EPAC: DOUGLAS - Remnants

[HurricaneEnzo]

Welp the core has completely passed Hawaii with no landfall. Did the mountainous terrain have some sort of effect on its track or was this just a miss by the models?

[wxman57]

Recon FL winds were barely hurricane strength. SFMR winds higher than FL winds are suspect. Winds could have dropped below hurricane strength at the surface. Dropsonde data indicate about 50-55 kts in SW quadrant and 65-70 kts in the SE quadrant. No report from NE quadrant lately. Hanging on to low-end Cat 1 strength.

[TheStormExpert]

Trying to get a hurricane or tropical storm to make landfall on the Hawaiian Islands from the East is like threading a needle. Iniki was different because it came from the south and west. Fortunately the worst of Douglas spared the island chain but hopefully nothing else comes and gives them a scare the rest of the season.

[Kingarabian]

Well that just about wraps it up for Douglas for the main Hawaiian islands and we (or at least myself) can move on. Appreciate everyone's input, dialogue, and the great conversations in the past week in regards to Douglas.

[Yellow Evan]

Its collapsing now but that was an unexpectedly fun storm to track.

[wxman57]

Here's a 21Z sat pic from when CPHC was classifying Douglas as a 70 kt hurricane. Hmmm...

[cycloneye]

Tropical Storm Douglas Discussion Number 31
NWS Central Pacific Hurricane Center Honolulu HI EP082020
500 PM HST Mon Jul 27 2020

The satellite presentation for Douglas shows an exposed low level
circulation center (LLCC), with deep convection limited to the
north quadrant. Subjective Dvorak satellite intensity estimates
range from 3.5/55 kt, from SAB and HFO, to 4.0/65 kt from JTWC.
UW-CIMSS ADT is 58 kt. Given these estimates and the continued
degradation noted in satellite imagery, Douglas is assigned an
initial intensity of 60 kt, making this system a tropical storm once
again. The degraded satellite imagery is driven by continued 20 to
25 kt southwesterly wind shear which will remain a factor in this
system's future for the next 36 to 48 hours. Initial motion is
270/15, representing a persistent 12 hour westerly motion noted
since the LLCC became exposed this morning. However since fix time,
a slight northward component has been detected.

Douglas continues to be steered by a deep ridge to its north and
the expectation is for this system to continue on a west to west
northwest track through the remainder of its life. Wind shear is
forecast to decrease somewhat after 48 hours, but global models in
particular give Douglas no chance for redevelopment. The forecast
track for Douglas is quite close to the previous one, falling
within the southern third of the guidance envelope through 48 hours
between HWRF and HMNI. This envelope is rather tight through 72
hours, after which Douglas is forecast to dissipate.

FORECAST POSITIONS AND MAX WINDS

INIT 28/0300Z 22.9N 163.3W 60 KT 70 MPH
12H 28/1200Z 23.2N 165.8W 50 KT 60 MPH
24H 29/0000Z 23.5N 169.3W 45 KT 50 MPH
36H 29/1200Z 23.9N 173.3W 45 KT 50 MPH
48H 30/0000Z 24.2N 177.5W 40 KT 45 MPH
60H 30/1200Z 24.8N 178.3E 35 KT 40 MPH
72H 31/0000Z 25.6N 174.2E 30 KT 35 MPH...POST-TROP/REMNT LOW
96H 01/0000Z...DISSIPATED

$$
Forecaster Powell

[Hammy]

Trying to get a hurricane or tropical storm to make landfall on the Hawaiian Islands from the East is like threading a needle. Iniki was different because it came from the south and west. Fortunately the worst of Douglas spared the island chain but hopefully nothing else comes and gives them a scare the rest of the season.

I have to wonder if topography is part of it, we have a bunch of (relatively) small islands with high terrain, lined up almost parallel to the direction that storms from the east would track, and it seemed like it got close and sort of bounced north a bit each time.

[bob rulz]

Lane fell apart the moment it reached the latitude of the Big Island. Obviously I have no way of knowing if the mountains on the Big Island had an effect but I thought it was interesting at the time.

I absolutely think the topography of the Hawaiian Islands affects approaching storms significantly and makes landfalls on the islands as potent storms difficult.

[HurricaneEnzo]

Lane fell apart the moment it reached the latitude of the Big Island. Obviously I have no way of knowing if the mountains on the Big Island had an effect but I thought it was interesting at the time.

I absolutely think the topography of the Hawaiian Islands affects approaching storms significantly and makes landfalls on the islands as potent storms difficult.

Yeah I definitely believe land interaction in some instances can have that affect on storms. I remember something similar with Irma as it raked Cuba. Looked like it was coming in for landing and 'bounced' away at the last minute. This it kinda bounced down Cuba for a while before finally making landfall. IDK maybe it was just a coincidence but it seem like the land interaction caused it.

[Kingarabian]

It's like a naked swirl now not sure how it's a TS.

[1900hurricane]

 https://twitter.com/1900hurricane/status/1288235924703281153

[Astromanía]

ACE count?

