EPAC: HILARY - Post-Tropical - Discussion

[BobHarlem]

0 z gfs
Landfall roughly Laguna to Huntington Beach (pretty close to 18z run)



0z CMC, slight shift left

[CrazyC83]

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 9.1
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 18 AUG 2023 Time : 044022 UTC
Lat : 16:40:48 N Lon : 110:20:59 W


CI# /Pressure/ Vmax
6.7 / 924.0mb/132.2kt


Final T# Adj T# Raw T#
6.7 6.8 6.8

[zeehag]

in mazatlan under one of her outerbands..rain was not to hard, unfortunately it didnot wash the bird dirt off my car.. was a lovely rain. the thunder and lightning are west of me, and looks as if we may have some rain most of tonight.

[dexterlabio]

The possibility of a tropical storm watch in California is something we don't talk about often.

[MarioProtVI]

I think Hilary has an outside chance of briefly reaching Cat 5. Already up to 120 kt as of intermediate and they said RI is expected to continue. Recon later will be key if it’s as NHC has it.

[Kingarabian]

4 of the last 7 dvorak frames supported Cat.5.

[Cargill]

4 of the last 7 dvorak frames supported Cat.5.

Wow ... is this seriously out of the ordinary?

[CryHavoc]

4 of the last 7 dvorak frames supported Cat.5.

Wow ... is this seriously out of the ordinary?

The EPac is no stranger to Cat 5 hurricanes, including the strongest one in history (Patricia, 215mph sustained winds).

[Cargill]

I meant in terms of hurricanes that made landfall in Northern Mexico or Southern California.

[aspen]

IR presentation suggests we might be seeing an EWRC or eyewall meld about to take place.

[cycloneye]

Hurricane Hilary Discussion Number 8
NWS National Hurricane Center Miami FL EP092023
300 AM MDT Fri Aug 18 2023

Hilary's satellite presentation has continued to improve overnight,
with a solid ring of cold cloud tops surrounding a warming eye.
TAFB and SAB provided consensus Dvorak estimates of T6.0/115 kt
while objective estimates are a bit higher, between 125-135 kt.
The advisory intensity is therefore set at 125 kt as a blend
of the various estimates. Hilary has rapidly intensified by a
remarkable 65 kt over the past 24 hours. The hurricane remains
large, and the initial wind radii have been adjusted based on a
recent ASCAT-C pass. An Air Force Reserve Hurricane Hunter
aircraft is scheduled to investigate Hilary around midday and
should provide a more precise estimate of the hurricane's intensity.

The hurricane continues to move toward the west-northwest, or 300/11
kt. However, with mid-tropospheric high pressure nudging eastward
from the Rocky Mountains into the Central Plains, and a cut-off low
off the California coast, Hilary is expected to turn northwestward
very soon and then turn northward and begin accelerating by 48
hours. The track guidance is more tightly clustered than usual
during the first 72 hours of the forecast, and therefore there is
relatively high confidence in the NHC track forecast, which is
essentially unchanged from the previous advisory. Since Hilary's
forecast track parallels the coast from the central Baja California
peninsula northward to southern California, it is still nearly
impossible to predict an exact landfall location, not to mention
that Hilary's exact landfall probably won't make much difference
when it comes to the expected hazards and impacts in the region.

Hilary could strengthen a little more during the next 12 hours or
so. However, once hurricanes reach major hurricane strength, they
are prone to fluctuations in intensity, particularly if an eyewall
replacement begins. In addition, oceanic heat content will be
dropping significantly in 24-36 hours, and it's likely that Hilary's
large wind field will mix up cooler water ahead of the arrival of
the center. This colder water, as well as potential interaction
with the terrain of the Baja California peninsula, is expected to
induce faster weakening over the weekend, with Hilary likely to drop
below hurricane intensity some time on Sunday. Due to its
accelerating motion in 2 to 3 days, Hilary is still expected to be
producing tropical-storm-force winds when it reaches southern
California. The surface circulation is likely to dissipate soon
after moving into California, but a day 4 remnant low point is still
shown over the western U.S. for continuity purposes.


KEY MESSAGES:

1. Heavy rainfall associated with Hilary may produce areas of flash
flooding and result in landslides over portions of the Baja
California Peninsula from late today into late Sunday. Rainfall
impacts from Hilary within the Southwestern United States are
expected to peak this weekend into Monday. Flash, urban, and arroyo
flooding is expected with the potential for significant impacts.

2. The threat of hurricane-force wind impacts is increasing along
the west-central coast of the Baja California Peninsula, where a
hurricane watch is in effect. Tropical storm conditions are
expected to begin across the southern portion of the Baja California
Peninsula later today and then spread northward through the weekend.

3. The threat of significant wind impacts continues to increase for
the northern portions of the Baja California Peninsula and the
Southwestern United States, especially in areas of mountainous
terrain. Although it is too soon to determine the location and
magnitude of these impacts, interests in these areas should monitor
the progress of Hilary and updates to the forecast. Watches could
be issued for portions of this area, including along the southern
California coast, later today.

4. Large swells from Hilary will spread northward along the coast
of southwestern Mexico and the Baja California Peninsula. These
swells will reach the Gulf of California and northern portions of
the Baja California Peninsula later this weekend.


