ATL: LISA - Post-Tropical - Discussion

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Re: ATL: LISA - Advisories

#61 Postby cycloneye » Wed Sep 21, 2016 9:42 am

TROPICAL STORM LISA DISCUSSION NUMBER 8
NWS NATIONAL HURRICANE CENTER MIAMI FL AL132016
1100 AM AST WED SEP 21 2016

The cloud pattern of Lisa has not changed much since the previous
advisory. A 0911 UTC SSMIS image suggested that the low-level
center was located on the western edge of the central convection.
The 12Z Dvorak Data-T numbers from SAB and TAFB decreased and a
partial ASCAT-B pass from 1115 UTC only showed 30-35 kt winds in the
northeastern quadrant. However, the initial intensity is held at 45
kt given the lack of clear evidence of weakening and in agreement
with the the latest Dvorak CI numbers of T3.0/45 kt. There is only
a small opportunity for the cyclone to strengthen before the shear
increases even further in 24 to 36 hours. Weakening is expected
after that time, and later in the period, as the mid-level
environment becomes quite dry, the cyclone should weaken to a
remnant low. The new NHC intensity forecast is similar to the
previous one and is near the middle of the guidance in the first 36
hours and then is near or below the weaker LGEM solution after that
time.

The initial motion estimate is a somewhat uncertain 320/07, given
the lack of confidence in the location of the center. Lisa will
move northwestward during the next 72 hours into a weakness in the
subtropical ridge over the eastern Atlantic, and then recurve into
the mid-latitude westerlies on days 4 and 5. The global models are
in generally good agreement on this scenario, with the ECMWF lying
on the left side of the guidance cluster and the GFS shifting to the
right this cycle. The new NHC track forecast is an update of the
previous one but has been adjusted for the initial position and
motion. This forecast is near a blend of the latest GFS and ECMWF
tracks and is well to the left of the GFDL and HWRF models, which
lie nearly 200 n mi east of the rest of the guidance at days 3 and
4.

FORECAST POSITIONS AND MAX WINDS

INIT 21/1500Z 18.0N 32.5W 45 KT 50 MPH
12H 22/0000Z 18.6N 33.4W 50 KT 60 MPH
24H 22/1200Z 19.7N 34.9W 45 KT 50 MPH
36H 23/0000Z 20.9N 36.5W 45 KT 50 MPH
48H 23/1200Z 22.3N 38.0W 40 KT 45 MPH
72H 24/1200Z 25.0N 41.0W 30 KT 35 MPH
96H 25/1200Z 28.5N 43.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 26/1200Z 34.0N 41.0W 25 KT 30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Brennan
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Re: ATL: LISA - Models

#62 Postby Hammy » Wed Sep 21, 2016 12:28 pm

GFS keeps Lisa through 120 hours, taking it to near hurricane intensity--interestingly none of the previous Lisa's were forecast to hurricane intensity but reached it nonetheless.
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Re: ATL: LISA - Tropical Storm - Discussion

#63 Postby HurricaneRyan » Thu Sep 22, 2016 10:12 am

Another dead thread. Wow!
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Re: ATL: LISA - Tropical Storm - Discussion

#64 Postby SeGaBob » Thu Sep 22, 2016 12:47 pm

HurricaneRyan wrote:Another dead thread. Wow!

What's there to talk about? A weak storm 4000 miles or more from the U.S isn't interesting at all.
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Re: ATL: LISA - Tropical Storm - Discussion

#65 Postby Hammy » Thu Sep 22, 2016 12:57 pm

abajan wrote:
HurricaneRyan wrote:... I hope she becomes a hurricane again at least.

Unlikely. At least, according to the latest NHC. But time will tell.


The Lisa-named storms have a habit of pulling surprises.
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Re: ATL: LISA - Advisories

#66 Postby cycloneye » Fri Sep 23, 2016 5:57 pm

TROPICAL DEPRESSION LISA DISCUSSION NUMBER 17
NWS NATIONAL HURRICANE CENTER MIAMI FL AL132016
500 PM AST FRI SEP 23 2016

All of the deep convection has been removed far from the center of
Lisa by continued strong southwesterly shear of around 40 kt. The
initial intensity has been lowered to 30 kt based on the latest
Dvorak estimate from TAFB. At this point, with a combination of
strong shear, marginal SSTs and a drying mid-level atmosphere, it
seems unlikely that Lisa will regain organized deep convection, so
remnant low status is now indicated by 24 hours. The weak cyclone
should dissipate by 72 hours in fast southwesterly flow ahead of an
approaching deep-layer trough.

The initial motion has been rather slow today, and is currently
estimated as 310/06. The increasingly shallow cyclone is expected
to turn west-northwestward tonight and then recurve between 36 and
48 hours as the deep-layer trough approaches from the west. The new
NHC track forecast is a little to the left of the previous one after
12 hours, reflecting a westward shift in the guidance that is
probably responding to Lisa's weakening. This forecast is close to
the middle of the guidance envelope and near the latest guidance
from the Ocean Prediction Center.

