August 2021: Major Hurricane Ida/SE Louisiana Landfall

[Stratton20]

00z ICON has trended toward the Euro

[don]

Yep

[Cpv17]

Man that Icon run kills me lol puts me in the right front quadrant of the eye.

[cperk]

The 6Z GFS shifted about 200 miles north making landfall around the Texas/Mexico border heading NW into Texas.

[TexasBreeze]

Interesting models this morning for sure! Euro kept it's track and the 6z GFS shows close to the border with another system afterwards.

[Scott747]

6z GFS has back to back systems about a week apart for N. Mex and lower Texas coast.

GFS is still resolving the 2nd system but it's the one that has me a little more concerned with a potentially better environment.

Either way looks like a busy two weeks for interests in the Western Gulf.

[Cromagnum]

Interesting models this morning for sure! Euro kept it's track and the 6z GFS shows close to the border with another system afterwards.

Gross.

[Scott747]

An active tropical wave is moving across the eastern Caribbean.
Its axis is along 69W and extends from Dominican Republic to
western Venezuela. The wave is producing scattered showers and
thunderstorms, particularly from 10N-15N between 61W-73W. This
convective activity is affecting the Windward Islands. The wave
is also helping to induce scattered moderate to strong convection
over western Venezuela. A broad area of low pressure is expected
to form along the wave axis over the southwestern Caribbean Sea
later this week. Thereafter, environmental conditions are forecast
to be favorable for gradual development, and a tropical depression
could form by the end of the week while the system moves west-
northwestward to northwestward over the northwestern Caribbean
Sea.

Visually - https://cdn.star.nesdis.noaa.gov/GOES16 ... 0x1000.jpg

[Andrew]

I still think the most likely scenario for next week's system (the first one) is into Mexico. Upper-level ridging will remain in pretty strong control across much of the SE United States including most of Texas. There is an upper-level trough that is expected to track through the Northern Plains during the middle of next so that is something will need to continue to monitor, but overall I suspect/hope upper-level ridging will remain in control enough to keep this a South Texas/Mexico storm. Remember, the ECMWF has not been as reliable of a model this year (and last year) and with Henri, it really did a poor job of recognizing the strength of ridging to its north. Still, something we need to continue to monitor over the next couple of days as a lot can change.

[don]

6Z GFS with a pretty big shift north into the valley/north Mexico, 0Z Euro still into Matagorda.The Euro ensembles have shifted further north with a lot more showing Texas now fwiw.

[Stormlover2020]

Andrew all depends where center forms.

[jerryh421]

How soon do we think they will tag it as an invest? Today?

[don]

From Wxman57

I think there's at least a 90% chance we'll have at least a TS in the southern Gulf by Sunday/Monday. Threat may be farther north than Grace. Definitely not ruling out Texas. Only real question is whether it will be Ida or Julian. System in the open Atlantic may develop first and head out to sea.

[djmike]

How soon do we think they will tag it as an invest? Today?

Im thinking today possibly tomorrow for sure.

[Stratton20]

06 GFS has shifted North by a good margin, maybe the GFS is beginning to cave into the Euro solution

[jasons2k]

Here is latest from Jeff with a good explanation of why the southern solution may win out:

A tropical wave moving through the central Caribbean Sea will arrive in the western Caribbean later this week.

Chances for tropical cyclone formation are increasing over the western Caribbean Sea late this week into this weekend. Overall it appears to be a fairly complex setup for formation with the incoming tropical wave likely interacting with a northward extension of the central American monsoon trough. Deterministic and ensemble global model guidance continues to show robust probabilities of tropical cyclone formation over the western Caribbean Sea and NHC currently has chances now at 60% for days 3-5.

There remains a fair amounts of uncertainty as to where the system may track and how strong it could become. The GFS and CMC are showing more of a WNW track from the western Caribbean into the Bay of Campeche and then landfall in eastern MX, although the very latest 06Z GFS run has shifted north toward the TX/MX border. The EURO and ICON models are much further to the north and indicate landfalls along the TX coast. It is important in these types of situations to look at the multi-model ensemble guidance which tends to give the range of possibilities at hand. Ensembles from the EURO, GFS, and CMC indicate a wide range of possible track solutions from the eastern coast of MX to SW LA. Of interest is that many of the EURO ensemble members are south of the deterministic run and many of the CMC members are well north of its deterministic run. The GFS members are generally in and around its deterministic run. This tends to indicate that the EURO is likely a bit far north and the CMC too far south.

