September 2020:

General Weather Discussions and Analysis
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Ptarmigan
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Re: September 2020:

Post by Ptarmigan » Sun Sep 27, 2020 10:16 am

tropiKal wrote:
Sat Sep 26, 2020 6:18 pm
Very wonderful rain this past week! Summer (Jun - Sept) was decent, not including the early July and late August dry breaks.

Hoping for a very warm and dry fall and winter. La Nina in place will thankfully ensure that.
Some big cold blasts have occurred in La Nina winters like in 1895, 1899, 1911, 1918, 1924, 1951, 1962, 1985, 1989, 1996, 2011, and 2018.

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tireman4
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Re: September 2020:

Post by tireman4 » Sun Sep 27, 2020 1:07 pm

000
FXUS64 KHGX 271805
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
105 PM CDT Sun Sep 27 2020

.AVIATION [18Z TAF ISSUANCE]...

VFR conditions expected today into early tonight transitioning to
MVFR to possibly IFR overnight as a cold front approaches the
northern regions of the CWA. S winds at 10-15 KTS with higher
gusts on occasion today and tonight, turning N and increasing to
15-20 KTS with higher gusts Monday morning in the wake of the
front. So far, HiRes Precip guidance is not too keen on bringing
significant shower and thunderstorm activity, therefore, kept the
mention of VCSH for this TAF package from around 08Z-15Z for the
northern portions, 12-18Z for the central portions, and an hour or
two later for the coastal portions. It could be upgraded to VCTS
in the next TAF package however. Once the front moves through the
local area, expect strong and gusty N winds to continue with skies
gradually lifting and scattering out starting from the northern
portions southwards throughout the late morning and afternoon
hours. Winds will slowly subside Monday night. 24

&&

.PREV DISCUSSION... /ISSUED 413 AM CDT Sun Sep 27 2020/

SHORT TERM [Today through Tuesday Night]...

Some patchy fog possible across northern portions of the CWFA this
morning, but given the slightly increased onshore winds just above
the surface, it`ll likely be more low clouds. These southerly flow
could also produce some very isolated showers along the coast this
morning. Otherwise, all of this is expected to mix out by mid/late
morning with another warm afternoon on tap. Highs should be in the
upper 80s to lower 90s.

Rain chances will begin to creep up over our northern counties late
tonight as the cold front begins its push into SE TX. While some of
the latest guidance is indicating a slightly faster motion, not too
confident with this at this time. Will keep with the previous fore-
casts with this line moving into the area overnight and likely into
our marine waters late tomorrow/Mon afternoon. The bulk of the POPs
will be just ahead of/along the front itself. Still not expecting a
lot in terms of rainfall as this line will be moving steadily. Much
cooler/drier weather on tap in the wake of the front...with lows in
the 50s Mon night! 41

LONG TERM [Wednesday through Sunday]...

Dry nw flow aloft should maintain pleasant wx across the area.
Surface high pressure will move off to the east around Thursday, but
weak onshore flow won`t time to modify the airmass before another,
albeit weaker, frontal boundary backdoors into the area late Thur
night and Fri. 47

MARINE...
Going to hoist the caution flags for a brief time period early this
morning as obs indicate 15-20kt winds offshore. These should
diminish a touch heading into the afternoon, but will probably creep
back up again for a while this evening and tonight. Other than
speeding up the frontal passage into the mid morning into early
afternoon hours on Monday, the fcst remains mostly unchanged. Small
craft advisories will be required in the wake of the front and gusts
to around gale force still look to be in play later in the day and
Monday night. Winds/seas gradually subside later Tue into midweek as
high pressure builds into the area. Light onshore winds may briefly
resume Thurs, but am expecting a weaker reinforcing front to
backdoor into the waters late Thurs night into Fri causing winds.
to back around to the northeast. 47

AVIATION [12Z TAF Issuance]...

