensity estimates have decreased slightly, and based on this, the
initial intensity has been conservatively nudged down to 75 kt. The
wind field is quite large, especially south of the center, as
confirmed by a pair of recent ASCAT passes, and the initial wind
radii have been adjusted using those data.

The initial motion estimate is now 070/28. Leslie is moving quickly
east-northeastward on the southern side of a powerful longwave
trough centered over the north Atlantic. The track forecast
reasoning has changed since the last advisory, with the GFS, ECMWF,
and now the 06Z run of the UKMET all showing a more eastward motion
of Leslie toward the Iberian Peninsula as the cyclone is picked up
by the aforementioned trough. The new NHC track forecast has been
adjusted significantly to the north and east, especially beyond 24
hours, but still lies to the south of and is slower than the GFS and
ECMWF. Once the system moves inland, the low-level center should
dissipate over the high terrain, but a 72 hour remnant low point is
included for continuity purposes. Needless to say, confidence in the
official track forecast beyond 24 hours is quite low given the
recent shift in the models, and further adjustments will likely be
necessary.

The intensity forecast shows Leslie only slowly weakening as a
tropical cyclone during the next 24 hours due to a combination of
cool SSTs and increasing shear from the trough. However, simulated
satellite imagery and model fields suggest that Leslie will
transition to a powerful post-tropical cyclone by 36 hours, likely
still at hurricane intensity as shown by the global models.
Weakening is expected after the trough passes Leslie by, and the
mid-level circulation will likely be sheared away by strong
upper-level winds.

Leslie is expected to bring significant rain and wind impacts to
portions of Portugal and Spain by Sunday, and residents in those
areas should refer to products from their local meteorological
services for more information on these hazards.

FORECAST POSITIONS AND MAX WINDS

INIT 12/1500Z 33.0N 28.0W 75 KT 85 MPH
12H 13/0000Z 34.2N 23.0W 70 KT 80 MPH
24H 13/1200Z 35.4N 17.0W 65 KT 75 MPH
36H 14/0000Z 36.0N 12.5W 65 KT 75 MPH...POST-TROPICAL
48H 14/1200Z 36.3N 9.1W 50 KT 60 MPH...POST-TROPICAL
72H 15/1200Z 37.0N 4.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 16/1200Z...DISSIPATED

$$
Forecaster Brennan
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Re: ATL: LESLIE - Advisories

#57 Postby cycloneye » Fri Oct 12, 2018 3:38 pm

BULLETIN
Hurricane Leslie Advisory Number 66
NWS National Hurricane Center Miami FL AL132018
500 PM AST Fri Oct 12 2018

...HURRICANE LESLIE RACING ACROSS THE FAR EASTERN ATLANTIC...
...EXPECTED TO BRING SIGNIFICANT WIND AND RAIN IMPACTS TO PORTIONS
OF PORTUGAL AND SPAIN SATURDAY NIGHT AND SUNDAY...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...33.9N 24.1W
ABOUT 895 MI...1445 KM SSW OF LISBON PORTUGAL
ABOUT 405 MI...650 KM WNW OF THE AZORES
MAXIMUM SUSTAINED WINDS...85 MPH...140 KM/H
PRESENT MOVEMENT...ENE OR 70 DEGREES AT 35 MPH...56 KM/H
MINIMUM CENTRAL PRESSURE...971 MB...28.68 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:

None.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Tropical Storm Warning is in effect for...
* Madeira Island

Interests in the Portugal and Spain should monitor the progress of
Leslie. Additional information on this system can be found in
products from the Portuguese Institute for Sea and Atmosphere at
www.ipma.pt. Interests in Spain should refer to products from the
State Meteorological Agency at www.aemet.es.