The overall steering pattern over the western Gulf of Mexico will be undergoing changes over the next 48-72 hours as blocking high pressure over much of the US Gulf coast weakens and shifts northward (our local rain chances will be increasing). By this weekend into early next week, this high weakens even more and a break in the sub-tropical ridge develops over the southern plains as a trough sweeps across the northern plains. High pressure will build over the SE US ahead of the northern plains trough and this feature along with the passage of the trough over the northern plains will likely be the key to the long term and ultimate track of the system. A stronger ridge over the SE US would tend to favor a more southern track toward eastern MX, while a weaker ridge would likely result in a more NW motion. Additionally, where the low level center forms over the western Caribbean is important as a low forming closer to central America is likely to take a further south track than a low forming further to the N or NW.

There remains lots of uncertainty and there will likely be a fair degree of uncertainty until late this week or early this weekend when a surface low forms.

At this point it is too soon to know what if any impacts can be expected along the TX coast. Moisture levels will be increasing starting later today and expect daily scattered showers and thunderstorms Wednesday into the weekend. Models point toward a good push of moisture toward the TX coast this weekend and the threat of heavy rainfall increasing. Additionally, seas will be building across the western Gulf starting early this weekend and this will likely result in wave run-up on the beaches and some coastal flooding.

Persons along the TX coast are urged to monitor forecasts closely over the next several days.

[weatherguy425]

Here is latest from Jeff with a good explanation of why the southern solution may win out:

A tropical wave moving through the central Caribbean Sea will arrive in the western Caribbean later this week.

Chances for tropical cyclone formation are increasing over the western Caribbean Sea late this week into this weekend. Overall it appears to be a fairly complex setup for formation with the incoming tropical wave likely interacting with a northward extension of the central American monsoon trough. Deterministic and ensemble global model guidance continues to show robust probabilities of tropical cyclone formation over the western Caribbean Sea and NHC currently has chances now at 60% for days 3-5.

There remains a fair amounts of uncertainty as to where the system may track and how strong it could become. The GFS and CMC are showing more of a WNW track from the western Caribbean into the Bay of Campeche and then landfall in eastern MX, although the very latest 06Z GFS run has shifted north toward the TX/MX border. The EURO and ICON models are much further to the north and indicate landfalls along the TX coast. It is important in these types of situations to look at the multi-model ensemble guidance which tends to give the range of possibilities at hand. Ensembles from the EURO, GFS, and CMC indicate a wide range of possible track solutions from the eastern coast of MX to SW LA. Of interest is that many of the EURO ensemble members are south of the deterministic run and many of the CMC members are well north of its deterministic run. The GFS members are generally in and around its deterministic run. This tends to indicate that the EURO is likely a bit far north and the CMC too far south.

The overall steering pattern over the western Gulf of Mexico will be undergoing changes over the next 48-72 hours as blocking high pressure over much of the US Gulf coast weakens and shifts northward (our local rain chances will be increasing). By this weekend into early next week, this high weakens even more and a break in the sub-tropical ridge develops over the southern plains as a trough sweeps across the northern plains. High pressure will build over the SE US ahead of the northern plains trough and this feature along with the passage of the trough over the northern plains will likely be the key to the long term and ultimate track of the system. A stronger ridge over the SE US would tend to favor a more southern track toward eastern MX, while a weaker ridge would likely result in a more NW motion. Additionally, where the low level center forms over the western Caribbean is important as a low forming closer to central America is likely to take a further south track than a low forming further to the N or NW.

There remains lots of uncertainty and there will likely be a fair degree of uncertainty until late this week or early this weekend when a surface low forms.

At this point it is too soon to know what if any impacts can be expected along the TX coast. Moisture levels will be increasing starting later today and expect daily scattered showers and thunderstorms Wednesday into the weekend. Models point toward a good push of moisture toward the TX coast this weekend and the threat of heavy rainfall increasing. Additionally, seas will be building across the western Gulf starting early this weekend and this will likely result in wave run-up on the beaches and some coastal flooding.

Persons along the TX coast are urged to monitor forecasts closely over the next several days.

It'll be interesting to watch trends over the next couple days and several model runs. More and more of the EPS ensemble members are creeping northward. The operational run may be a bit north of the favored solution, but not by too much. Canadian ensembles is well north of the latest operational. run. As troughing enters the northern United States (what may weaken western flank of ridge) trends and observations will become even more important.

