September 2021: Hurricane Nicholas

General Weather Discussions and Analysis
Stormlover2020
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Cpv17 wrote: Sun Sep 12, 2021 1:08 pm
Stormlover2020 wrote: Sun Sep 12, 2021 1:06 pm
Cpv17 wrote: Sun Sep 12, 2021 1:01 pm Not expecting much from this here in the Wharton/El Campo area. Hoping I can at least get an inch or two from it.


You serious lol
Yeah. With the current track, the center would pass about 30 miles east of me. I’d be on the dry side. Hoping it shifts a lil west.

U Will tons of bands
Cpv17
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Stormlover2020 wrote: Sun Sep 12, 2021 1:10 pm
Cpv17 wrote: Sun Sep 12, 2021 1:08 pm
Stormlover2020 wrote: Sun Sep 12, 2021 1:06 pm



You serious lol
Yeah. With the current track, the center would pass about 30 miles east of me. I’d be on the dry side. Hoping it shifts a lil west.

U Will tons of bands
I think the western side will be fighting some dry air so I’m expecting most of the convection to be on the eastern side.
Stratton20
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Interesting to note that it looks like a LLC has been found farther NW than originally anticipated
Samantha550
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djmike wrote: Sun Sep 12, 2021 12:56 pm Do yall think Jefferson county will eventually be included on any TS watch/warning?
Donald at Lake Charles NWS said tonight or tomorrow morning at the latest.
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Ptarmigan
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sambucol wrote: Sun Sep 12, 2021 12:13 pm
Ptarmigan wrote: Sun Sep 12, 2021 12:06 pm GFS has hurricane on Tuesday.
https://i.imgur.com/A3CL69G.png

HWRF has a hurricane and making landfall on Texas.
https://i.imgur.com/UjOup3F.png
979? That’s a high end category 2
979 millibars is usually Category 1. It depends on size and ambient pressure. I have see 979 millibars in tropical storms, mainly in the West Pacific.
Scott747
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12z Euro looks a little off early on. Ends up going in s of Brownsville and up through the King Ranch.
TexasBreeze
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The Euro looks rough to the west of here so far... Cpv17! Close to Bryan CS too Dr. Mu.
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Belmer
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Euro showing 60 inches in Fayette County... ok.

15-20 inches to our west/southwest counties. 5-12 inches around Houston with the lower amounts being further east you are (opposite of GFS).
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Belmer wrote: Sun Sep 12, 2021 1:49 pm Euro showing 60 inches in Fayette County... ok.

15-20 inches to our west/southwest counties. 5-12 inches around Houston with the lower amounts being further east you are (opposite of GFS).
When will you know if these numbers verify?
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Belmer
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jabcwb2 wrote: Sun Sep 12, 2021 1:57 pm When will you know if these numbers verify?
I'd like to see a dominant low-level circulation develop that we can track. I see a vigorous eddy that could be it. Further NW than where NHC has it and did line up with the Euro a bit better as far as position. Euro has been more of the outlier on the extreme rainfall totals. 00z runs tonight should provide better clarity... I hope.
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jabcwb2 wrote: Sun Sep 12, 2021 1:57 pm
Belmer wrote: Sun Sep 12, 2021 1:49 pm Euro showing 60 inches in Fayette County... ok.

15-20 inches to our west/southwest counties. 5-12 inches around Houston with the lower amounts being further east you are (opposite of GFS).
When will you know if these numbers verify? I wasn't expecting that much rain in the Tomball area!
jabcwb2
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Belmer wrote: Sun Sep 12, 2021 2:03 pm
jabcwb2 wrote: Sun Sep 12, 2021 1:57 pm When will you know if these numbers verify?
I'd like to see a dominant low-level circulation develop that we can track. I see a vigorous eddy that could be it. Further NW than where NHC has it and did line up with the Euro a bit better as far as position. Euro has been more of the outlier on the extreme rainfall totals. 00z runs tonight should provide better clarity... I hope.
Thank you!!
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Ptarmigan
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Belmer wrote: Sun Sep 12, 2021 1:49 pm Euro showing 60 inches in Fayette County... ok.