Hurricane Leslie Discussion Number 66
NWS National Hurricane Center Miami FL AL132018
500 PM AST Fri Oct 12 2018

Leslie remains a well organized tropical cyclone, with a fairly
symmetric central dense overcast, and hints of an eye in both
conventional and microwave satellite imagery. A 1738 UTC SSMIS
microwave overpass shows that there is some northeast to southwest
tilt, due to an increase in westerly shear. Some slight weakening
is foreast tonight while Leslie moves over cool SSTs of 23 to 24
degrees Celsius and into an area of increasing westerly shear.
However, Leslie is forecast to transition into a powerful hurricane-
force post-tropical cyclone in about 24 hours as it interacts with
an approaching trough. The post-tropical cyclone is expected to make
landfall along the west coast of the Iberian Peninsula shortly
thereafter, and it should weaken due to land interaction after that
time. The system is forecast to dissipate inland by Monday.

Leslie continues to race across the far eastern Atlantic, with an
initial motion estimate of 070/30 kt. The global models are now
unanimous in taking Leslie quickly east-northeastward on the south
side of a strong longwave trough over the northeast Atlantic. The
official track foreast as been adjusted northward and is
significantly faster than before, and brings the center of Leslie
over the coast of the Iberian Peninsula by 0000 UTC Sunday. The
system is likely to dissipate over the high terrain of Spain
within a couple of days, but a 48-h forecast point is shown for
continuity. Now that the track guidance is in much better
agreement, confidence in the NHC track forecast has increased.

After coordination with the meteorological services of Portugal and
Spain, they have decided to provide information on the wind hazard
with local products.

Key Messages:

1. Leslie is expected to bring near hurricane-force winds on
Saturday to portions of Portugal as a powerful post-tropical
cyclone. Tropical-storm-force winds are also likely to affect
portions of western Spain.

2. Leslie is expected to produce rainfall amounts of 25 to 75 mm (1
to 3 inches) with isolated amounts as high as 100 mm (4 inches)
across portions of Portugal and Spain, which could cause flash
flooding.

3. For more information on Leslie, interests in Portugal should
refer to products from the Portuguese Institute for Sea and
Atmosphere at www.ipma.pt. Interests in Spain should refer to
products from the State Meteorological Agency at www.aemet.es.

FORECAST POSITIONS AND MAX WINDS

INIT 12/2100Z 33.9N 24.1W 75 KT 85 MPH
12H 13/0600Z 35.6N 18.8W 70 KT 80 MPH
24H 13/1800Z 38.0N 12.0W 65 KT 75 MPH...POST-TROPICAL
36H 14/0600Z 40.6N 6.5W 45 KT 50 MPH...POST-TROPICAL/INLAND
48H 14/1800Z 43.0N 2.0W 30 KT 35 MPH...POST-TROPICAL/INLAND
72H 15/1800Z...DISSIPATED

$$
Forecaster Brown
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Re: ATL: LESLIE - Advisories

#58 Postby cycloneye » Fri Oct 12, 2018 9:35 pm

BULLETIN
Hurricane Leslie Intermediate Advisory Number 66A
NWS National Hurricane Center Miami FL AL132018
800 PM AST Fri Oct 12 2018

...LESLIE PASSING BETWEEN THE AZORES AND MADEIRA ISLAND...
...DANGEROUS WINDS, SURF, AND HEAVY RAINFALL EXPECTED TO AFFECT
PORTIONS OF PORTUGAL AND SPAIN SATURDAY NIGHT AND SUNDAY...


SUMMARY OF 800 PM AST...0000 UTC...INFORMATION
----------------------------------------------
LOCATION...34.4N 22.4W
ABOUT 795 MI...1280 KM WSW OF LISBON PORTUGAL
ABOUT 320 MI...515 KM WNW OF MADEIRA ISLAND
MAXIMUM SUSTAINED WINDS...85 MPH...140 KM/H
PRESENT MOVEMENT...ENE OR 70 DEGREES AT 35 MPH...56 KM/H
MINIMUM CENTRAL PRESSURE...972 MB...28.70 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:

None.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Tropical Storm Warning is in effect for...
* Madeira Island

