August 2021: Major Hurricane Ida/SE Louisiana Landfall

[don]

While the eventual location of coc will definitely go a long ways in getting a better handle on eventual track. Modeling doesn't need a 'center' to pick up on a potential change in steering currents....

Otherwise just a day or so ago it was a Tampico ish solution no matter where the center formed with the projected ridging...

Yep, I was gonna say this. Models have gotten a lot better with TC track than they were 10+ years ago.While having a center is important and can result in a change in track.It tends to be an exception more often than the norm these days that a track drastically changes once a center has formed.80-90% of the time storm tracks don't change drastically once TC genesis has occurred.(keep in mind im referring more to Homebrew storms though, as long tracked storms are a different story.) By Thursday we should have more confidence in regards to track.

[Scott747]

While the eventual location of coc will definitely go a long ways in getting a better handle on eventual track. Modeling doesn't need a 'center' to pick up on a potential change in steering currents....

Otherwise just a day or so ago it was a Tampico ish solution no matter where the center formed with the projected ridging...

Yep, I was gonna say this. Models have gotten a lot better with TC track than they were 10+ years ago.While having a center is important and can result in a change in track.It tends to be an exception more often than the norm these days that a track drastically changes once a center has formed.80-90% of the time storm tracks don't change drastically once TC genesis has occurred.(keep in mind im referring more to Homebrew storms though, as long tracked storms are a different story.) By Thursday we should have more confidence in regards to track.

Correct. Not to mention once recon starts flying and ingesting data (which should begin by Friday) the track really does consolidate much of the time.

Getting back to the model runs... There is a battle on the 18z GFS between the southern and northern part of the axis. There has been subtle hints for a few runs now but nothing like what the Euro and experimental model had, but it's definitely there now. Looks like it's in part to the ULL you had mentioned earlier. Good pick up!

[tireman4]

Meanwhile, back at the ranch...


000
FXUS64 KHGX 242021
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
321 PM CDT Tue Aug 24 2021


.SHORT TERM [Tonight through Wednesday Night]...
Isolated showers are beginning to pop up mainly in the coastal
counties as we begin to see the signs of the upper-level ridge
weakening. Coverage will remain sparse at most as satellite
derived PW values remain on the low side around 1.6"-1.7". As
upper-level ridging continues to weaken and expand northward, low-
level moisture will filter back into the area from the east. PW
values will increase to 1.9"-2.1" by Wednesday morning. With a few
shortwaves wrapping around an upper-level high over the Central
Plains, this presents a more favorable set up for afternoon
showers and thunderstorms. Coverage of convection will lean
towards being scattered, especially in the late afternoon/evening
hours. The latest CAMs are in agreement on a cluster of
thunderstorms moving in from the east during this timeframe, but
uncertainty remains on how long they hold together as they track
across Southeast Texas. Moisture will linger along the coast going
into Wednesday night along with another shortwave passing
through, so keeping in chance PoPs (30-40%) going into Thursday.

It`s late August in Southeast Texas, so we know it`s hot...but
exactly how hot will it be? Well 850mb temperatures will remain in
the 21-22 degrees Celsius range, so highs in the mid-to-upper 90s
are still supported. This means above normal temperatures will
continue through at least Wednesday. The big question will be if the
added low-level moisture and relatively light winds (5-7 knots) will
be enough to cross the Heat Advisory threshold for Wednesday...it`ll
be very close, and we`re talking by about only a degree or two. The
general consensus is that heat index values will reach 106-108 for
Wednesday, which is right on the edge of our criteria. Either way,
it`s going to be hot so if you have anything planned outdoors please
continue to practice heat safety. Wear light-colored/loose-fit
clothing, take plenty of breaks from direct sunlight, drink plenty
of water, and look before you lock. Additionally, Wednesday is an
Ozone Action Day, so members of sensitive groups should limit their
time outdoors tomorrow as conditions will be favorable for high
amounts of ozone pollution.

Batiste


.LONG TERM [Thursday through Tuesday]...
Looking at an increasingly wet pattern late in the week with daily
thunderstorm chances with diurnal heating...occasionally modulated
by short wave energy in E to W upper flow...and southern flank of
upper ridge. Expect greater coverage of the storms
southern/coastal areas...more scattered well inland...so POPs
reflect this along with the diurnal cycle.

As we get to the weekend...all eyes will be on the SW Gulf where
it is likely a tropical cyclone will either be emerging off the
Yucatan or perhaps forming over that area. From there higher than
average uncertainty on where the cyclone would track. Models have
generally trended north today...with more tracking toward and into
Texas...fewer advertising the more southern track into Mexico that
was fairly common yesterday. 12Z run of the European Model has
come in with an even more drastic turn north...heading toward
Louisiana. Bottom line...track and forecast will remain changeable
and uncertain until system forms which is not expected until
Friday at the earliest and possibly over the weekend. Will also be
highly dependent on nature of the ridge to the north. Will need
to monitor the forecast carefully next few days. Potential for all
hazards depending on how the system evolves and tracks...but too
early to be specific. Regardless of exact track most likely will
see elevated tides...seas and heavy rains early next week at a
minimum. Stay tuned.

