EPAC: HILARY - Post-Tropical - Discussion

[Sciencerocks]

but if the nhc keeps it tropical then this allows it to be the first Califorina landfall since 1939.

[cycloneye]

 https://twitter.com/JimCantore/status/1693432521483047387

[wx98]

but if the nhc keeps it tropical then this allows it to be the first Califorina landfall since 1939.
https://imagizer.imageshack.com/img922/3191/A0NInT.gif

It already landfalled in Mexico and moved into California a few hours ago. There won’t be a landfall from that eddy because that isn’t the analyzed center. They should issue this advisory in a few minutes and probably let it go with a final one in the morning.

[Sciencerocks]

[Sciencerocks]

Well, wxman57 was right about this and this is probably going to move onshore soon!

[zhukm29]

Just putting this here to document a once-in-a-century event:

[Yellow Evan]

One could definitely at least argue we got our first California TS landfall since 1939 based on increasing evidence this moved offshore for a bit.

Looking at IR - I don't think Hilary meets the convective criteria for a TC any longer given how far the deep convection is removed from the center but I do feel it was potentially classifiable at 0z.

[Dar65]

I was going to comment early on this and I had a few questions and we’ll I guess I got my answers, but I have more questions.. I live in Compton and the center of Hilary passed right over me my first question is. Why did the forecasts never show this? Second, Why did it make a 90 degree turn just to come over my city and then make another 90 degree turn to go north. Lastly, am I really in the center of the storm noaa says I’m 1 mile away from it and I’m so confused

[dexterlabio]

Now the bigger challenge is for a tropical system to directly affect the San Francisco Bay Area.

[bob rulz]

I was going to comment early on this and I had a few questions and we’ll I guess I got my answers, but I have more questions.. I live in Compton and the center of Hilary passed right over me my first question is. Why did the forecasts never show this? Second, Why did it make a 90 degree turn just to come over my city and then make another 90 degree turn to go north. Lastly, am I really in the center of the storm noaa says I’m 1 mile away from it and I’m so confused

The "center" is very diffuse at this point. It wouldn't have a definable center like you would expect when you hear the word hurricane or tropical storm as it's essentially degraded into a post-tropical cyclone at this point, meaning it's very irregular in shape. Not sure about the track - that's something they'll probably analyze further in the post-storm report. Sometimes storms just don't go exactly where they're forecasted.

[wx98]

Looking at a long range radar loop, it seems like there was a reformation and “jump” of the *decaying* LLC from inland southern CA to the one over near the Long Beach/Los Angeles area. Would explain the shift in positioning at 3z. Don’t think you’d call that a California landfall though, but we shall see.

[snowpocalypse]

Is there cold enough air at high elevations anywhere this time of year to produce snow from this system?

[Dar65]

Looking at a long range radar loop, it seems like there was a reformation and “jump” of the *decaying* LLC from inland southern CA to the one over near the Long Beach/Los Angeles area. Would explain the shift in positioning at 3z. Don’t think you’d call that a California landfall though, but we shall see.

How did the storm reform?

[Socalhurcnegirl227]

Just had an earthquake, felt on LA westside. At the same time as a Tropical Storm. Incredible.

Yup this was the truly oddest event in my life time

[Iceresistance]

Just had an earthquake, felt on LA westside. At the same time as a Tropical Storm. Incredible.

Yup this was the truly oddest event in my life time

Apparently a 5.1, strongest of the year in California.

[cycloneye]

BULLETIN
Post-Tropical Cyclone Hilary Advisory Number 21
NWS Weather Prediction Center College Park MD EP092023
800 AM PDT Mon Aug 21 2023

...THE THREAT OF FLOODING AND GUSTY WINDS WILL CONTINUE WITH
HILARY TODAY IN THE INTERIOR WESTERN US...


SUMMARY OF 800 AM PDT...1500 UTC...INFORMATION
----------------------------------------------
LOCATION...41.6N 117.7W
ABOUT 115 MI...180 KM WNW OF ELKO NEVADA
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...NNE OR 15 DEGREES AT 24 MPH...39 KM/H
MINIMUM CENTRAL PRESSURE...1004 MB...29.65 INCHES


WATCHES AND WARNINGS
--------------------
Flood Watches are in effect for...
* Southern California
* Northwest Arizona
* Much of Nevada
* Southwest Utah
* Eastern Oregon
* Western and Central Idaho
* Far Southeast Washington

High Wind Warnings and Wind Advisories are in effect for...
* Northern and Central Nevada
* Western Utah
* Southern Idaho
* Southwest Montana


DISCUSSION AND OUTLOOK
----------------------
At 800 AM PDT (1500 UTC), the center of Post-Tropical Cyclone Hilary
was located near latitude 41.6 North, longitude 117.7 West. The
post-tropical cyclone is moving toward the north-northeast near 24
mph (39 km/h) and this motion is expected to continue before the
circulation dissipates later today.

Maximum sustained winds are near 35 mph (55 km/h) with higher gusts.
Hilary's circulation is expected to dissipate later today, but
gusty winds may continue for longer.

The estimated minimum central pressure is 1004 mb (29.65 inches).


HAZARDS AFFECTING LAND
----------------------
Key messages for Hilary can be found in the Tropical Cyclone
Discussion under AWIPS header MIATCDEP4 and WMO header WTPZ44 KNHC
and on the web at hurricanes.gov/text/MIATCDEP4.shtml.