FORECAST POSITIONS AND MAX WINDS

INIT 23/2100Z 22.5N 36.5W 30 KT 35 MPH
12H 24/0600Z 23.4N 38.0W 30 KT 35 MPH
24H 24/1800Z 24.4N 40.1W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 25/0600Z 26.0N 42.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 25/1800Z 27.9N 42.3W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 26/1800Z...DISSIPATED

$$
Forecaster Brennan
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Re: ATL: LISA - Advisories

#67 Postby cycloneye » Fri Sep 23, 2016 11:06 pm

TROPICAL DEPRESSION LISA DISCUSSION NUMBER 18
NWS NATIONAL HURRICANE CENTER MIAMI FL AL132016
1100 PM AST FRI SEP 23 2016

Lisa continues to suffer from strong vertical wind shear. There has
been no deep convection within 120 nm of the center for nearly 12
hours now, though occasional bursts of convection have been noted a
little farther than that to the north. A 2324 ASCAT-B pass showed
several 35-kt wind vectors between the center and the convection
farther to the north. Based on this new information, it is believed
that Lisa was still a tropical storm at the time of the previous
advisory and at 0000 UTC. Given the lack of deep convection since
that time, the initial intensity has been held at 30 kt. Regardless
of the maximum winds, the dynamical guidance all suggest that the
strong shear and dry mid- and upper-level air will continue to
suppress convection near the center, and Lisa is forecast to be
declared post-tropical within 12 hours. The remnant circulation
should last a day or two after that, before dissipating ahead of a
deep-layer trough approaching from the west.

The depression may finally be beginning to speed up, and the initial
motion estimate is 315/07. The low-level remnants of Lisa are
still forecast to move west-northwestward, with a gradual turn
toward the north in a day or two while it moves around the periphery
of the subtropical high centered near the Azores. The official
forecast has again been nudged westward, but lies a little to the
right of the model consensus.


FORECAST POSITIONS AND MAX WINDS

INIT 24/0300Z 23.2N 37.3W 30 KT 35 MPH
12H 24/1200Z 23.9N 38.7W 30 KT 35 MPH...POST-TROP/REMNT LOW
24H 25/0000Z 25.0N 40.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 25/1200Z 26.4N 42.3W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 26/0000Z 28.8N 42.7W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 27/0000Z...DISSIPATED

$$
Forecaster Beven/Zelinsky
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Re: ATL: LISA - Advisories

#68 Postby cycloneye » Sat Sep 24, 2016 5:37 am

TROPICAL DEPRESSION LISA DISCUSSION NUMBER 19
NWS NATIONAL HURRICANE CENTER MIAMI FL AL132016
500 AM AST SAT SEP 24 2016

A strong burst of convection has recently formed in the northeastern
quadrant of Lisa. Overall, however, the system looks less organized
than it did yesterday, with the low-level circulation becoming
elongated from north to south. The initial wind speed is held at 30
kt in agreement with the TAFB satellite classification. Although
there is only limited skill in forecasting deep convection, this
burst is expected to be ephemeral due to strong shear and dry air
aloft. Thus, Lisa is still forecast to be a remnant low by this
evening. The global models show Lisa weakening and opening up into
a trough within 2 days, and so will the NHC prediction.

The initial motion is a bit faster than earlier, now 315/08. Lisa,
or its remnants, are still forecast to move west-northwestward,
with a gradual turn toward the north in a day or two while it moves
around the periphery of the subtropical high centered near the
Azores. The official forecast is close to the previous one and the
model consensus.

FORECAST POSITIONS AND MAX WINDS

INIT 24/0900Z 23.8N 37.9W 30 KT 35 MPH
12H 24/1800Z 24.6N 39.3W 30 KT 35 MPH...POST-TROP/REMNT LOW
24H 25/0600Z 26.0N 41.2W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 25/1800Z 28.0N 42.2W 20 KT 25 MPH...POST-TROP/REMNT LOW
48H 26/0600Z...DISSIPATED

$$
Forecaster Blake
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Re: ATL: LISA - Advisories

#69 Postby cycloneye » Sat Sep 24, 2016 9:41 am

TROPICAL STORM LISA DISCUSSION NUMBER 20
NWS NATIONAL HURRICANE CENTER MIAMI FL AL132016
1100 AM AST SAT SEP 24 2016

The convective burst that occurred overnight has separated from the
low-level center of Lisa and is now nearly dissipated. This leaves
Lisa as a tight swirl of low-level clouds once again. An ASCAT-B
pass around 1200 UTC indicated that maximum winds were close to 40
kt, but given the degradation of the cloud pattern since the pass
the initial wind speed is set at 35 kt. This makes Lisa a tropical
storm again. Even though Lisa is a little stronger than estimated
earlier, the intensity forecast is unchanged from the previous
one. Continued strong shear and dry air should cause a gradual
decay of the cyclone, and Lisa will likely become a remnant low by
tonight. The models are in good agreement in showing the remnant
low opening into a trough in 36 to 48 hours before it becomes
absorbed by a cold front.

