September 2021: Hurricane Nicholas

General Weather Discussions and Analysis
Stratton20
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CPV17 its toon soon to say that
Cpv17
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Stratton20 wrote: Thu Sep 23, 2021 10:26 pm CPV17 its toon soon to say that
Maybe. Models trended in the wrong direction today. Maybe tomorrow they will trend back wet again, hopefully.
Stratton20
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CPV17 hope they do! I love stormy weather, nothing better than a good old lightning show with some heavy rain😄
Cpv17
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Not quite as cool out there this morning but I still managed to get down to 55.
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tireman4
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000
FXUS64 KHGX 241133
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
633 AM CDT Fri Sep 24 2021

.AVIATION [12Z TAF Issuance]...

With high pressure remaining in place over the area, another calm
and clear weather day is expected with VFR conditions expected to
persist throughout. Easterly winds near 10 knots will develop this
morning, veering to the southeast during the afternoon and
becoming light and variable overnight. Minimal cloud cover is
anticipated with no cig/vis concerns.

Cady

&&

.PREV DISCUSSION /Issued 346 AM CDT Fri Sep 24 2021/...

.SHORT TERM [Tonight through Saturday Night]...

The synoptic pattern continues to be dominated by the presence of
surface high pressure over the south-central CONUS with weak ridging
developing aloft. As the surface high jogs further eastward during
the day today, winds will continue to shift gradually to the
southeast. However, wind speeds should remain relatively calm given
the relatively weak pressure gradient present across the area. As a
result, we should only experience a modest increase in temperatures
today as any impacts from WAA should be relatively insignificant.
Afternoon highs will reach the mid 80s at most inland locations,
staying closer to 80 along the coast. Conditions should remain
generally pleasant with dew points hovering in the upper 50s
/ lower 60s, though summer-like humidity will begin its gradual
return to the area as the onshore wind pattern strengthens in the
coming days.

The gradual return to heat and humidity continues on Saturday as
east/southeasterly flow gradually begins to strengthen offshore.
Another slight increase in highs (mid-upper 80s) and lows (near 60
to mid 60s inland, near 70 along the coast) is expected, though
surface dew points around 60 should keep things feeling relatively
pleasant. By Saturday night, the further eastward shift of surface
high pressure and a tightening pressure gradient over
central/eastern TX will allow for a more pronounced onshore flow to
begin to develop.

Cady


.LONG TERM [Sunday through Friday]...

High pressure will be located over the central Appalachians low
pressure developing in the lee of the Rockies. Surface winds
will slowly veer from the E to SE. PWATs remain low, generally
under an inch, so conditions not looking favorable for rain. Fcst
soundings don`t show much in the way of saturation so skies
expected to be partly to mostly sunny. 860 mb temps support
support MaxT values in the upper 80`s. Clouds return Sunday night
as low level moisture begins to deepen. PWATs deepen on Monday
and reach 1.80 inches by Monday afternoon. Weak warm air advection
(WAA) will increase, with gentle lift and weak surface
convergence coupled with the deeper moisture should generate some
showers Monday afternoon into Monday night.

On Tuesday, a robust upper level low over CA will move east into
the desert southwest. As it approaches upper level ridging expands
over South Texas into the western Gulf. Global models are in good
agreement that showers and thunderstorms will increase in coverage
but considering the strength and position of the upper level ridge
and the lack of surface convergence, not sure why models are so
aggressive. Yet models are in good agreement with mass fields but
have leaned toward the lower side of guidance until a trigger for
precip is found. That said, a speed max will approach SE TX
Tuesday night into Wednesday and that should help initiate precip
Tues night and Weds. Fcst soundings don`t show much capping on
Wednesday but they do show some very dry air in the 850-700 mb
layer which is troubling. Global models continue to trend wet for
Thursday and forecast profiles look semi saturated and PW values
remain near 1.90 inches. That said, the jet dynamics don`t look
favorable and SE TX will lie in the subsident region of the
jet. Will again temper my enthusiasm with regard to PoPs and lean
toward the lower side of guidance. Conditions will begin to dry on
Friday as PW values decrease to around 1.45 inches and capping
begins to increase in the 850-700 mb layer. High temperatures next
week show a slow warming trend but MaxT values will be strongly
dependent on cloud cover/precip. 850 mb temperatures support
surface values in the upper 80`s on Sunday warming into the lower
90`s by mid/late week. MinT values will warm up again surface dew
points climb back into the 70`s. 43


.MARINE...

