EPAC: LESTER - Post-Tropical

[Kingarabian]

Cycloneye, that's the NHC's previous discussion .

[Kingarabian]

WTPA41 PHFO 010317
TCDCP1

HURRICANE LESTER DISCUSSION NUMBER 30
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP132016
500 PM HST WED AUG 31 2016

The eye of Lester is becoming less distinct in visible satellite
imagery and the surrounding convective ring temperatures are
gradually warming in the infrared imagery. The intensity estimates
from the various agencies have responded accordingly, dropping to
5.5 (102 kt) from both HFO and SAB, and 4.5 (77 kt) from JTWC. Have
lowered the initial intensity to 105 kt for this advisory.

The initial motion estimate is 280/12, little change from the
previous advisory. The cyclone is moving just north of due west,
and is located south of a large deep layer anticyclone far to
the north-northwest. Not much change is expected for the next
few days as the cyclone continues to move toward Hawaii. The
guidance has been reasonably consistent in the days 3-4 time frame
showing Lester passing uncomfortably close to the islands. Little
change was made to the previous official forecast, which is in good
agreement with the TVCN consensus. A note of caution, despite the
consistent track forecast showing Lester passing just northeast of
the islands, it must be pointed out that there are plausible
solutions within the margin of error that show direct impacts to
the main Hawaiian Islands. This possibility must be considered for
planning preparations over the next couple of days.

Little change in the intensity forecast was made as well. Lester is
expected to track over marginal SSTs, but in a relative low shear
environment for the next few days. This will likely only result in
slow weakening. Our intensity forecast continues to split the
difference between the GFS/ECMWF, which maintain a stronger system,
and the HWRF and statistical guidance, which weaken Lester somewhat
faster.


FORECAST POSITIONS AND MAX WINDS

INIT 01/0300Z 18.2N 141.2W 105 KT 120 MPH
12H 01/1200Z 18.5N 143.1W 105 KT 120 MPH
24H 02/0000Z 18.9N 145.5W 100 KT 115 MPH
36H 02/1200Z 19.7N 148.1W 90 KT 105 MPH
48H 03/0000Z 20.3N 150.5W 80 KT 90 MPH
72H 04/0000Z 21.9N 155.9W 70 KT 80 MPH
96H 05/0000Z 24.1N 161.0W 60 KT 70 MPH
120H 06/0000Z 26.5N 165.4W 50 KT 60 MPH

$$
Forecaster R Ballard

[Kingarabian]

He should've included that the GFS and Euro ensembles have a large spread

[Alyono]

I'd like to know how JTWC has this as a 4.5

[Kingarabian]

00z GFS bit more north. Not sure if it's a landfall or not on Oahu. Is the G-V info in this model suite?

[Alyono]

Looks to be encountering some moderate to strong shear. Starting to be undercut like Madeline was

[Kingarabian]

Looks to be encountering some moderate to strong shear. Starting to be undercut like Madeline was

It's overachieving being at 959mb right now. GFS and Euro and the HWRF/GFDL have this nothing lower than 980mb as it nears Hawaii.

[Yellow Evan]

Looks to be encountering some moderate to strong shear. Starting to be undercut like Madeline was

Global models appear to be underdoing shear again.

[Kingarabian]

Looks to be encountering some moderate to strong shear. Starting to be undercut like Madeline was

Global models appear to be underdoing shear again.

Nothing on the CIMSS charts show the shear as well.

[Kingarabian]

I think the shear is minimal. It was there all of last night (the south eastern flank of Lester's CDO was flat). But the difference now is that waters are cooler due to the wake left behind from Madeline. I think it'll eventually recover.

[Alyono]

weakening rapidly now. It has also decided to move over nearly the exact track that Madeline did

[Kingarabian]

weakening rapidly now. It has also decided to move over nearly the exact track that Madeline did

Euro detected Madeline weakening before any other model. Let's see what it does in its 00z run.

[Alyono]

EC has a suspicious turn to the WNW with dramatic weakening between 48 and 72 hours. I wonder if it senses an upper trough

The ensemble PDF is right through the islands

[Kingarabian]

EC has a suspicious turn to the WNW with dramatic weakening between 48 and 72 hours. I wonder if it senses an upper trough

The ensemble PDF is right through the islands

For both the GFS and the Euro?

[Alyono]

EC has a suspicious turn to the WNW with dramatic weakening between 48 and 72 hours. I wonder if it senses an upper trough

The ensemble PDF is right through the islands

For both the GFS and the Euro?

EC, MU, and Canadian ensembles

[cycloneye]

HURRICANE LESTER DISCUSSION NUMBER 31
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP132016
1100 PM HST WED AUG 31 2016

Lester's satellite presentation has degraded over the past few
hours, with the eye gradually becoming cloud-filled. Convective
cloud tops around the eye have warmed and are now in the -63 to
-66 degree Celsius range. Little or no shear deformation is
noted, with outflow best to the north and northeast. Subjective
Dvorak satellite intensity estimates are 4.5/77 kt from JTWC, 5.0/90
kt from PHFO and 5.5/102 kt from SAB. We will assign Lester an
initial intensity of 95 kt for this advisory cycle, based on a rough
average of these three intensity estimates.