Reilly

&&

.AVIATION [18Z TAF Issuance]...
Scattered cumulus clouds continue to encompass much of the area
around 4,000-5,000 ft. Expecting VFR conditions to prevail for the
TAF period. Light southwesterly winds will shift over to light
southeasterly winds over the next couple of hours. Winds will
become light and variable overnight as the pressure gradient
weakens. There are some hints of another round of isolated pockets
of patchy fog and low clouds, but not expecting these form a
solid cloud deck. SGR stands the best chance of experiencing these
conditions once again after 10z. Winds will remain on the light
side heading into Wednesday morning with a gradual shift towards
southeasterly winds by the afternoon hours. The latest CAMs
indicate isolated showers/thunderstorms will develop Wednesday
afternoon after 21z, but positioning of the convection is too iffy
this far out to throw in any VCSH/VCTS in this TAF package.

Batiste

&&

.MARINE...
Really benign winds and seas in the short term with light winds
through the rest of the week into the weekend. Winds mainly
onshore and around or below 10 knots through Saturday. Onshore
flow then begins to increase with strengthening gradient between
ridge to the NE and possible tropical cyclone emerging from the
Yucatan Peninsula out over the SW Gulf. For Sunday and Monday may
well have rapidly deteriorating more hazardous conditions as long
period swell emanates out from the cyclone and the storm tracks
NW toward the Texas coast potentially. Details on this potential
tropical system still uncertain...as haven`t seen any development
yet but vitally important mariners stay tuned to the forecast. For
this package leaned heavily on the WNA model...based on GFS wind
fields...which brings 12+ foot waves into the coastal waters
Sunday night and Monday. Stay tuned.

Reilly

&&



.PRELIMINARY POINT TEMPS/POPS...

College Station (CLL) 76 97 77 96 76 / 0 20 10 40 20
Houston (IAH) 78 98 78 95 77 / 10 40 20 60 40
Galveston (GLS) 82 92 81 90 81 / 10 30 40 70 50

&&

.HGX WATCHES/WARNINGS/ADVISORIES...

TX...None.
GM...None.

&&

$$

[weatherguy425]

While the eventual location of coc will definitely go a long ways in getting a better handle on eventual track. Modeling doesn't need a 'center' to pick up on a potential change in steering currents....

Otherwise just a day or so ago it was a Tampico ish solution no matter where the center formed with the projected ridging...

Yep, I was gonna say this. Models have gotten a lot better with TC track than they were 10+ years ago.While having a center is important and can result in a change in track.It tends to be an exception more often than the norm these days that a track drastically changes once a center has formed.80-90% of the time storm tracks don't change drastically once TC genesis has occurred.(keep in mind im referring more to Homebrew storms though, as long tracked storms are a different story.) By Thursday we should have more confidence in regards to track.

Correct. Not to mention once recon starts flying and ingesting data (which should begin by Friday) the track really does consolidate much of the time.

Getting back to the model runs... There is a battle on the 18z GFS between the southern and northern part of the axis. There has been subtle hints for a few runs now but nothing like what the Euro and experimental model had, but it's definitely there now. Looks like it's in part to the ULL you had mentioned earlier. Good pick up!

Like you said, still a battle. But, trend on the GFS has been to make northern lobe dominant like the ICON, CMC and ECWMF. I think that’s when ridge strength and orientation will become very important.

[Scott747]

This run is likely to be further up the coast on a smoother movement instead of the bobble motion on the 12z and much stronger.

[Scott747]

This is definitely going to be a run to take a deep breath and realize that it's still very much a complicated forecast....

[TexasBreeze]

No kidding on the stronger part of it! Cpv17 I wouldn't look at the 18z if I were you!!!

[don]

Hopefully its just a fluke run.

[vci_guy2003]

What strength does the 18z show?

[Scott747]

948 into Matagorda Bay on the 1st.

Have to dig in to the model a little more to tell if it's setting up dual outflow channels which helps the rapid deepening.

[AtascocitaWX]

And it looks like it stalls... or am i tripping?

[Stratton20]

Holy crap thats a concerning run by the GFS.. Cat 4 into matagorda vay plus a very slow drift inland.. Hoping this is just a one time run...

[Scott747]

It's quite large as well and a characteristic of these CAG influenced systems.

Even with a hit down by Matagorda it would put hurricane force gusts and sustained winds as far n as coastal Brazoria and Galveston counties and ts force winds across the metro area s of 10.

Again it's just one model run and almost certain to change...

[AtascocitaWX]

And it looks like it stalls... or am i tripping?

No its just a slow mover.

[Stratton20]

Scott747 yeah juat one run, but it does show the potential for something really powerful

[JWL]

That REALLY needs to not happen….Carla with huge increase in structures/population

[tireman4]

As these next days start to roll on by, remember, this may change from model run to model run. This is the time for my annual PSA. There are amazing pro and amateur Mets on this board and we thank them for coming in and taking the time to spend with us. They will answer your questions, but remember, they are busy too. If you do not get an answer right away, please be patient. Also, take this time ( as always during Hurricane season), to go over your plans and have your kits stocked and ready to go. Double and triple-check your supplies. This is always a good motto to have, whether we have threatening conditions or mild skies.

[Stormlover2020]

I’ll go out on a limb and say corpus to sw la right now, I don’t see it being central la but I would put it at 10 percent odds

[AtascocitaWX]

And that windfield(IKE) is large on this run, That will be a mean strong storm surge for Galveston Bay and Kemah.

[Cpv17]

No kidding on the stronger part of it! Cpv17 I wouldn't look at the 18z if I were you!!!

Yeah that’s a big hard no for me. I don’t want anything to do with that run.