High pressure over the eastern US and lower pressures over the
southern Gulf will allow for east winds to persist today and again
on Saturday. The pressure gradient will remain semi-lax and a
light to moderate onshore flow is expected. Pressures will begin
to drop in the lee of the Rockies on Sunday and surface winds will
veer to the southeast. The pressure gradient tightens a little
and wind speeds will gradually increase. Moisture levels will
increase and there will be a chance for precip Monday through
Wednesday. 43

&&

.PRELIMINARY POINT TEMPS/POPS...

College Station (CLL) 87 60 89 60 90 / 0 0 0 0 0
Houston (IAH) 84 61 85 62 87 / 0 0 0 0 0
Galveston (GLS) 82 73 82 74 85 / 0 0 0 0 10

&&

.HGX WATCHES/WARNINGS/ADVISORIES...

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

&&

$$
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DoctorMu
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^In summary, MEH on rain chances next week.
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tireman4
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00
FXUS64 KHGX 241735
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1235 PM CDT Fri Sep 24 2021

.AVIATION [18Z TAF Issuance]...

VFR throughout, albeit not *completely* SKC everywhere as some
FEW/SCT VFR-level clouds sneak in here and there. E/SE winds to
around 10kts this afternoon become near calm overnight, increasing
again towards mid-day tomorrow.

&&
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snowman65
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So......when is the next front????
Stratton20
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snowman65 your gonna have to wait a while for the next legit fall front, models arent really showing another good shot of cooler air in the next 7 days
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snowman65
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Stratton20 wrote: Sat Sep 25, 2021 11:47 am snowman65 your gonna have to wait a while for the next legit fall front, models arent really showing another good shot of cooler air in the next 7 days
wrong answer!🤣🤣
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DoctorMu
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A warm, unsettled week followed by warm/mild weather with reduced rain chances going into October. Time to put down the first batch of anti-fungal treatment on the lawn.

Nothing really of note. We haven't had much rain since August up here. Will gladly take an inch or precip. this week. Maybe two.
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DoctorMu
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Area Forecast Discussion
National Weather Service Houston/Galveston TX
635 AM CDT Mon Sep 27 2021

.AVIATION [12Z TAF Issuance]...

VFR conditions will mostly prevail during the day, though an
increase in moisture will result in gradually increasing cloud
cover as well as isolated showers around the metro and coastal
terminals during the afternoon. Activity should begin within the
next few hours offshore, expanding inland by 18Z. Showers will
taper off with the loss of daytime heating just after 00Z. As
winds shift to the south/southeast, further increases in moisture
at low levels will result in the development of MVFR cigs
overnight. Model soundings currently indicate a deck of around
2000-2500 ft developing after midnight, which should persist into
tomorrow morning as shower activity picks up again.

Cady

&&

.PREV DISCUSSION /Issued 330 AM CDT Mon Sep 27 2021/...

.SHORT TERM [Today through Tuesday Night]...

