August 2021: Major Hurricane Ida/SE Louisiana Landfall

[Scott747]

Hurricane models are up and running for 99l

[Andrew]

GEFS Ensembles are still all over the place

[Stratton20]

Jeez what a forecasting nightmare..

[Cpv17]

GEFS Ensembles are still all over the place

Louisiana to Mexico. That clears things up nicely

[Scott747]

GEFS Ensembles are still all over the place

And by a small majority they continue to favor the southern edge of guidance.

Won't be surprised with a swing back w with the Euro. Can't count the times where it led the way with a sizable shift with other models following only to swing back.

Will say I'll be curious what the experimental model shows. It was the first one to show the eastern solution.

*edit*

18z experimental models shifts even further E towards New Orleans.

[Rip76]

GEFS Ensembles are still all over the place

Louisiana to Mexico. That clears things up nicely

Haha

[sambucol]

Is there a recon scheduled for 99L?

[Scott747]

Is there a recon scheduled for 99L?

Not yet. Probably won't be a flight till Friday.

[Andrew]

UKMET still shows S Texas

[Andrew]

00Z ECMWF around the Sabine Pass/Lake Charles region.

[Andrew]

00Z HWRF Vermillion Bay

[Stratton20]

00z Euro has shifted back to the west, right on the tx/lousiana border

[DoctorMu]

0z ICON - odd man out for now.

[Andrew]

0z ICON - odd man out for now.

UKMET is a lot further south and more in line with the GEFS (and more trustworthy than the ICON) but the consensus has shifted towards the TX/LA border today

[Stratton20]

I think we are going to see a shift back to the west again with “todays runs” because the Euro shifted back west some because the ridge builds back in late and forces the storm more toward the tx/la border, but I could be wrong though of course

[Andrew]

I think we are going to see a shift back to the west again with “todays runs” because the Euro shifted back west some because the ridge builds back in late and forces the storm more toward the tx/la border, but I could be wrong though of course

Ridging continues to weaken through the middle of next week according to the ECMWF so it could be a case of how far west does the system get before turning north.

[djmike]

Wow. Modeling started with Mexico and recently now Vermilion Bay La? Thats quite the range. So it would be safe to say Mexico to the Bahamas are at play here? Lol

[cperk]

The 6oz GFS shifted slightly east of the Texas/Louisiana border.

[TexasBreeze]

Looks like the hot sunny solution may end up winning out for our area at this rate! At this shift rate it could go to Florida in the end! We will see.

[tireman4]

000
FXUS64 KHGX 250921
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
421 AM CDT Wed Aug 25 2021

.SHORT TERM [through Thursday Night]...

Hot weather with increasing chances of precipitation are the main
weather story today. Upper-level ridge remains centered to our north-
northwest, keeping our region under an east to northeast flow aloft.
Several shortwaves embedded within the flow aloft will continue to
move into the region today. Upper-level forcing, daytime heating and
low-level convergence due to the seabreeze will allow for scattered
showers and thunderstorms later today into early evening. Severe
weather is not expected; however gusty winds will be possible with
any strong storms. Forecast soundings display a classic inverted-v
signature, suggesting the potential for some isolated strong winds.
Highs will range from the mid to upper 90s. We`ll be close to our
Heat Advisory criteria with heat index values from 103 to 107
degrees this afternoon.

Unsettled conditions continue on Thursday. Upper-level disturbances
continue to ride along the southern edge of the high pressure while
a surface trough moves across the Upper TX coast. This trough will
act as the focus area for moisture and warm air being advected into
the region. Off and on scattered showers and thunderstorms are
expected throughout the day. Increasing cloud cover and
precipitation chances should keep high temperatures mainly in the
low to mid 90s. 05

.LONG TERM [Friday through Wednesday]...

The strong ridge of high pressure that has been over Texas the past
few days will be eroding and sliding eastward over the weekend
allowing for an influx of moisture into the region (PWATs up to 2.25
inches on Friday). A shortwave will be moving through the area on
Friday, which combined with the increase in moisture available in
the atmosphere will lead to scattered showers and thunderstorms
through the evening. Precipitation coverage on Saturday will be less
compared to Friday with the lack of any upper level support, but
daytime heating should be enough to initiate scattered showers and
thunderstorms. However, on Saturday all focus will be on the
southern Gulf for potential tropical development.

Currently, the NHC is monitoring a disturbance (Invest 99L) in the
southern Caribbean that has a High chance (70%) of tropical cyclone
formation within the next five days as it moves into the western
Caribbean. There is still a lot of uncertainty with how strong and
where this system will go. This is unlike with Grace, which had high
confidence in its track due to a strong high pressure over the
northern Gulf guiding it almost due west across the Yucatan
Peninsula. For this system, high pressure will exist over SE CONUS
and a trough will be digging down across the Northern Rockies this
weekend. The exact location, strength, and timing of these features
will play a large roll in the track of Invest 99L and we just do not
have that information right now with much confidence.

So what do we know? - We know that there is potential that a
tropical cyclone will be moving through the western Gulf through the
weekend and into early next week. Potential impacts will be
increased wave heights and rip currents as early as this weekend
with the potential of heavy rainfall early to mid week next week.

When will we know more? - It remains just too early for any
specifics on track and intensity of this system. By the end of
this week we should have a better clue on the upper level pattern
going into the weekend. And once this system actually forms, if it
ever does, then model guidance will hopefully get a better handle
on its track. Exactly where the center of rotation forms plays an
important part in a storms evolution, so once that develops and
guidance has a known starting point, the ending point becomes
clearer.

What should you do? - Keeping monitoring the forecast from us and
from the NHC for any updates on this system. If monitoring
model cycles on social media, do not put too much stock into
individual model runs. There will be many changes in these from
run to run and from model to model in the next few days as the
details remain in flux. Review your hurricane preparedness plans
and kits to make sure they are up to date. We are entering the
climatological peak of the Atlantic hurricane season, so making
sure those are complete won`t hurt even if you don`t need them
with this potential system.

Fowler

&&

.MARINE...

Light onshore winds and low seas will continue through Friday. A
weak upper level disturbance will move through the area on Friday
increasing coverage of showers and thunderstorms, so there may be
locally gusty winds and higher seas near stronger thunderstorms.
Winds and seas begin to increase late Saturday ahead of a potential
tropical cyclone developing the in the southern Gulf. Sunday night
through Monday has the potential to have strong winds, high seas of
9 to 12 ft, and heavy rainfall. A high risk of strong rip currents
begins as early as Sunday. This forecast is highly dependent on
whether this system develops and on its exact track, so please
continue to monitor the forecast in the coming days. Conditions
should slowly improve midweek next week.

Fowler

&&

.PREV DISCUSSION /Issued 1138 PM CDT Tue Aug 24 2021/...

.AVIATION...
Debris clouds from earlier convection in La and east Tx will thin
out overnight. VFR conditions should mostly prevail thru the
period with the exception of in/near any convection. Moisture
availability increases Wed, and with daytime heating expect sct
shra/tstms to develop across the area. Forecast soundings show an
inverted-v profile which would indicate the potential for some
gusty winds in the stronger cells into the evening hours. 47

&&

.PRELIMINARY POINT TEMPS/POPS...

College Station (CLL) 97 76 95 75 92 / 20 10 50 10 40
Houston (IAH) 98 77 95 76 91 / 30 20 70 40 70
Galveston (GLS) 92 80 90 80 89 / 30 30 70 60 60

&&

.HGX WATCHES/WARNINGS/ADVISORIES...

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

&&

$$