[Cromagnum]

There is way more spin with this area north of PR than down where the area of interest is, and it is moving W/SW. I'm sure its an upper level low, but it's interesting to see it.

[tireman4]

000
FXUS64 KHGX 241203
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
703 AM CDT Tue Aug 24 2021

.AVIATION [12Z TAF Issuance]...

High pressure continues bringing VFR conditions through the
period. Some light ground fog is possible in low lying areas
(possibly impacting SGR, CXO, and UTS) through sunrise, and again
overnight tonight. South to southeasterly winds will persist
through the day, becoming light and variable overnight tonight.
Scattered clouds between 3500 and 5000 ft will develop during the
afternoon. Some isolated showers will develop along the coast
during the late afternoon and evening possible moving near GLS and
LBX. These will be very isolated showers, so kept VCSH out of the
TAFs.

Fowler

&&

.PREV DISCUSSION /Issued 327 AM CDT Tue Aug 24 2021/...

.SHORT TERM [Through Wednesday]...

A slightly similar weather pattern is expected across southeast
TX today. Ridging aloft remains anchored across the
central/southern Plains, resulting in east to northeast flow
aloft. Daytime heating and a slightly uncapped environment should
support some spotty showers along the sea breeze later this
afternoon. Coverage should be pretty minimal, and mainly along the
coastal counties. Kept highs close to the 90th percentile of
climatology, that is, from the mid to upper 90s. This is 1 to 5
degrees above normal.

Several shortwaves will be moving along the southern periphery of
the high pressure tonight through the rest of the week,
potentially firing off isolated to scattered precipitation. The
first shortwave/vort max located over the LA coast will possibly
bring scattered activity late this evening as it moves
west-southwest. Better precipitation chances will occur along the
coast and near/offhsore waters. Showers and storms will continue
to move into the region and expand in coverage as we head into
peak daytime heating on Wednesday. A broad area of theta-e will
advect south-southwest along with increasing dynamics provided by
a subtle inverted trough, resulting in isolated to scattered
activity during the day. Highs will once again range in the mid to
upper 90s.

05


.LONG TERM [Wednesday Night Through Monday Night]...

As the upper-level ridge moves north-northwest, deeper low to mid
level moisture returns to the region with PWATs increasing near 2+
inches after Thursday. Coupled with an inverted trough, the region
will see the beginning of unsettled conditions into the weekend. As
the upper level wave begins to interact with the sfc trough in
the afternoon hours, more unstable air begins to move into the
region which will increase the likelihood of showers and storms
inland on Friday. In terms of temperatures, cloud cover and
precipitation chances will keep readings near seasonal Thursday
through Saturday.

As we head into next weekend, the upper ridge to our north will
begin to break down while the Bermuda high pushes west into the
eastern CONUS. NHC continues to monitor the potential for
tropical cyclone development in the next 5 days near/at the
western Caribbean and/or the Bay Campeche. Deterministic and
ensemble members have been in decent agreement developing a
tropical cyclone near/over southwestern Gulf late this weekend
into early next week. However, uncertainty arises regarding its
track as it will potentially depend on the strength of the upper
level ridge over the southeastern CONUS. Therefore, there is still
a high level of uncertainty on where and when this system will
form, so continue to monitor the latest forecast from our office
and the NHC. Regardless of whether this system develops or not,
tropical moisture will increase through the period. Have added
PoPs as NBM guidance suggests with 40 to 60 percent through the
end of the period.

05


.MARINE...

High pressure will remain dominant through the next couple of
days continuing the mostly clear skies, light onshore flow, and
low seas we`ve been enjoying recently. This high pressure weakens
by the end of the week and retreats northwards increasing
precipitation chances through the weekend. There will be a low
pressure system developing in the southern Gulf late in the
weekend. While there is still a fair amount of uncertainty with
the progression of this system, we can at least expect an increase
in wave heights and rip currents as early as Sunday and continue
through Tuesday. Continue to monitor the forecast through the
coming days for any changes in this forecast.

Fowler

&&

.PRELIMINARY POINT TEMPS/POPS...

College Station (CLL) 97 76 98 77 95 / 0 10 20 10 40
Houston (IAH) 97 78 98 78 94 / 0 10 30 20 60
Galveston (GLS) 91 82 92 81 90 / 20 20 30 40 70

&&

.HGX WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

[don]

12z ICON into Port Aransas. I'm concerned about the inverted trough moving in from the Bahamas which could help to pull the storm further north. That could be what some of the models are seeing with the further north solutions.