Recent surface observations and satellite-derived precipitable water
values indicate the surge of Gulf moisture pushing inland a bit
further east than originally anticipated, near Sabine Pass. While
the development of persistent and stronger onshore winds as
pressures deepen to our west will still bring about a return to
summer-like humidity today, the progression of the moisture plume
has shifted the greatest chances of precipitation to the east.
That
being said, isolated showers are still expected to develop along the
coast this morning and expand inland as the day progresses. However,
have focused this morning`s PoP forecast roughly in the Galveston
Bay area and locations eastward. The slight drop in precipitation
coverage will lend favorable to slightly higher high temperatures
this afternoon, with most locations in the metro nearing 90. Coastal
locations will remain varied based on rainfall development, but
should generally remain in the mid 80s. With the expected increase
in cloud cover concurrent with the arrival of deeper moisture,
overnight lows will struggle to dip below 70 region wide with urban
and coastal locations expected to remain in the mid/upper 70s.

Precipitation coverage will expand on Tuesday as a jet streak to the
south of an advancing upper trough axis over the Four Corners region
becomes positioned to our west, placing much of the area within its
left front quadrant. The arrival of additional moisture and the
favorable upper-level divergence that this pattern shift will
provide is likely to yield more widespread showers and thunderstorms
during the afternoon hours, and as a result have maintained PoP
values in the 40-50% range.
Precipitation coverage will increase
further during the evening as the jet streak advances further
eastward while an upper shortwave moves into central TX. Expect
daytime highs and overnight lows similar to Monday, though there
will be a bit more uncertainty in these numbers depending on
rainfall coverage and timing.

Cady


.LONG TERM [Wednesday through Monday]...

A strong speed max coupled with a weak short wave, a splitting
jet structure and PWATs between 2.00 and 2.15 inches will lead to
high rain chances on Wednesday.
Fcst soundings around the area
show a saturated to super-saturated profile which suggests some
potential for locally heavy rain in the stronger storms. PWATs
remain high on Thursday with values near 1.90 inches but most of
the moisture is confined to below 700 mb with considerably drier
air aloft. Upper level ridging also tries to expand into South
Texas with most of the short wave activity being shunted up and
over the ridge. Not real confident with the high PoPs for
Thursday
but the blends seem to like it as do most of the global
models. Upper level winds remain broadly divergent which should
aid in lift. Have gone with likely PoPs but again confidence not
real high at this time.
Another upper level low over the desert
SW will push east on Friday and a series of short waves will
rotate around the upper level feature and move into and across SE
TX. PW values increase to above 2.00 inches again and upper level
winds will remain broadly divergent. Fcst soundings did not show
much in the way of capping but some dry air was noted below 700
mb. Will again go with likely PoPs.

An upper level ridge over the western Gulf will expand to the west
and SE TX will begin to dry out from the east. PW values remain
around 1.90 inches but there is more low level drying noted below
700 mb. Will continue with chance PoPS for now but activity will
be fighting some subsidence with the building ridge as heights
increase to 591 dm. Models diverge significantly Sunday and
Monday as the ECMWF keeps things wet with a short wave over the
Southern Plains dropping a trough axis into SE TX both days while
the GFS expands the ridge and dries us out with PWATs falling to
1.50 inches. Split the difference and will maintain low end chance
PoPS for both days.
43


.MARINE...

A weak coastal trough will produce east winds today. The trough
will become diffuse as low pressure develops in the lee of the
Rockies. The flow will remain S-SE through much of the week ahead
with high pressure over the eastern gulf and low pressure over the
western high plains. The flow will become more easterly Friday
night and Saturday as weak low pressure develops over the southern
Gulf. 43

&&

.PRELIMINARY POINT TEMPS/POPS...

College Station (CLL) 91 72 92 72 89 / 0 20 20 50 70
Houston (IAH) 89 74 88 74 86 / 10 40 40 60 80
Galveston (GLS) 87 77 85 77 86 / 30 50 60 70 80
Cpv17
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The 12z Euro has widespread 3-6” totals for southeast TX. Lock it in!
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jasons2k
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Gutters cleaned again and ready. Felt a little muggy today but nothing unbearable.
Cpv17
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This could end up being a sneaky weather event this week. Wouldn’t be completely surprised to see some minor flooding issues in a few locations.
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tireman4
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000
FXUS64 KHGX 281153
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
653 AM CDT Tue Sep 28 2021

.AVIATION [12Z TAF Issuance]...