RAINFALL: Rainfall will be diminishing across coastal Southern
California on Monday. Additional rainfall totals up to an inch are
possible. Hilary is expected to produce additional rainfall amounts
of 1 to 3 inches across portions of southeast California and
southern Nevada through Monday, with isolated storm total amounts
up to 12 inches. Continued flash and urban flooding is expected.

Across portions of Oregon and Idaho, rainfall totals of 1 to 3
inches with local maxima to 5 inches are expected through Tuesday
morning, resulting in localized, some significant, flash flooding.

A list of rainfall observations compiled by the NOAA Weather
Prediction Center for this storm can be found at:
available at www.wpc.ncep.noaa.gov/discussions/nfdscc4.html

WIND: Hilary is still expected to produce strong, gusty winds
today in Nevada, western Utah, southern Idaho, and southwest
Montana. The strongest gusts would be favored in high terrain,
passes, canyons, and summits.

SURF: Large swells will continue to affect portions of the Baja
California Peninsula and southern California through this morning.
These swells are likely to cause life-threatening surf and rip
current conditions. Please consult products from your local weather
office.


NEXT ADVISORY
-------------
Next complete advisory at 200 PM PDT.


Forecaster Lamers

[CronkPSU]

isn't it kind of common for typhoons to cause earthquakes around areas with major fault lines? Thought I read about a connection with an earthquake in Haiti and some typhoons in the Pacific Rim experiencing this

[Kingarabian]

Fortunate that there wasn't a typical +PDO/+PMM combo for Hilary to take advantage of. Could've lasted a little longer.

[CrazyC83]

I'd be curious to see the final damage total. I'd expect it to be in the billions.

[CrazyC83]

This is not official, but here is how I would analyze the best track of Hilary.

EP092023, HILARY, 29,
20230816, 0000, , LO, 10.8N, 99.8W, 30, 1007,
20230816, 0600, , TD, 11.7N, 100.8W, 30, 1005,
20230816, 1200, , TS, 12.6N, 102.4W, 35, 1002,
20230816, 1800, , TS, 13.1N, 103.7W, 40, 1000,
20230817, 0000, , TS, 13.7N, 104.8W, 50, 994,
20230817, 0600, , TS, 14.5N, 105.9W, 60, 988,
20230817, 1200, , HU, 15.2N, 107.2W, 75, 978,
20230817, 1800, , HU, 15.8N, 108.4W, 90, 963,
20230818, 0000, , HU, 16.4N, 109.5W, 110, 946,
20230818, 0600, , HU, 16.8N, 110.4W, 125, 934,
20230818, 1200, , HU, 17.4N, 111.1W, 115, 940,
20230818, 1800, , HU, 18.2N, 111.9W, 105, 947,
20230819, 0000, , HU, 19.2N, 112.4W, 105, 944,
20230819, 0600, , HU, 20.2N, 113.0W, 100, 942,
20230819, 1200, , HU, 21.5N, 113.3W, 95, 950,
20230819, 1800, , HU, 22.9N, 113.9W, 85, 958,
20230820, 0000, , HU, 24.3N, 114.3W, 75, 967,
20230820, 0600, , HU, 26.3N, 114.9W, 65, 974,
20230820, 1140, L, TS, 28.1N, 115.3W, 60, 982,
20230820, 1200, , TS, 28.2N, 115.4W, 60, 983,
20230820, 1730, L, TS, 29.9N, 115.8W, 50, 986,
20230820, 1800, , TS, 30.2N, 115.9W, 50, 987,
20230820, 2100, T, TS, 31.5N, 116.7W, 45, 990,
20230821, 0000, , TS, 33.2N, 117.7W, 40, 993,
20230821, 0120, L, TS, 33.8N, 118.1W, 40, 994,
20230821, 0600, , LO, 36.0N, 118.3W, 35, 999,
20230821, 1200, , LO, 40.3N, 118.0W, 30, 1003,

Some highlights:

* The early part of the track sees only minor changes, mainly to smooth out the track and intensities. Genesis is moved up 6 hours as a tropical depression (which it never was operationally).

* The rapid intensification on August 17-18 was likely even more rapid. The peak intensity is moved forward 6 hours, based on Dvorak estimates (ignoring the constraints) and the later Recon flight. The peak intensity remains 125 kt. The pressure of 934 mb assumes a lower pressure because the later Recon flights found somewhat lower than expected pressures for the analyzed intensities.

* After Recon arrived and all the way to landfall, the intensities are largely brought down by 5-10 kt. Recon generally found nothing remotely close to the analyzed intensities, but they had limited coverage of the storm due to distance to flight base and land (the strongest winds later in the life were either on land or in the Gulf of California). Hence, it is not brought all the way down to what Recon found.

* A first landfall is added on Cedros Island, west of Punta Eugenia. At that time, I estimate the winds were 60 kt.

* The official landfall on the Baja is moved slightly south and west, to Punta Baja. I believe the center only briefly went over land, then re-emerged over water within an hour or two. As a result, to help provide additional track information, I added a non-synoptic point at 2100Z.

* As the center I analyze as returning over water (based on later data), I estimate there was one last landfall, just west of the Orange-Los Angeles County Line in eastern Long Beach. At that time, I estimate the winds were 40 kt with a pressure of 994 mb (revised based on surface observations received), although the strongest winds were well east of the center.

* Both the time of decay (to a remnant low) and the time of complete dissipation are moved up 6 hours as well.