15-20 inches to our west/southwest counties. 5-12 inches around Houston with the lower amounts being further east you are (opposite of GFS).
Image

61 inches of rain is Harvey rainfall total. The other forecast models I have seen do not have any amounts anywhere near. They are usually between 12 to 20 inches.

It looks like a core rain event could occur as I looked at hourly models, in which the bulk of the rain is at night. If it did happen, it will lead to severe flooding. Central Texas is very prone to flooding.

Too early to tell again.
Last edited by Ptarmigan on Sun Sep 12, 2021 2:13 pm, edited 1 time in total.
Cromagnum
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Euro has lost its mind.

Image
davidiowx
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Those are some pretty extreme numbers in the Euro. That is a bad trend if it keeps it up tonight into tomorrow. I think Harvey dumped 60” or so just to the NE of Houston with most of the city in the 40” range over 4 days or so. Unbelievable output by the Euro. Hope it’s an outlier.

Several pages back, this was brought up, the Euro continuously showed those high totals run after run. I don’t recall, was the Euro showing that prior to Harvey being a hurricane? Or was it after it was undergoing RI that the Euro started showing those totals?
Stratton20
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What the heck ! My jaw dropped looking at this euro run
Last edited by Stratton20 on Sun Sep 12, 2021 2:27 pm, edited 1 time in total.
Goomba
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davidiowx wrote: Sun Sep 12, 2021 2:11 pm Those are some pretty extreme numbers in the Euro. That is a bad trend if it keeps it up tonight into tomorrow. I think Harvey dumped 60” or so just to the NE of Houston with most of the city in the 40” range over 4 days or so. Unbelievable output by the Euro. Hope it’s an outlier.

Several pages back, this was brought up, the Euro continuously showed those high totals run after run. I don’t recall, was the Euro showing that prior to Harvey being a hurricane? Or was it after it was undergoing RI that the Euro started showing those totals?
60.58" in the Golden Triangle (Nederland) from Harvey.

Hopefully, that run of the Euro is a fluke.
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Ptarmigan
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Goomba wrote: Sun Sep 12, 2021 2:15 pm
davidiowx wrote: Sun Sep 12, 2021 2:11 pm Those are some pretty extreme numbers in the Euro. That is a bad trend if it keeps it up tonight into tomorrow. I think Harvey dumped 60” or so just to the NE of Houston with most of the city in the 40” range over 4 days or so. Unbelievable output by the Euro. Hope it’s an outlier.

Several pages back, this was brought up, the Euro continuously showed those high totals run after run. I don’t recall, was the Euro showing that prior to Harvey being a hurricane? Or was it after it was undergoing RI that the Euro started showing those totals?
60.58" in the Golden Triangle (Nederland) from Harvey.

Hopefully, that run of the Euro is a fluke.
I remember reading some areas got up to 70 inches from Harvey.
https://www.nhc.noaa.gov/data/tcr/AL092017_Harvey.pdf

A weather station in Baytown had over 65 inches from Harvey. Not sure how credible it is.
https://www.wunderground.com/dashboard/ ... -3/monthly

Harvey rainfall totals before it re-developed in the Gulf of Mexico we 15 to 30 inches. After it developed, forecasted rainfall totals got higher.
Last edited by Ptarmigan on Sun Sep 12, 2021 2:29 pm, edited 1 time in total.
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tireman4
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000
FXUS64 KHGX 121840
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
140 PM CDT Sun Sep 12 2021

.AVIATION [18Z TAF Issuance]...

Deteriorating conditions are expected over the next 24 hours as
the initial rain bands associated with Tropical Storm Nicholas
move onshore overnight. Visibility reductions associated with
precipitation along with lowering cigs will result in MVFR to IFR
conditions persisting into tomorrow. Precipitation chances will be
highest across the metro and along the coast, but have carried at
a minimum vicinity wording at all terminals during this period.
Easterly winds will gradually veer to the southeast, remaining
around 10 knots inland and around 15 knots near the coast.
Conditions will likely worsen further in the coming days with the
continued approach of Tropical Storm Nicholas, which will bring
heavy precipitation and strong wind gusts.