Challenging forecast on multiple fronts today. Period opens with
sporadic IFR CIG/VSBY at most sites, plus showers with isolated
lightning in the vicinity of SGR, HOU, LBX, and GLS. Expected
scattered to numerous showers/storms to spread inland this
afternoon, coming to an end in the early evening. Only a brief
break anticipated, with an upper disturbance bringing a new round
of showers and storms to the area.

Activity through the day will have a strong influence on the next
round of convection, and it is difficult to get too into specifics
for timing and impacts to individual terminals. Have tried to
sketch out windows with best chance for impact, for future shifts
to refine.

&&

.PREV DISCUSSION /Issued 349 AM CDT Tue Sep 28 2021/...

.DISCUSSION...

Expect a pretty active stretch of weather ahead right on through
to the weekend as an upper low spins more or less in place over
the southwestern US. Look for multiple rounds of showers and
thunderstorms through the week - so while we`re certainly not
looking for continuous rain through the week, and indeed, any
given point may not see rain every single day, that point will at
least have a decent shot each day until a pattern change arrives.

For the most part, the environment appears unlikely to support
any organized severe weather or widespread excessive rain.
However, we`ll have enough instability and moisture in place that
- as we see so often in Southeast Texas - a storm dropping high
rates of rain over the wrong spot could create brief spots of
localized, minor flooding.


.SHORT TERM [Through Wednesday Night]...

Showers in these overnight/early morning hours are 30-plus miles
offshore...for now. Based on GOES TPW imagery, it appears the
radar only begins to light up once precipitable water reaches two
inches. This deeper moisture is slowly making its way to the
Southeast Texas Coast; additionally, some warmer temperatures
aloft should begin to cool, weakening any remaining capping and
nudging up instability.

In other words, even though convection is currently well offshore,
we should expect that to change over the next several hours, with
potential showers and storms at the coast closer to dawn, with
coverage spreading inland and a general uptick in intensity
through the afternoon. That said, deep layer shear is pretty low,
which will temper the high end of today`s activity some. With
ample instability emerging and high moisture levels, the strongest
storms will be capable of dropping a quick inch or two, with the
best potential for this probably around the Galveston Bay area. If
this falls over a vulnerable spot, we could see localized
urban/poor drainage spots with minor flooding...pretty much par
for the course in Southeast Texas.

We`ll likely see activity chill out in the evening after the sun
goes down, but the break will be a short one. The next thing to
pay attention to will be a vort max associated with a shortwave
trough making its way out of Central Texas and across Southeast
Texas late tonight through Wednesday. This will certainly fuel
some amount of convection. I`ve got very high confidence that it
will rain somewhere in the area and some point while the vort max
aloft rolls through. The problem is...so much of the detail in
this round will depend on mesoscale details determined by what
happens today - boundaries, how much the atmosphere gets worked
over, all that fun stuff that makes getting into specifics very
tough, even 24-48 hours out.

Even better, some of the CAM guidance suggests that we`ll get
some early convection to fire, shoot west and collide with storms
moving east with the shortwave, then diving south towards Corpus.
This gives us storms in the southwest near Matagorda Bay, but
surprisingly little rain elsewhere in the forecast area. This idea
was emergent enough in the 00Z CAM runs that the HREF probability
matched 3-hr mean QPF is pushed to this solution.

It is perhaps unsurprising that, given the uncertainty involved, I
have spread out the PoP pattern areally, perhaps artificially
boosting things far inland northwest and north of the Houston
metro. Still...I don`t know that I`m totally convinced by this
aggressive right turn in the heaviest storms such that most of the
area gets missed. If things play out just how some of this CAM
guidance rolls, with strong, westward-moving convection blocking
things off, this outcome is probable. But if this "blocking"
convection isn`t strong enough, or even fails to materialize at
all, the shortwave should easily support showers and storms over
more than just our southwest.