[TheStormExpert]

Definitely a close call for Hawaii!

 https://twitter.com/nwshonolulu/status/1288297469072281602

[cycloneye]

Post-Tropical Cyclone Douglas Discussion Number 37...CORRECTED
NWS Central Pacific Hurricane Center Honolulu HI EP082020
452 AM HST Wed Jul 29 2020

A cluster of thunderstorms north of Douglas' center is producing an
impressive amount of lightning this morning, but is not indicative
of system reorganization. While these thunderstorms are indeed
associated with Douglas' deteriorating circulation, they are removed
from the center, and will soon be sheared away by persistent
southerly vertical wind shear. Satellite imagery shows the exposed
low-level circulation center becoming increasingly elongated, while
an earlier ASCAT pass indicated little in the way of westerly flow
in the southern semicircle. Douglas has degenerated into a post-
tropical remnant low (and may already be an open wave) with maximum
winds on the north side estimated to be near 30 kt.

With Douglas' initial motion vector of 275/20 kt, associated
hazards have moved west of the Papahanaumokuakea Marine National
Monument, and the Tropical Storm Warning has been discontinued. A
strong low-level ridge to the north will steer Douglas rapidly
westward, with the remnant low expected to cross the International
Date Line later today. As the remnant low rounds the ridge, it is
expected to gain some latitude over the next 24 hours or so before
dissipating, in line with global model guidance and the previous
forecast.

This is the last advisory issued by the Central Pacific Hurricane
Center on Douglas. Additional information on this system can be
found in the High Seas Forecasts issued by the National Weather
Service in Honolulu under AWIPS header HFOHSFNP and WMO header
FZPN40 PHFO.


FORECAST POSITIONS AND MAX WINDS

INIT 29/1500Z 24.7N 175.4W 30 KT 35 MPH...POST-TROP/REMNT LOW
12H 30/0000Z 25.0N 178.6W 30 KT 35 MPH...POST-TROP/REMNT LOW
24H 30/1200Z 25.9N 177.2E 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 31/0000Z...DISSIPATED

$$
Forecaster Birchard

[NXStumpy_Robothing]

Of course, right after it gets declared as a post-tropical/remnant system, it decides to do this.

[CrazyC83]

Of course, right after it gets declared as a post-tropical/remnant system, it decides to do this.
https://i.imgur.com/lBsu3P5.jpg

No circulation though. Is JMA monitoring it as an invest?

[CrazyC83]

The posts in this forum are NOT official forecasts and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or STORM2K. For official information, please refer to products from the NHC and NWS.

Here would be my BT for Douglas:

EP082020, DOUGLAS, 41,
20200720, 0000, , LO, 14.6N, 118.8W, 30, 1011,
20200720, 0600, , LO, 14.2N, 119.2W, 30, 1011,
20200720, 1200, , TD, 13.9N, 119.5W, 30, 1010,
20200720, 1800, , TS, 13.6N, 119.9W, 35, 1008,
20200721, 0000, , TS, 13.3N, 120.9W, 45, 1004,
20200721, 0600, , TS, 13.0N, 122.2W, 50, 1002,
20200721, 1200, , TS, 12.6N, 123.6W, 55, 1000,
20200721, 1800, , TS, 12.2N, 124.8W, 55, 1001,
20200722, 0000, , TS, 12.1N, 126.1W, 60, 999,
20200722, 0600, , HU, 11.8N, 127.5W, 65, 996,
20200722, 1200, , HU, 11.7N, 128.9W, 70, 993,
20200722, 1800, , HU, 11.9N, 130.3W, 80, 986,
20200723, 0000, , HU, 12.3N, 131.9W, 90, 977,
20200723, 0600, , HU, 12.8N, 133.3W, 105, 967,
20200723, 1200, , HU, 13.3N, 135.0W, 105, 966,
20200723, 1800, , HU, 13.8N, 136.5W, 115, 955,
20200724, 0000, , HU, 14.6N, 138.0W, 120, 950,
20200724, 0600, , HU, 15.3N, 139.5W, 110, 958,
20200724, 1200, , HU, 16.1N, 141.1W, 105, 963,
20200724, 1800, , HU, 16.7N, 142.7W, 100, 968,
20200725, 0000, , HU, 17.5N, 144.3W, 100, 969,
20200725, 0600, , HU, 18.2N, 145.9W, 95, 971,
20200725, 1200, , HU, 18.7N, 147.6W, 90, 977,
20200725, 1800, , HU, 19.1N, 149.2W, 85, 981,
20200726, 0000, , HU, 19.7N, 150.7W, 80, 983,
20200726, 0600, , HU, 20.1N, 152.1W, 80, 984,
20200726, 1200, , HU, 20.5N, 153.6W, 80, 985,
20200726, 1800, , HU, 21.0N, 155.1W, 80, 987,
20200727, 0000, , HU, 21.7N, 156.6W, 80, 988,
20200727, 0600, , HU, 22.3N, 158.1W, 85, 985,
20200727, 1200, , HU, 22.6N, 159.7W, 80, 987,
20200727, 1800, , HU, 22.8N, 161.4W, 70, 993,
20200728, 0000, , TS, 23.0N, 162.8W, 55, 999,
20200728, 0600, , TS, 23.2N, 164.2W, 45, 1004,
20200728, 1200, , TS, 23.8N, 165.7W, 40, 1007,
20200728, 1800, , TS, 24.2N, 167.7W, 35, 1009,
20200729, 0000, , TD, 24.4N, 169.9W, 30, 1011,
20200729, 0600, , TD, 24.6N, 172.1W, 30, 1011,
20200729, 1200, , TD, 24.6N, 174.4W, 30, 1011,
20200729, 1800, , TD, 24.8N, 176.5W, 30, 1012,
20200730, 0000, , LO, 25.1N, 178.3W, 25, 1013,