Cady

&&

.PREV DISCUSSION /Issued 1108 AM CDT Sun Sep 12 2021/...

.SHORT TERM [Through Monday Night]...
Today marks the beginning of quite a dreary and rainy pattern.
Satellite-derived total PW reveals moisture moving in from the Gulf
early this morning with PW values already in 1.6"-1.8" range in the
western Gulf waters. Models are still in agreement on a large plume
of Gulf moisture moving in from the southeast this afternoon. PW
values by Sunday night will reach well over 2" for locations south
of and including Harris County with PW values near 2.5" closer to
the coast. Moisture will converge along a surface trough located
along the coast, so this is where most of the rainfall is expected
for today. The 00z run of the CAMs show a large swath of rain
moving ashore on Sunday afternoon with the main focus being right
along the coast that coincides with the location of the surface
trough. This is in line with the trends of the 00z run of the
global models as well.

The GFS, Canadian, and TTU-WRF are still hinting at a jet streak
developing over the CWA that would provide upper-level support for
the widespread rainfall, but the intensity of this is still a bit
uncertain with the Canadian being the strongest out of the three
solutions. Our saving grace initially is that we have been dry as of
late, so the soils will be able to handle the initial rounds of
rainfall (outside of any 3-4+" per hour rain rates). WPC currently
has areas south of a line from Columbus to Conroe to Livingston
outlined in a marginal risk for excessive rainfall with the counties
of Brazoria, Galveston, and Chambers in a slight risk for tomorrow.
The influx of tropical moisture will also bring below normal
temperatures with highs in the upper 80s/low 90s today and mid to
upper 80s on Monday. Overnight lows will be on the mild side in the
low to mid 70s.

Although this surge of moisture initially comes in on Sunday
afternoon, it is associated with Invest 94L in the Bay of Campeche.
NHC has given this disturbance a 90% chance of developing, which
lines up with the latest run of models that all agree that some
sort of low-level circulation will develop in the southwestern
Gulf. NHC is anticipating that a tropical depression is likely to
form as early as today. The track remains a bit uncertain as some
models push it inland over Eastern Mexico/South Texas and others
keep it offshore which would give it time to intensify. Either
way, we can expect numerous rounds of rainfall with the potential
for flooding where heavy rain bands (rain rates 3-4" per hour) set
up.

Through Monday night, anticipating rainfall totals south of
I-10 and along the coast of 3 to 5 inches with localized MUCH higher
amounts possible. HREF PMM shows some pockets double that closer
to the immediate coast and offshore. Last 2 runs of the TTU WRF
even higher. Whether that pans out or not, it shows the overall
potential seriousness of the situation. The slight risk of
excessive rainfall expands a bit further north for Monday to
include essentially the entire southern half of the CWA. A Flash
Flood Watch may be necessary by Monday for portions of Southeast
Texas as the heavy rainfall threat persists.

Batiste


.LONG TERM, TROPICS & MARINE [Tuesday Through Sunday]...
Potential for significant rains and flooding continues. The
forecast is highly dependent on the evolution of the area of
disturbed wx currently in the Bay of Campeche. Scatterometer
sample late last night showed no closed circulation yet...just an
elongated trof axis across the western Gulf. That said, guidance
does support some organization with time and a depression could
form later today or tonight. Tropical related watches/warnings may
be hoisted for portions of the Texas coast at some point today.

Track/intensity/timing/finer details all depend on location of
of any development, and the eventual level of organization.
General steering flow into early parts of the week will be to the
north...meaning toward the Tx coast.

For planning purposes, it wouldn`t be unreasonable to coastal
residents to prepare for tropical storm (and maybe even a strong
one) situated somewhere in the vicinity of the upper coast heading
into Tues.

Rainfall:
- Again, dependent on level of organization/location of the
system. A weaker, elongated trof axis to our west will allow a
fetch of deep Gulf moisture flowing into the region. A
strengthening system offshore would tend shrink the precip field
a bit closer to the center for a while until it makes its way
closer & landfall. Until there`s more clarity...the ongoing
7-day QPF numbers have remained about the same with the highest
numbers of 10-15+ inches near the coast and less so further
inland and northwest.

