CPAC: LINDA - Post-Tropical

[Kingarabian]

Convection dissipating. Doubt it's anywhere near hurricane strength now. Very odd NHC classification of "post-tropical" with 40 kt winds as it nears Hawaii. May be more of a remnant low with 25-30 kts given the cooler water in its path. Good news for Hawaii. We have a number of clients there.

What do you think about models that still show impacts though?
12z Euro still wants to give Kauai some TS force winds. 12Z HWRF has 50mph sustained and 60mph gusts for Maui. 12z HMON the same as the HWRF but for Oahu. CMC continues to insist this will affect Maui or the Big Island.

This stuff all looks minor but remember Iselle in 2014? It hit Puna Big Island with 60mph winds causing nearly 200-300million dollars over a country county of 32000 people. All thanks to Hawaii's 3rd world infrastructure.

[galaxy401]

Convection dissipating. Doubt it's anywhere near hurricane strength now. Very odd NHC classification of "post-tropical" with 40 kt winds as it nears Hawaii. May be more of a remnant low with 25-30 kts given the cooler water in its path. Good news for Hawaii. We have a number of clients there.

What do you think about models that still show impacts though?
12z Euro still wants to give Kauai some TS force winds. 12Z HWRF has 50mph sustained and 60mph gusts for Maui. 12z HMON the same as the HWRF but for Oahu. CMC continues to insist this will affect Maui or the Big Island.

This stuff all looks minor but remember Iselle in 2014? It hit Puna Big Island with 60mph winds causing nearly 200-300million dollars over a country county of 32000 people. All thanks to Hawaii's 3rd world infrastructure.

Not a Pro Met but I highly doubt Linda will be anywhere close to Iselle. It's already much weaker and doesn't have El Nino conditions to carry it.

[Kingarabian]

Convection dissipating. Doubt it's anywhere near hurricane strength now. Very odd NHC classification of "post-tropical" with 40 kt winds as it nears Hawaii. May be more of a remnant low with 25-30 kts given the cooler water in its path. Good news for Hawaii. We have a number of clients there.

What do you think about models that still show impacts though?
12z Euro still wants to give Kauai some TS force winds. 12Z HWRF has 50mph sustained and 60mph gusts for Maui. 12z HMON the same as the HWRF but for Oahu. CMC continues to insist this will affect Maui or the Big Island.

This stuff all looks minor but remember Iselle in 2014? It hit Puna Big Island with 60mph winds causing nearly 200-300million dollars over a country county of 32000 people. All thanks to Hawaii's 3rd world infrastructure.

Not a Pro Met but I highly doubt Linda will be anywhere close to Iselle. It's already much weaker and doesn't have El Nino conditions to carry it.

Yeah I'm just wondering because that's what the two hurricane models we use are starting to show. Douglas from last year showed that if shear permits, convection can refire regardless of the base state being favorable or not.

[Sciencerocks]

[cycloneye]

Tropical Storm Linda Discussion Number 39
NWS National Hurricane Center Miami FL EP122021
1100 AM HST Thu Aug 19 2021

Linda continues to come unhinged. Dry and stable air has wrapped
almost completely into the cyclone's circulation, as indicated by
the low-level stratocumulus cloud field that now primarily
characterizes the system. Linda has now lacked organized deep
convection for nearly 6 h. A blend of the T- and CI- numbers from
the latest subjective Dvorak intensity estimates suggest that the
cyclone's initial intensity has decreased to 45 kt. Cool SSTs of
24-25 C and dry, stable air should prevent any significant deep
convection from returning over the next couple of days. Therefore,
Linda could be declared post-tropical by tonight. The low will reach
warmer waters in a few days. However, by that time, strong
southwesterly shear within a dry environment should inhibit
regeneration of the cyclone, and the low should should open into a
trough early next week. The latest NHC intensity forecast remains
near the HCCA and IVCN consensus.

Over the past several hours Linda has moved almost due west with a
12 h motion of about 275/15 kt. Steered by a low- mid-level ridge to
its north, a general westward motion is expected until the system
dissipates. The latest NHC track forecast is little changed from the
previous one, and is close to the tightly packed track guidance.

Linda is crossing into the central Pacific basin, and this will be
the final NHC advisory on this system. Future information on Linda
can be found in Forecast/Advisories issued by the Central Pacific
Hurricane Center beginning at 0300 UTC under AWIPS header HFOTCMCP3
and WMO header WTPA23 PHFO.

FORECAST POSITIONS AND MAX WINDS

INIT 19/2100Z 19.7N 139.5W 45 KT 50 MPH
12H 20/0600Z 19.9N 141.8W 35 KT 40 MPH...POST-TROPICAL
24H 20/1800Z 20.2N 144.7W 30 KT 35 MPH...POST-TROP/REMNT LOW
36H 21/0600Z 20.4N 147.2W 30 KT 35 MPH...POST-TROP/REMNT LOW
48H 21/1800Z 20.8N 149.5W 30 KT 35 MPH...POST-TROP/REMNT LOW
60H 22/0600Z 21.1N 151.7W 30 KT 35 MPH...POST-TROP/REMNT LOW
72H 22/1800Z 21.5N 153.9W 30 KT 35 MPH...POST-TROP/REMNT LOW
96H 23/1800Z 22.0N 158.4W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 24/1800Z...DISSIPATED

$$
Forecaster Latto

[Kingarabian]

For the next 48 hours, looks like it's following the CMC track and will have a hard time getting to or above 20N while it stays this shallow.