Interests in the Portugal and Spain should monitor the progress of
Leslie. Additional information on this system can be found in
products from the Portuguese Institute for Sea and Atmosphere at
www.ipma.pt. Interests in Spain should refer to products from the
State Meteorological Agency at www.aemet.es.
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Re: ATL: LESLIE - Advisories

#59 Postby cycloneye » Fri Oct 12, 2018 9:40 pm

BULLETIN
Hurricane Leslie Advisory Number 67
NWS National Hurricane Center Miami FL AL132018
1100 PM AST Fri Oct 12 2018

...LESLIE DASHING EAST-NORTHEASTWARD TOWARD THE IBERIAN PENINSULA...
...DANGEROUS WINDS, SURF, AND HEAVY RAINFALL EXPECTED TO AFFECT
PORTIONS OF PORTUGAL AND SPAIN SATURDAY NIGHT AND SUNDAY...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...34.7N 20.7W
ABOUT 690 MI...1125 KM WSW OF LISBON PORTUGAL
ABOUT 240 MI...385 KM NW OF MADEIRA ISLAND
MAXIMUM SUSTAINED WINDS...80 MPH...130 KM/H
PRESENT MOVEMENT...ENE OR 75 DEGREES AT 36 MPH...57 KM/H
MINIMUM CENTRAL PRESSURE...976 MB...28.82 INCHES



Hurricane Leslie Discussion Number 67
NWS National Hurricane Center Miami FL AL132018
1100 PM AST Fri Oct 12 2018

Although Leslie continues to produce a compact area of deep
convection, microwave data since the previous advisory indicate
that the mid-level center is becoming more separated from the
low-level center due to increasing shear. Dvorak final-T numbers
have begun to decrease a bit, and the initial intensity is
therefore set at 70 kt. A cold front is beginning to wrap around
the western side of Leslie's circulation, and the global models
indicate that the cyclone should lose its warm core and become
fully embedded within the frontal zone by 24 hours, if not sooner.
Despite sea surface temperatures of 17-23 degrees Celsius ahead of
Leslie, baroclinic forcing is likely to maintain the system's
intensity as it becomes extratropical. As a result, Leslie is
forecast to reach the Iberian Peninsula as a hurricane-force
extratropical low, with the NHC intensity forecast most closely
following the GFS guidance. Rapid weakening is forecast once the
low moves inland, and the system should dissipate over the higher
terrain of Spain in about 48 hours.

The forward motion is east-northeastward, or 075/31 kt. Located
within the base of a progressive trough, Leslie should maintain
this trajectory, slowing down only a little bit before it reaches
Portugal and Spain in 24-36 hours. Except for the UKMET model,
which shows Leslie turning more northeastward toward the
northwestern Iberian Peninsula, the rest of the track guidance is
tightly clustered and brings the center inland across central
Portugal and western Spain. Because most of the models are in good
agreement and are close to the previous official forecast, no
significant changes were made to the NHC forecast on this cycle.

Based on coordination from earlier today, the meteorological
services of Portugal and Spain will handle hazard information for
their respective countries via local weather products.


Key Messages:

1. Leslie is expected to bring near hurricane-force winds to
portions of Portugal late Saturday as a powerful post-tropical
cyclone. Gale-force winds are also likely to affect portions of
western Spain Saturday night and Sunday.

2. Leslie is expected to produce rainfall amounts of 25 to 75 mm (1
to 3 inches) with isolated amounts as high as 100 mm (4 inches)
across portions of Portugal and Spain, which could cause flash
flooding.

3. For more information on Leslie, interests in Portugal should
refer to products from the Portuguese Institute for Sea and
Atmosphere at www.ipma.pt. Interests in Spain should refer to
products from the State Meteorological Agency at www.aemet.es.