Flooding:
- Some southern locations will probably have seen some substantial
rainfall by early Tues and saturated grounds. Where this
happens, additional rain will runoff and quickly produce
additional flooding.
- Training heavy bands that produce rain rates of 2-3"+ per hour
will cause issues regardless the location...especially metro
areas.

Rivers:
- Need to keep a closer eye on the southern watersheds where some
of the heavier totals are forecast. San Bernard, Tres Palacios,
Lavaca, etc. Houston area bayous and creeks may, or may not,
become a concern depending on where the heaviest rain sets up -
but are not totally immune to potential issues.

Winds:
- Too early to say. For planning purposes, those along the coast
might want to begin preparing for tropical storm storm force
winds as we head closer toward Tuesday until things hopefully
become more clear cut and the forecast refined.
- For marine interests, winds should be in the 15-20kt range
through the day Monday. Sustained 20kt winds will probably
arrive in the nearshore waters Mon evening/night. Highly
uncertain if sustained 30kt+ winds will develop or when they`ll
arrive. Maybe some frequent gusts to around that late Mon night
& Tues. At this point, best to just watch the forecast.

Seas:
- 3 to 5 foot seas will build into early-midweek.
- Expect 6 foot seas to arrive in the nearshore waters Mon
morning.
- Peak seas maybe in the 10-15ft range sometime Tues depending on
what evolves.
- Seas fall below 6 feet nearshore Wed morning.

Coastal flooding/surge/rip currents:
- Tides are already around 1 foot above normal.
- Total observed levels will probably approach the 3.0-3.5 range
at high tide tonight - below coastal flood criteria.
- Concerns grow Monday night and Tues as levels further rise.
Coastal flooding is a decent possibility at that time, though
overall severity is highly uncertain at this point.
- Surge height...way too early to know...especially considering
nothing has organized at this point.
- High risk of rip currents along area beaches today into midweek.


Forecast beyond Wednesday is highly uncertain and just loaded NBM
in the grids which advertises scattered activity into the
weekend. There are some deterministic solutions out there that
begin to dry things out somewhat during the second half of the
week but confidence is too low to weight any one solution over
another. 47

&&

.PRELIMINARY POINT TEMPS/POPS...

College Station (CLL) 72 86 72 83 72 / 50 60 30 60 40
Houston (IAH) 73 83 74 83 74 / 70 80 60 70 60
Galveston (GLS) 77 86 80 83 79 / 80 80 70 90 70

&&

.HGX WATCHES/WARNINGS/ADVISORIES...

TX...Tropical Storm Watch for the following zones: Bolivar
Peninsula...Brazoria Islands...Chambers...Coastal
Brazoria...Coastal Galveston...Coastal Harris...Coastal
Jackson...Coastal Matagorda...Galveston Island...Inland
Brazoria...Inland Galveston...Inland Jackson...Inland
Matagorda...Matagorda Islands...Southern Liberty.

Flash Flood Watch from 7 PM CDT this evening through Tuesday
evening for the following zones: Bolivar
Peninsula...Brazoria Islands...Chambers...Coastal
Brazoria...Coastal Galveston...Coastal Harris...Coastal
Jackson...Coastal Matagorda...Fort Bend...Galveston
Island...Inland Brazoria...Inland Galveston...Inland
Harris...Inland Jackson...Inland Matagorda...Matagorda
Islands...Northern Liberty...Southern Liberty...Wharton.

GM...Tropical Storm Watch for the following zones: Coastal waters
from Freeport to Matagorda Ship Channel TX out 20
NM...Coastal waters from High Island to Freeport TX out 20
NM...Galveston Bay...Matagorda Bay...Waters from Freeport
to Matagorda Ship Channel TX from 20 to 60 NM...Waters from
High Island to Freeport TX from 20 to 60 NM.


&&

$$
dp6
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Central Texas is very prone to flooding.
West of I-35. East of there the soils are quite different. Not that anywhere can handle 60" (almost certainly a run anomaly) or even 30". But better in the rolling hills between Austin and Columbus than in super flat Houston. Easy for a person to avoid flooding in areas with rolling hills, while much/most of Houston is luck of the draw.
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