FORECAST POSITIONS AND MAX WINDS

INIT 18/0900Z 17.2N 110.8W 125 KT 145 MPH
12H 18/1800Z 18.3N 112.0W 130 KT 150 MPH
24H 19/0600Z 20.2N 113.2W 120 KT 140 MPH
36H 19/1800Z 22.4N 114.0W 105 KT 120 MPH
48H 20/0600Z 25.3N 114.7W 85 KT 100 MPH
60H 20/1800Z 28.7N 115.6W 65 KT 75 MPH
72H 21/0600Z 32.9N 116.7W 50 KT 60 MPH...INLAND
96H 22/0600Z 43.6N 117.3W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 23/0600Z...DISSIPATED

$$
Forecaster Berg

[GCANE]

6Z GFS now has a cutoff low developing out of the trof to Hilary's NW on approach to landfall

[GCANE]

IR presentation suggests we might be seeing an EWRC or eyewall meld about to take place.

Water-Vapor Satellite imagery at the lower levels does seem to show the eye drying out IMHO.
A sign of a possible EWRC forthcoming.

[GCANE]

To me, this is the most concerning issue with Hilary.
South CA is a tinderbox.
Anything away from a rain area could fan a wildfire.
Just saw this in Maui.

 https://twitter.com/JimCantore/status/1692503615527616622

[cycloneye]

BULLETIN
Hurricane Hilary Intermediate Advisory Number 8A
NWS National Hurricane Center Miami FL EP092023
600 AM MDT Fri Aug 18 2023

...HILARY REMAINS A LARGE AND POWERFUL CATEGORY 4 HURRICANE...
...SIGNIFICANT FLOODING IMPACTS POSSIBLE ACROSS PORTIONS OF THE
BAJA CALIFORNIA PENINSULA AND THE SOUTHWESTERN UNITED STATES...


SUMMARY OF 600 AM MDT...1200 UTC...INFORMATION
----------------------------------------------
LOCATION...17.3N 111.0W
ABOUT 100 MI...165 KM S OF SOCORRO ISLAND
ABOUT 400 MI...640 KM S OF CABO SAN LUCAS MEXICO
MAXIMUM SUSTAINED WINDS...145 MPH...230 KM/H
PRESENT MOVEMENT...WNW OR 300 DEGREES AT 13 MPH...20 KM/H
MINIMUM CENTRAL PRESSURE...942 MB...27.82 INCHES

[cycloneye]

 https://twitter.com/JimCantore/status/1692495616423649482

[BobHarlem]

Las Vegas AFD:

All eyes remain on Hurricane Hilary and it`s impending impact on
the Southwestern US. Guidance remains tightly clustered showing
Hilary`s center of circulation lifting north along the Baja
Peninsula Saturday and Sunday and emerging into far southern
California as weak tropical storm or depression by early Monday.
To say this is an unusual weather pattern would be a huge
understatement, as similar tropical systems impacting the
southwest US are rare in our modern record, namely Nora in 1997,
and Kathleen in 1976 were most recent similar storms to have their
remnant circulation pass directly through our forecast area.
Norbert in 2014 caused significant flood impacts to the area even
while the remnant storm remained well offshore of the Mexico
coast.

Regardless of the exact track Hilary takes, a tremendous moisture
flux will enter the region through the Gulf of California and
stream north over the weekend. Precipitable water values at this
time will climb towards record territory, reaching 1.75"+ in Las
Vegas and over 2" in the lower Colorado River Valley.
Additionally, increasing south or southeasterly low level wind
fields are expected as whats left of Hilary lifts northward,
particularly Sunday and Monday, resulting in a strong orographic
component in the higher terrain working to further squeeze out
moisture content in the area. Guidance remains insistent on
widespread rainfall totals of 2-4" across our western zones,
including most of the western Mojave Desert (Yucca Valley, Joshua
Tree, Twentynine Palms, Landers, Barstow, Baker) northward into
Inyo County including Death Valley and the Owens Valley. Some
ensembles are also suggesting more than 2 inches of rain in the
Las Vegas Valley, though ensemble means suggest closer to 1-2
inch storm totals for the metro area. Rainfall totals reaching
even half this much will cause significant issues for some of our
area, and it`s likely some major flood issues will evolve for the
areas that get hardest hit over the weekend and into next week.

The WPC Excessive Rainfall Outlook has this risk well covered,
with a moderate risk of excessive rainfall advertised on Day 2
for the Morongo Basin region in Southern San Bernardino County,
with a widespread Slight Risk. This moderate expands to include
most of the Mojave Desert on Day 3 along with a small patch of
High Risk in the Morongo Basin. We believe this is the fist time
a High Risk of excessive rainfall has been delineated by the WPC
in our forecast area.

All this to say, the expectation remains that periods of very
heavy rain continue to be expected as Hilary`s remains lift
through the region Saturday-Monday. Timing of the periods of
heaviest precipitation remains a bit uncertain, but should tend
to spread from south to north over the coming days. In addition to
the wet conditions and potential flood risk, deep moisture
entrenched over the region will keep temperatures unseasonably
cool, with the possibility of record low maximum temperatures
Sunday and Monday for much of the region.

Moisture will begin to thin out as Hilary becomes a thing of the
past by Tuesday onward. However, deep moisture will remain across
the area beneath a south or southeasterly flow aloft, suggesting
at least low-grade storm activity will continue into early next
week.

[cycloneye]

Plane has departed from Keesler base. It will be close to Hilary around 1 PM EDT.

[Socalhurcnegirl227]

To me, this is the most concerning issue with Hilary.
South CA is a tinderbox.
Anything away from a rain area could fan a wildfire.
Just saw this in Maui.

https://twitter.com/JimCantore/status/1692503615527616622

No not everywhere here is a tinderbox. My husband works for the usfs, fuel moistures in many spots are still decent. Were alot less dry than we were last august.

[SconnieCane]

Hilda

Hil da beast.

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