On top of that, with an upper low spinning over the four corners,
it`s only a matter of time until the next little vort max rolls
across Wednesday night. This doesn`t appear to be quite as
substantial as the shortwave trough mentioned in the previous
paragraph, but it should be enough to drag PoPs right on through
the night.


.LONG TERM [Thursday Through Tuesday]...

The wet stretch of weather shows no signs of stopping through the
remainder of the week and into the weekend. The synoptic pattern
over SE TX will continue to be dominated by a vigorous upper level
trough positioned roughly over the Four Corners region, with a
robust associated jet streak positioned to its south. As broad
surface high pressure remains in place over the Southeastern CONUS
and pressures deepen over Western/Central TX as a developing lee
cyclone pushes into the OK Panhandle region, the resultant onshore
wind pattern will keep moisture abundant. Global models indicate PW
values hovering around 2.0 in by Thursday, with little change to
these numbers anticipated through Sunday afternoon.

As the upper trough axis pushes slowly to the east/northeast and
several embedded disturbances push through the Southern Plains, the
combination of ample moisture, favorable upper-level divergence, and
SBCAPE values on the order of 1500-2000 J/kg, will result in
scattered to numerous showers and storms developing each day with
activity peaking during the afternoon hours. Have generally
maintained PoPs of 60-80% through Saturday. Total rainfall amounts
of 2-3" are currently expected across SE TX through the end of the
weekend, though locally higher totals are certainly possible with
any stronger developing storms.

A pattern shift arrives on Sunday as the upper trough axis pushes
further eastward while the progression of a weak surface low over
the Northern Plains drags a cold front into Central/Southern TX.
While the latest GFS solution remains more progressive in its
depiction of the frontal passage through SE TX on Sunday night,
precipitation chances will nonetheless diminish with the loss of
upper-level support and drop off in total PWs to around 1.5 in.
Heading into the early part of next week, have kept PoPs in the
slight chance range with scattered/isolated diurnal activity
remaining a possibility.


.MARINE...

Winds continue to hover around advisory criteria this morning,
though have opted not to include advisory flags in the current
forecast package as seas remain generally light. A wet pattern is
expected to continue through the remainder of the week and into the
early part of the weekend as moderate onshore flow allows for a
steady stream of Gulf moisture to move into the area. Meanwhile,
with the onshore wind pattern remaining persistent, seas should
increase to around 3 to 5 knots by Friday. Expect scattered to
numerous showers and storms to develop each day with wind speeds
remaining near 15 knots. Any stronger developing storms may produce
stronger wind gusts at times.

&&

.PRELIMINARY POINT TEMPS/POPS...

College Station (CLL) 93 73 87 71 87 / 40 60 60 40 60
Houston (IAH) 87 74 84 73 86 / 70 70 60 50 80
Galveston (GLS) 86 78 84 77 84 / 70 70 60 60 80

&&

.HGX WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

DISCUSSION...Luchs
SHORT TERM...Luchs
LONG TERM...Cady
AVIATION...Luchs
MARINE...Cady
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Texaspirate11
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Really nice downpour here by the bay even with the sun out....
Just because you're disabled, you don't have to be a victim
Be Weather Aware & Prepared!
Barbara Jordan Winner in Media
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TexasBreeze
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Cpv17 wrote: Tue Sep 28, 2021 7:58 am This could end up being a sneaky weather event this week. Wouldn’t be completely surprised to see some minor flooding issues in a few locations.
Already taking place to the east of here and it is still early!
javakah
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After the wonderful cool, dry air we had in the mornings last week, I wanted to cry this morning when I went out this morning and found I was in warm soup. Ugh.
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don
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Getting some pretty high rainfall rates right now,looks like its at least at 2 inches an hour.Storms are moving though which should keep street flooding in check today.
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