In about 24 hours it should start to move back over warm.

Hour 60 is when the shear kicks in so it could have have about 30-36 hours to attempt and re-develop. If it does this, around hour 72 it'll gain more latitude before it gets sheared off again.

[Yellow Evan]

Linda is non-convective right now and still hasn’t hit shear. I don’t see the threat.

[Kingarabian]

Wonder if it can pull an Epsilon with shear forecast to be low for the next 48-60 hours.

[Kingarabian]

Hope the mid shear comes back:

[Kingarabian]

TXPN21 KNES 200008
TCSCNP

A. 12E (LINDA)

B. 19/2330Z

C. 19.8N

D. 140.2W

E. THREE/GOES-W

F. T2.0/3.0

G. IR/EIR/VIS

H. REMARKS...SYSTEM IS DEVOID OF CONVECTION. MET IS 3.0 BASED ON RAPID
WEAKENING OVER THE LAST 24 HOURS. PT IS 2.5. FT IS BASED ON CONSTRAINTS
LIMITING CHANGES IN T-NUMBER TO 1.5 OVER 12 HOURS.

I. ADDL POSITIONS

NIL


...TURK

[Yellow Evan]

Wonder if it can pull an Epsilon with shear forecast to be low for the next 48-60 hours.

There’s no upper trough to provide that sort of bulk column instability to sustain convection like you see near the Azores. Coupling Index’s here are much lower.

[cycloneye]

Tropical Storm Linda Discussion Number 40
NWS Central Pacific Hurricane Center Honolulu HI EP122021
500 PM HST Thu Aug 19 2021

Linda continues to slowly weaken as evident by the lack of deep
convection associated with the system. A well defined low and mid
level cloud swirl is all that remains. The latest subjective Dvorak
estimates suggest that the cyclone's initial intensity has decreased
to around 40 kt.

Cooler SSTs and a drier and more stable air mass out ahead of the
system should prevent any significant deep convection from returning
over the next couple of days. Therefore, Linda could be declared a
post-tropical low sometime tonight. The low will reach warmer waters
in a couple of days but strong southwesterly shear should inhibit
regeneration of the cyclone, and the low should open up into a
trough early next week. The latest CPHC intensity forecast remains
near the HCCA and IVCN consensus.

Over the past several hours, Linda has been moving slightly north
of due west at around 15 kt. Linda will continue to be steered by
a low-mid level ridge to its north. Thus a general westward motion
is expected for the system until is dissipates in about 5 days. The
latest CPHC track forecast is little changed from the previous one,
and is within to the tightly packed track guidance.


FORECAST POSITIONS AND MAX WINDS

INIT 20/0300Z 19.9N 141.1W 40 KT 45 MPH
12H 20/1200Z 20.2N 143.4W 35 KT 40 MPH...POST-TROPICAL
24H 21/0000Z 20.5N 146.2W 30 KT 35 MPH...POST-TROP/REMNT LOW
36H 21/1200Z 20.9N 148.4W 30 KT 35 MPH...POST-TROP/REMNT LOW
48H 22/0000Z 21.2N 150.8W 30 KT 35 MPH...POST-TROP/REMNT LOW
60H 22/1200Z 21.5N 153.1W 30 KT 35 MPH...POST-TROP/REMNT LOW
72H 23/0000Z 21.8N 155.4W 30 KT 35 MPH...POST-TROP/REMNT LOW
96H 24/0000Z 22.2N 160.2W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 25/0000Z...DISSIPATED

$$
Forecaster Burke

[Kingarabian]

Issued: 8/19/2021, 9:00 PM HST

Synopsis

Breezy easterly trade wind conditions will persist through Friday night with clouds and showers favoring windward and mauka locations. Although a few showers may spill over into our dry leeward areas, accumulations should remain limited through early Saturday. The latest forecast from the Central Pacific Hurricane Center depicts Tropical Storm Linda approaching and moving through the area from east to west Sunday through Monday as a post- tropical remnant low. Impacts associated with this remnant low will highly depend on its exact track as it moves into the area. While a track passing just north of the islands would lead to lighter winds and limit rainfall accumulations, a track through or south of any of the islands would result in a wetter and windier pattern. A return to a more typical trade wind pattern is expected Tuesday through midweek.

Discussion

A mostly dry and stable trade wind pattern is anticipated through Saturday with clouds and showers favoring windward and mauka locations (best shower chances overnight through the morning periods). Breezy easterly trades will hold through Friday, then back to the north over the eastern end of the state and northeast for the western end Saturday through Saturday night as the remnant low associated with former Hurricane Linda approaches from the east.