Initial motion is 275/12 kt as Lester moves generally westward
along the southern flank of a strong subtropical ridge. Upper
troughing expected to persist over and northwest of the main
Hawaiian Islands should allow Lester to gradually begin curving west
northwest, then northwest through the 5 day forecast period. Track
guidance remains tightly packed through 48 hours, then begins to
spread out afterwards. There is little change in the overall
envelope location from last time, but GFS shifted noticeably to the
right within it, joining ECMWF and HWRF depicting a gently curving
track just northeast of the Islands late day 2 through 4. The
little-changed forecast track roughly follows TVCN consensus along
this same general path. However, it is important to note that
several models along the left side of the guidance envelope, most
notably GFDL and UKMI, continue to show Lester passing over the
Islands as it curves northwestward. It would take only a small
leftward shift in the track to directly and profoundly affect the
Islands. This possibility must be considered when making preparation
plans over the next couple of days.

Lester has begun to weaken and most intensity guidance shows this
trend will continue through the 5 day forecast period, but at
differing rates. SHIPS, based mainly on decreasing SST potential,
weakens Lester most quickly, reducing this system to a tropical
storm within 48 hours. HWRF and the global models keep Lester much
stronger, with GFS keeping Lester as a hurricane at 120 hours. We
weaken Lester following HWRF intensity guidance through 72 hours,
then follow IVCN consensus on days 4 and 5.

FORECAST POSITIONS AND MAX WINDS

INIT 01/0900Z 18.2N 142.4W 95 KT 110 MPH
12H 01/1800Z 18.5N 144.3W 85 KT 100 MPH
24H 02/0600Z 19.1N 146.8W 80 KT 90 MPH
36H 02/1800Z 19.8N 149.3W 75 KT 85 MPH
48H 03/0600Z 20.5N 151.8W 70 KT 80 MPH
72H 04/0600Z 22.3N 157.1W 65 KT 75 MPH
96H 05/0600Z 24.5N 162.0W 60 KT 70 MPH
120H 06/0600Z 26.7N 165.9W 55 KT 65 MPH

$$
Forecaster Powell

[cycloneye]

HURRICANE LESTER DISCUSSION NUMBER 32
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP132016
500 AM HST THU SEP 01 2016

Lester's eye has re-emerged from cloud cover within the past hour
or so and deep convective cloud tops have begun to cool again, into
the -66 to -71 degree Celsius range as of 1330 UTC. However,
subjective Dvorak satellite intensity estimates from the analysis
centers continue to depict a slowly weakening system. These
estimates range from 5.0/90 kt from PHFO to 4.5/77 kt from JTWC and
SAB. UW-CIMSS provided an ADT of 4.8/85 kt. Given Lester's very
recent eye reappearance, continued good organization and CDO
symmetry with little or no shear deformation, we will assign 90 kt
for initial intensity. This represents slight weakening from last
time, but is at the high end of available intensity estimates.

Initial motion is 280/12 kt. However, some wobbling has
accompanied the eye re-emergence. The steering mechanism
remains unchanged as Lester continues to move generally westward
along the southern flank of a strong subtropical ridge. Upper
troughing expected to persist over and northwest of the main
Hawaiian Islands should allow Lester to gradually gain latitude
through the 5 day forecast period. Track guidance remains tightly
packed, depicting a gradual turn toward the west northwest through
day 2, then toward the northwest afterwards. UKMET and GFDL take
Lester over the main Hawaiian Islands, but all other commonly-used
guidance take Lester northeast of the Islands. HWRF is the right
outlier, while ECMWF and GFS lie within the right half of the
envelope. The forecast track closely follows the last one through 96
hours. The 120 hour point was adjusted to the northeast to keep the
total forecast track aligned with TVCN consensus. Like most of
the guidance, this track takes Lester northeast of the main
Hawaiian Islands. That said, it would take only a small leftward
shift in the track to directly and profoundly affect the Islands.
This possibility must be considered when making preparation plans
over the next couple of days.

All intensity guidance show Lester weakening through day 5, but at
different rates. Like last time, the global models want to keep
Lester relative strong, with GFS depicting a hurricane at day 5. In
contrast, SHIPS degrades Lester to a tropical storm at 48 hours. We
have followed IVCN consensus through 96 hours, then continued the
weakening trend after that as IVCN levels off.

FORECAST POSITIONS AND MAX WINDS

INIT 01/1500Z 18.4N 143.7W 90 KT 105 MPH
12H 02/0000Z 18.8N 145.6W 80 KT 90 MPH
24H 02/1200Z 19.4N 148.1W 75 KT 85 MPH
36H 03/0000Z 20.2N 150.6W 70 KT 80 MPH
48H 03/1200Z 21.0N 153.2W 65 KT 75 MPH
72H 04/1200Z 22.9N 158.4W 65 KT 75 MPH
96H 05/1200Z 25.0N 163.0W 60 KT 70 MPH
120H 06/1200Z 28.7N 166.7W 55 KT 65 MPH

$$
Forecaster Powell

[Ntxw]

Is Lester getting recon?

[talkon]

Looks like this is having an ERC right now.

[Yellow Evan]

Is Lester getting recon?

First mission at 6z.