FORECAST POSITIONS AND MAX WINDS

INIT 13/0300Z 34.7N 20.7W 70 KT 80 MPH
12H 13/1200Z 36.5N 15.4W 65 KT 75 MPH
24H 14/0000Z 38.9N 9.4W 65 KT 75 MPH...POST-TROP/EXTRATROP
36H 14/1200Z 41.0N 5.1W 40 KT 45 MPH...POST-TROP/EXTRATROP
48H 15/0000Z 42.3N 1.1W 25 KT 30 MPH...POST-TROP/EXTRATROP
72H 16/0000Z...DISSIPATED

$$
Forecaster Berg
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Re: ATL: LESLIE - Advisories

#60 Postby cycloneye » Sat Oct 13, 2018 5:08 am

BULLETIN
Hurricane Leslie Advisory Number 68
NWS National Hurricane Center Miami FL AL132018
500 AM AST Sat Oct 13 2018

...LESLIE WEAKENS SLIGHTLY AS IT CONTINUES MOVING EAST-NORTHEASTWARD
TOWARD THE IBERIAN PENINSULA...
...DANGEROUS WINDS, SURF, AND HEAVY RAINFALL EXPECTED TO AFFECT
PORTIONS OF PORTUGAL AND SPAIN TONIGHT AND SUNDAY...


SUMMARY OF 500 AM AST...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...36.2N 16.7W
ABOUT 580 MI...935 KM E OF THE AZORES
ABOUT 680 MI...1090 KM E OF FAIAL ISLAND IN THE CENTRAL AZORES
MAXIMUM SUSTAINED WINDS...75 MPH...120 KM/H
PRESENT MOVEMENT...ENE OR 70 DEGREES AT 38 MPH...61 KM/H
MINIMUM CENTRAL PRESSURE...980 MB...28.94 INCHES



Hurricane Leslie Discussion Number 68
NWS National Hurricane Center Miami FL AL132018
500 AM AST Sat Oct 13 2018

Satellite imagery suggests that Leslie has started extratropical
transition. The mid-level eye seen earlier in both conventional
and microwave satellite imagery has become less distinct, and it is
continuing to separate from the low-level center. In addition,
colder air is entraining into the western and southern sides of the
circulation. However, a sizable cluster of convection persists to
the northeast of the center, indicating that the cyclone is still
tropical at this time. The large-scale models forecast that Leslie
will likely complete transition in 12 to perhaps 18 h, and that the
associated winds should remain at or near hurricane force until the
center moves over the Iberian Peninsula. After landfall, rapid
weakening is forecast, and the cyclone should dissipate as it
becomes part of a broad low pressure area over Spain between 36-48
h.

The initial motion is 070/33 as Leslie is now well embedded in the
mid-latitude westerlies. A continued east-northeastward motion with
a gradual decrease in forward speed is expected for the next 36 h.
This should bring the center of Leslie onshore on the Iberian
Peninsula in about 18 h and into western Spain by about 24 h. There
is little change in either the track guidance or the track forecast
from the last advisory.

The meteorological services of Portugal and Spain will handle hazard
information for their respective countries via local weather
products.


Key Messages:

1. Leslie is expected to bring near hurricane-force winds to
portions of Portugal late today as a powerful post-tropical
cyclone. Gale-force winds are also likely to affect portions of
western Spain tonight and Sunday.

2. Leslie is expected to produce rainfall amounts of 25 to 75 mm (1
to 3 inches) with isolated amounts as high as 125 mm (5 inches)
across portions of Portugal and Spain, which could cause flash
flooding.

3. For more information on Leslie, interests in Portugal should
refer to products from the Portuguese Institute for Sea and
Atmosphere at http://www.ipma.pt. Interests in Spain should refer to
products from the State Meteorological Agency at http://www.aemet.es.


FORECAST POSITIONS AND MAX WINDS

INIT 13/0900Z 36.2N 16.7W 65 KT 75 MPH
12H 13/1800Z 37.7N 11.8W 65 KT 75 MPH...POST-TROP/EXTRATROP
24H 14/0600Z 39.6N 6.8W 35 KT 40 MPH...POST-TROP/INLAND
36H 14/1800Z 41.3N 2.7W 25 KT 30 MPH...POST-TROP/INLAND
48H 15/0600Z...DISSIPATED

$$
Forecaster Beven
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