October 2021

General Weather Discussions and Analysis
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tireman4
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October 2021

Post by tireman4 » Mon Sep 20, 2021 6:14 am

Finally Fall? Will it be warm like October 2004. We shall see

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Re: October 2021

Post by 869MB » Fri Oct 01, 2021 12:19 am

0826D202-C9B9-4726-ACF2-104AE621F942.jpeg
Mesoscale Precipitation Discussion 1035
NWS Weather Prediction Center College Park MD
130 AM EDT Fri Oct 01 2021

Areas affected...central and south Texas

Concerning...Heavy rainfall...Flash flooding possible

Valid 010529Z - 011129Z

Summary...Slowly propagating storms associated with a loosely
organized MCS will continue to pose a flash flood threat through
the early morning hours.

Discussion...Deep convection in portions of south Texas continues
to be aligned along the leading edge of a very slowly forward
propagating MCS that extends from near Junction to near Del Rio.
The storms themselves were exhibiting fairly progressive storm
motions (260/30kt), but were fairly efficient rainfall producers
given environmental PW values of 1.6-1.8 inch. Despite the
forward motion of the complex, a couple of issues suggest at least
an isolated flash flood threat over the next 3-6 hours or so: 1)
a more west-east orientation of convection along the southwestern
flank of the MCS (near/just east of Del Rio) that has allowed for
some training to occur and 2) antecedent rainfall that has lowered
FFG values in parts of the region to the 1-2 inch/hr range
especially from the San Antonio area northwestward. MRMS estimates
of 1-2 inch/hr rainfall rates beneath the stronger convection in
the MCS suggests the presence of at least an isolated flash flood
risk.

Over time, models and observations both suggest that the ongoing
MCS will continue to propagate east-southeastward while
maintaining a favorable orientation for localized flash flooding
especially near training cells. If the storms hold together, they
should reach hydrologically sensitive areas of the Austin/San
Antonio corridor around 07Z. Both the HRRR and HREF suggest that
additional convection may develop ahead of the complex before
sunrise, which should also be slow-moving and efficient in terms
of rain rates given the high PW environment. FFG values are also
very low near coastal areas of Texas, and flash flooding will also
be possible in those areas.

Cook

ATTN...WFO...CRP...EWX...FWD...HGX...SJT...

ATTN...RFC...WGRFC...NWC...

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Re: October 2021

Post by tireman4 » Fri Oct 01, 2021 7:47 am

00
FXUS64 KHGX 011132
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
632 AM CDT Fri Oct 1 2021

.AVIATION...

For the 01/12Z TAFs, periods of SHRA/TSRA can be expected today with
MVFR and possible IFR ceilings in/around the stronger activity. Will
indicate a break in the activity by this evening, but more energy/
disturbances moving across the area could generate more storms during
the Friday night through Saturday time period. With lots of models
showing different timing and intensity forecasts for the rains, not a
whole lot of confidence with the 01/12Z TAFs. 42

&&

.PREV DISCUSSION... /ISSUED 418 AM CDT Fri Oct 1 2021/

DISCUSSION...

The prolonged stretch of unsettled weather we`ve seen this week
will continue, with more rounds of showers and storms expected
today and through the weekend. Thanks to the preceding days of
rain and potentially slow motion of showers and storms today, all
of Southeast Texas is in a slight risk area for excessive rain in
WPC`s outlook.

After this long stretch, look for a pattern change to come
following the passage of a cold front through the area Sunday
into Monday. Like most fronts in the early transition into fall,
the temperature change is not a big one - perhaps not noticeable
at all during the day, but we`ll see fair weather prevail with
some cooler nights and drier air.

SHORT TERM [Through Saturday Night]...

Showers and thunderstorms have begun to develop across parts of Southeast
Texas early this morning with enough instability and moisture in place
(infrared satellite imagery shows some cloud top cooling from east of
Houston to the coast). Not getting a whole lot of help from the models
early this morning with different solutions offering different timing
and location forecasts. Any leftover boundaries generated by the currently
developing activity in combination with more showers and thunderstorms
slowly edging in our direction from the southwest (where cloud top cooling
and storm intensity is greatest) and west could interact and produce
more storm development during the day today, and any additional mid/upper
level disturbances ejecting across the state tonight and Saturday could
produce more rounds of showers and thunderstorms. Until the cold front
moves through the area late in the weekend or early Monday morning (see
Long Term section below), locally heavy rainfall (at least 1 to 2 inch
per hour rainfall rates and possibly higher) cannot be ruled out with
some of the slower moving storms or where any training sets up. We will
be closely monitoring how this all unfolds, and similar to Thursday
we`ll hopefully only need to issue some Flood Advisories.