The latest forecast from the Central Pacific Hurricane Center has the remnant low over or around the eastern end of the state Sunday, then the western end Sunday night through Monday. As stated above, impacts associated with this feature will highly depend on the track as it moves through. If the low passes the islands to the north, expect lighter winds and limited rainfall accumulations. A track through or south of any of the islands would result in a wetter and windier pattern. Flash flooding and damaging winds can't be ruled out if this latter scenario were to unfold. Confidence in the details will continue to increase as we head into the weekend. For the latest information on Linda, refer to the Central Pacific Hurricane Center.

Will come down to the wall of shear.

[cycloneye]

BULLETIN
Tropical Storm Linda Advisory Number 41
NWS Central Pacific Hurricane Center Honolulu HI EP122021
1100 PM HST Thu Aug 19 2021

...LINDA BARELY HANGING ON AS A TROPICAL CYCLONE...


SUMMARY OF 1100 PM HST...0900 UTC...INFORMATION
-----------------------------------------------
LOCATION...19.9N 142.5W
ABOUT 820 MI...1315 KM E OF HILO HAWAII
ABOUT 1000 MI...1610 KM E OF HONOLULU HAWAII
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...W OR 270 DEGREES AT 17 MPH...28 KM/H
MINIMUM CENTRAL PRESSURE...1006 MB...29.71 INCHES


WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.


DISCUSSION AND OUTLOOK
----------------------
At 1100 PM HST (0900 UTC), the center of Tropical Storm Linda was
located near latitude 19.9 North, longitude 142.5 West. Linda is
moving toward the west near 17 mph (28 km/h), and this general
motion is expected to continue for the next few days, with some
slowing in forward speed.

Maximum sustained winds are near 45 mph (75 km/h) with higher gusts.
Linda is expected to become post-tropical on Friday, with slow
weakening forecast during the next 48 hours.

Tropical-storm-force winds extend outward up to 80 miles (130 km)
from the center.

The estimated minimum central pressure is 1006 mb (29.71 inches).


HAZARDS AFFECTING LAND
----------------------
SURF: Swells generated by Linda will affect east facing shores
of the main Hawaiian Islands over the next couple of days. Please
consult products from the National Weather Service's Honolulu
Forecast Office.


NEXT ADVISORY
-------------
Next complete advisory at 500 AM HST.

$$
Forecaster Birchard

[Sciencerocks]

[cycloneye]

Post-Tropical Cyclone Linda Discussion Number 42
NWS Central Pacific Hurricane Center Honolulu HI EP122021
500 AM HST Fri Aug 20 2021

Linda's time as a tropical cyclone has come to an end. Infrared and
VIIRS day-night satellite imagery depict an elongating low cloud
swirl, and deep convection has been absent over the center for
nearly 24 hours, thus Linda is deemed to be post-tropical. The
initial intensity estimate of 35 kt for this advisory remains
heavily influenced by a recent scatterometer pass that indicated
winds to 40 kt north of the center.

The initial motion estimate is 280/15 kt, with Linda being steered
by a persistent low- to mid-level ridge to the north. Tightly-
clustered track guidance indicates that the ridge will continue to
drive the post-tropical remains of Linda toward the west, with a
slight reduction in forward speed tonight and Saturday. The guidance
has trended southward over the last couple of days, and the official
forecast indicates that remnants of Linda will impact portions of
the main Hawaiian Islands Sunday and Monday, in line with the
corrected consensus guidance HCCA, and the GEFS mean.

Compared to the recent rapid weakening, a relatively slow rate of
decay of the wind field is expected over the next couple of days.
As the system gradually spins down, gale force winds north of the
center will be slow to diminish, due to the gradient between the
high to the north and the remnant low. Some sporadic deep convection
may also occur, but the combined effects of dry air in the mid- and
upper-levels and increasing vertical wind shear will prevent
regeneration into a tropical cyclone, and lead to system dissipation
by day 4. This is supported by the reliable global models, as well
as the intensity consensus IVCN.

This is the last advisory issued by the Central Pacific Hurricane
Center on Linda. Future information on this system can be found in
forecasts issued by the National Weather Service in Honolulu, on
the web at http://weather.gov/hfo.


FORECAST POSITIONS AND MAX WINDS

INIT 20/1500Z 20.3N 144.0W 35 KT 40 MPH...POST-TROPICAL
12H 21/0000Z 20.5N 146.1W 35 KT 40 MPH...POST-TROPICAL
24H 21/1200Z 20.7N 148.4W 35 KT 40 MPH...POST-TROPICAL
36H 22/0000Z 20.9N 150.5W 35 KT 40 MPH...POST-TROPICAL
48H 22/1200Z 21.0N 152.4W 35 KT 40 MPH...POST-TROPICAL
60H 23/0000Z 21.1N 154.3W 30 KT 35 MPH...POST-TROP/REMNT LOW
72H 23/1200Z 21.3N 156.9W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 24/1200Z...DISSIPATED

$$
Forecaster Birchard

[Sciencerocks]

[Kingarabian]

Will be going over 26C waters soon.


Deep layer shear jumps to 30kts soon. But the most damaging type of shear, mid shear, remains near 10kts.

[Yellow Evan]

Maybe the plug shouldn’t have been pulled…

[Kingarabian]

Gale warnings up for the entire state.