Lisa is moving northwestward at 9 kt. A west-northwestward to
northwestward motion at about the same speed is expected during the
next 24 hours as Lisa remains steered by a high pressure system to
its north. A motion more toward the north is forecast to occur on
Sunday as the high shifts eastward to near the Azores. Only small
adjustments were made to the previous NHC track prediction, and it
lies close to a consensus of the GFS and ECMWF models.

FORECAST POSITIONS AND MAX WINDS

INIT 24/1500Z 24.7N 38.8W 35 KT 40 MPH
12H 25/0000Z 25.7N 40.1W 30 KT 35 MPH...POST-TROP/REMNT LOW
24H 25/1200Z 27.4N 41.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 26/0000Z 29.3N 42.1W 20 KT 25 MPH...POST-TROP/REMNT LOW
48H 26/1200Z...DISSIPATED

$$
Forecaster Cangialosi
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Re: ATL: LISA - Tropical Storm - Discussion

#70 Postby AnnularCane » Sat Sep 24, 2016 9:44 am

Hammy wrote:The Lisa-named storms have a habit of pulling surprises.


Maybe so, guess who's a TS again? :lol:
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Re: ATL: LISA - Tropical Storm - Discussion

#71 Postby Hammy » Sat Sep 24, 2016 1:46 pm

AnnularCane wrote:
Hammy wrote:The Lisa-named storms have a habit of pulling surprises.


Maybe so, guess who's a TS again? :lol:


Looks like not only that, they've gone back and revised the BT now showing it having never weakened to a depression.
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Re: ATL: LISA - Advisories

#72 Postby cycloneye » Sat Sep 24, 2016 4:09 pm

TROPICAL DEPRESSION LISA DISCUSSION NUMBER 21
NWS NATIONAL HURRICANE CENTER MIAMI FL AL132016
500 PM AST SAT SEP 24 2016

Lisa has been devoid of thunderstorm activity since the convective
burst dissipated shortly after 1200 UTC. Assuming some additional
spin down since the ASCAT pass this morning, the initial wind speed
is lowered to 30 kt, making Lisa a tropical depression again.
Meteosat dust product images from the GOES-R Proving Ground indicate
that a plume of Saharan dust is approaching Lisa from the east. This
dry air combined with westerly shear should cause the depression to
degenerate to a remnant low by tonight and continue weakening during
the next day or two. The global models are in fair agreement in
showing the low opening into a trough in 36 to 48 hours before it
gets absorbed by a cold front.

Lisa is moving northwestward at 10 kt. A gradual turn to the north
is expected during the next day or two while the high pressure
system to the north of Lisa shifts eastward. The NHC track forecast
is slightly to the left of the previous one, and is in best
agreement with the various consensus aids.

FORECAST POSITIONS AND MAX WINDS

INIT 24/2100Z 25.3N 39.7W 30 KT 35 MPH
12H 25/0600Z 26.4N 41.1W 30 KT 35 MPH...POST-TROP/REMNT LOW
24H 25/1800Z 28.4N 42.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 26/0600Z 30.5N 42.4W 20 KT 25 MPH...POST-TROP/REMNT LOW
48H 26/1800Z...DISSIPATED

$$
Forecaster Cangialosi
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Re: ATL: LISA - Tropical Depression - Discussion

#73 Postby USTropics » Sat Sep 24, 2016 8:52 pm

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Re: ATL: LISA - Tropical Depression - Discussion

#74 Postby hurricanes1234 » Sat Sep 24, 2016 10:07 pm

Bye Lisa. :(

000
WTNT43 KNHC 250240
TCDAT3

POST-TROPICAL CYCLONE LISA DISCUSSION NUMBER 22
NWS NATIONAL HURRICANE CENTER MIAMI FL AL132016
1100 PM AST SAT SEP 24 2016

No deep convection was observed near the center of Lisa between
1200 UTC yesterday and 0200 UTC today. Although one small areas of
convection has tried to develop since then, it is insufficient to
meet the organized deep convection requirement for a tropical
cyclone. Yesterday's overnight burst of convection seems to have
been supported in part by an upper level low, however Lisa has now
moved farther to the west of that feature. In the absence of any
other synoptic-scale forcing, the redevelopment of widespread deep
convection is unlikely. No new scatterometer data is available
tonight, so the initial intensity has been held at 30 kt. Without
any convection to maintain the circulation, Lisa should gradually
spin down over the next day or so before dissipating ahead of a
deep-layer trough approaching from the west.

The low-level remnants of Lisa are moving around a high pressure
system centered near the Azores. The global models are in good
agreement that this high will move retreat eastward over the next
day or so, which should cause Lisa to turn toward the north in
12-24 hours. A turn toward the north-northeast ahead of the
approaching front is possible before the circulation dissipates
entirely.


FORECAST POSITIONS AND MAX WINDS

INIT 25/0300Z 25.8N 40.8W 30 KT 35 MPH...POST-TROP/REMNT LOW
12H 25/1200Z 27.2N 42.2W 30 KT 35 MPH...POST-TROP/REMNT LOW
24H 26/0000Z 29.3N 42.4W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 26/1200Z 31.4N 42.1W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 27/0000Z...DISSIPATED

$$
Forecaster Beven/Zelinsky
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