With the anticipated rains and associated cloud cover, will be keeping
the temperature forecast mostly untouched with lows mainly in the 70s
and highs in the 80s.

LONG TERM [Sunday Through Friday]...

Come Sunday morning, change is on the horizon - almost literally.
While the surface wind pattern looks fairly funky thanks to what
is probably going to be a pre-frontal trough, the front appears to
sit just northwest of our forecast area, poised to make its way
through the area.

But, wait - this isn`t quite a straightforward frontal passage
we`re looking at here. Things are a bit complicated by the fact
that there should be an upper ridge centered right over the Rio
Grande Valley and Deep South Texas, while the trough supporting
the advancing front is back up over Wisconsin. And, while there`s
a modest change in 850 temps in the post-frontal airmass, it isn`t
like we`re expecting an arctic blast here. All this is to say,
this front moving through is probably going to be slow and fuzzy.

How slow will it go? Probably pretty slow. The forecast takes the
front right on Houston`s doorstep Sunday afternoon. And...from
there...the front may do a bit of hokey pokey and actually drift
backwards overnight. Suffice it to say, Sunday looks fairly warm,
and may actually be the warmer day of the weekend with pre-frontal
heating, especially for those just ahead of the front during peak
heating. Here, generally along the coastal plain and into the
Houston metro, I have highs in the upper 80s. Similarly, PoPs are
maximized just ahead of the front`s expected location this
afternoon.

But, the front could be even slower. Looking at the NBM
distribution, the peak probability of having a high over 90 on
Sunday is in a band stretching across Caldwell, College Station,
and Huntsville. This still isn`t super high - just around 10
percent. But it does signal that there is a chance that the front
may not be quite as fast as is in my deterministic forecast. If
this occurs, you can likely slide the highest temps and PoPs back
to the northwest some. It`s not likely to significantly change the
character of Sunday`s weather over the area, but would make a
difference for a given point.

How things proceed from there looks like it might be a little on
the funky side. With a front bogging down, even retreating, we`d
probably expect it to wash out and leave its remnants draped
across the area as the upper trough ejects towards the Canadian
Maritimes. But there`s pretty strong consensus that a shortwave
trough will shoot through the longwave pattern, and drag a solid
ball of vorticity down to the Deep South while the upper ridge
slides back towards the US Southwest and amplify up the western
edge of the Great Plains. This should send the cold front back on
its way to the south, clearing the coast early Monday. Some
showers may be lingering around the coast on Monday as the front
moves out, but by Monday night, things will be drying out as the
drier post-frontal air surges in.

As mentioned before, the air behind the front is not a whole lot
colder, so don`t look for temperatures to plunge Monday night.
But, with modestly cooler and drier air coming in, most of the
area should see lows in the upper 50s and lower 60s. Only the
Houston heat island and the immediate coast should expect lows to
stay up in the upper 60s to around 70 degrees.

That should set the stage for the weather for most of the rest of
the week. Like so many frontal passages going into and coming out
of the summer, most of any cooling seen will be at night, while
mostly sunny sky and drier, more efficiently heated air will make
any daytime cooling small and quickly erased in the warming trend
as high pressure takes command of the area in the following days.

Fair weather should be expected to carry on as high pressure
drifts across the region while the upper ridge builds back
stronger over Texas. Look for the high to move enough to the east
for onshore flow to return mid-week, with a modest land/sea breeze
pattern resuming. As the upper ridge builds over the area, the
trend should be for slow warming through the week, but for now
expectations that we won`t drift too far above seasonal averages.
It`s a decent ridge, but the NAEFS mean for the ridge stays below
the 90th percentile through the work week, which should prevent
things from getting really torchy.

MARINE...

Light to moderate onshore winds and elevated seas will persist until
late Sunday or early Monday when a weak cold front moves across the
area. Periods of showers and thunderstorms can be expected until
the front moves through. Light to moderate north to northeast winds
will develop behind the front. Rain chances will come to an end late
Monday afternoon or Monday evening.

CLIMATE...

The City of Houston recorded 8.73 inches of rain in September which
is 4.02 inches above normal. Dating back to 1888, this total ranks
as their 12th wettest September on record. The wettest September on
record at this location is 14.95 inches set in 2019.

Here are some record rainfall totals for the next couple of days.

College Station area: 1.93 inches today (10/1) set in 1927 and
2.16 inches tomorrow (10/2) set in 1902.

City of Houston: 4.62 inches today (10/1) set in 1913 and 2.25 inches
tomorrow (10/2) set in 1995.

Hobby Airport: 0.89 inches today (10/1) set in 1933 and 2.24 inches
tomorrow (10/2) set in 2009.

City of Galveston: 4.73 inches today (10/1) set in 1933 and 4.90 inches
tomorrow (10/2) set in 1871.

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 84 71 84 70 87 / 60 30 80 30 30
Houston (IAH) 83 73 84 71 87 / 70 20 70 30 60
Galveston (GLS) 84 77 84 76 85 / 70 50 60 40 60

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&

$$

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tireman4
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Re: October 2021

Post by tireman4 » Fri Oct 01, 2021 8:36 am

Flooding Concerns..
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Re: October 2021

Post by Cpv17 » Fri Oct 01, 2021 9:14 am

We got a flood here in Rosenberg. Had a red cell sitting on top of us for 45 min.

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Re: October 2021

Post by don » Fri Oct 01, 2021 9:38 am

Heavy rain moving into the metro and surrounding areas at the moment. The system looks to be overperforming a little compared to what models were showing.

Mesoscale Precipitation Discussion 1036
NWS Weather Prediction Center College Park MD
714 AM EDT Fri Oct 01 2021

Areas affected...Southeast Texas

Concerning...Heavy rainfall...Flash flooding possible

Valid 011114Z - 011714Z

Summary...Relatively slow moving convection in an axis of much
above average PW values will continue to support heavy rains and a
flash flood threat in the vicinity of a stationary front across
southeast Texas through this morning.

Discussion...A very favorable pattern for heavy rains continue
across southeast Texas in the vicinity of a frontal boundary that
is expected to move little into this afternoon. The well defined
upstream closed low over New Mexico will continue to enhance large
scale lift in the axis of much above average PW values (1.5 to 2+
standard deviations above the mean) in the vicinity of this
boundary. This will support continued potential for organized
areas of convection across southeast Texas this morning. Latest
radar trends show convection enhancing farther to the southeast
from activity earlier this morning, into the region of greater
instability along and to the southeast of the stationary frontal
boundary, mu-cape values 1000-3000 j/kg. This is to the southeast
of where ffg values are the lowest from in the vicinity of San
Antonio westward to around 100W.

The hi res ARW, FV3lam and NAM nest are not doing well with their
simulated radar depictions versus what is occurring early this
morning. All of these models are exhibiting a typical hi res
guidance bias of being too slow to develop the convection,
especially where it is enhancing along and to the southeast of the
stationary front. The latest runs of the hrrr seem to be handling
the activity the best and all suggest an axis of heavy rains along
and especially to the southeast of the stationary front through
the remainder of this morning. Hourly rainfall rates of 1-2"+
likely with this convection over the next several hours, with
flash flooding possible. This may be especially so centered
around Corpus Christi where ffg values are the lowest and
convection is enhancing across this area currently.

Oravec
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mcd1036.gif
wpc_excessive_rvainfall_day1.us_sc.png

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Re: October 2021

Post by djmike » Fri Oct 01, 2021 10:35 am

Man heavy rain in Beaumont! Roads are starting to flood. Stay safe everyone!
Mike
Beaumont, TX
(IH-10 & College Street)

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tireman4
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Re: October 2021

Post by tireman4 » Fri Oct 01, 2021 10:57 am

000
FXUS64 KHGX 011623
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1123 AM CDT Fri Oct 1 2021

.UPDATE...

Widespread showers and scattered thunderstorms will continue to
slowly move north over the region this morning. Radar estimated
rainfall totals from 1 to 5 inches along and north of Highway 59,
with isolated higher amounts of 7-8 inches. The threat of moderate
to heavy rain is still expected north of I-10 through midday,
which is where the best mid to upper level forcing and instability
currently reside. Rainfall rates of 1-2"/hr are common, higher
rainfall rates up to 3 inches per hour are possible with any
strong storms. While the severe weather risk is low, sfc vorticity
and decent instability could support some weak updrafts.
Therefore, isolated strong storms will be possible with small hail
and gusty winds as the main threats.

The big question will be for additional convective initiation
later this afternoon. Current thinking is that the bulk of this
activity will gradually subside by mid afternoon as a stable
airmass begins to filter in from the west and upper level support
weakens and/or shifts outside of our region. With that said, the
heaviest precipitation and thus, the greatest rainfall amounts are
expected through late morning/early afternoon. However, current
soundings continue to show a very deep saturated layer across most
of the region with deep moisture convergence at the surface.
Given that, light to moderate rain and isolated thunderstorms will
be possible late this afternoon. Precipitation chances have been
updated accordingly with likely PoP through early afternoon, and a
20-35 chance of precipitation through the evening.

&&

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Re: October 2021

Post by Iceresistance » Fri Oct 01, 2021 1:31 pm

.65 Inches to end September, & I'm expecting the final wave of storms later tonight & into Tomorrow . . .

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Re: October 2021

Post by Kingwood36 » Fri Oct 01, 2021 2:34 pm

Ok..I'm over the rain now..it can stop now

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