Per the slightly elevated onshore winds at/just above the surface...
will be expecting more lower CIGS vs VIS for the rest of the morning.
Otherwise, VFR for this afternoon. Will be introducing the cold front
(wind shift) into the TAFs with this package...starting at CLL around
08-10Z and IAH from 12-14Z (but subject to to some last minute tweaks
before issuance). Gusty north winds progged in the wake of this front
during the day, decreasing a bit by evening (except along the coast).
41

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 65 76 55 79 54 / 30 20 0 0 0
Houston (IAH) 74 82 60 80 56 / 10 50 0 0 0
Galveston (GLS) 77 85 66 80 66 / 10 40 0 0 0

&&

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

$$

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DoctorMu
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Re: September 2020:

Post by DoctorMu » Sun Sep 27, 2020 1:28 pm

Given the arrival of the cold front into the northern counties in the wee hours of the morning the air would be expected to be less unstable. Modest chance of rain (downgraded to only 30%) and amount of rainfall in the Brazos Valley. 50% chance of rain Monday am in Houston.

Clearing skies Monday afternoon and serious northerly advection bringing much drier (DP in 40s possible in northern counties) and cooler temps Monday and Tuesday nights. Mid 50s in CLL, Upper 50s in NW Harris Co, Conroe. NW aloft flow for the week. A little reinforcement of coolish air mid to late-week. Highs in the upper 70s and 80s through the week.

The front should plow deep into the Gulf and essentially end Tropical Season for us, although there are exceptions...and it is 2020.

First extended Chamber of Commerce weather since April. Enjoy!



Edited - did not see tireman's post when I began putting this post together - just hitting the NOAA highlights.

FXUS64 KHGX 271805
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
105 PM CDT Sun Sep 27 2020

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

... Much cooler/drier weather on tap in the wake of the front...with lows in
the 50s Mon night! 41


LONG TERM [Wednesday through Sunday]...

Dry nw flow aloft should maintain pleasant wx across the area.
Surface high pressure will move off to the east around Thursday, but
weak onshore flow won`t time to modify the airmass before another,
albeit weaker, frontal boundary backdoors into the area late Thur
night and Fri.
47



.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 65 76 55 79 54 / 30 20 0 0 0
Houston (IAH) 74 82 60 80 56 / 10 50 0 0 0
Galveston (GLS) 77 85 66 80 66 / 10 40 0 0 0

&&

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

$$

Image

Image

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Re: September 2020:

Post by tireman4 » Sun Sep 27, 2020 2:32 pm

000
FXUS64 KHGX 272005
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
305 PM CDT Sun Sep 27 2020

.SHORT TERM [Rest of Today through Monday Afternoon]...

Fair but breezy weather conditions will continue today through early
tonight. Partly cloudy skies and winds of 10-15 MPH are expected to
prevail this afternoon with high temperatures reaching the upper 80s
to low 90s. Rain chances will increase tonight into Monday morning
across SE Texas as a cold front moves through the local area.
Locally, we will see showers and possibly isolated thunderstorms
ahead and along the boundary beginning along the northern areas
closer to midnight CDT, spreading into the central areas overnight
and reaching the southern areas early Monday morning. In the wake of
the front, rain chances will dissipate and winds will turn northerly
and increase to around 15 KTS with gusts of around 25 KTS. By Monday
late morning into afternoon, drier air will filter into the region
allowing skies to lift and scatter out starting along the northern
region spreading southward into the rest of the CWA Monday
afternoon/evening. No significant threat is expected with this
frontal passage, but the drier and cooler air mass will decrease
overall temperatures on Monday. High temperatures look to only reach
the mid to upper 70s across areas north of I-10 and the low 80s
across areas south of I-10. Very nice for September in SE Texas! 24

&&

.LONG TERM [Monday Night through Sunday]...

The main weather feature in the long term period will be the cooler
overnight low temperatures and the lower daytime humidities. On Tuesday,
Wednesday and Thursday lows will be mostly in the 50s inland and in
the 60s at the coast with Wednesday probably being the coolest as surface
high pressure settles into the area. Tuesday`s highs looks to stay
in the upper 70s to around 80, and then a warmup begins with readings
probably reaching the mid to upper 80s on Thursday. The next cold front
(much weaker and much less breezy/windy than Monday`s front) will work
its way through the area Thursday night through Friday morning. High
pressure behind this front will be centered well to our north as it
moves eastward, and this will bring area winds back around to the
southeast and south for the weekend. Friday`s low temperatures should
be a little cooler than Thursday morning`s readings, and then the area
can expect a gradual rising trend (both temperatures and humidities)
over the weekend.

Do not think anyone would be upset if record low temperatures were reached
during this cooldown, but sorry to say that`s not gonna happen.

42

&&

.MARINE...

Onshore winds will prevail tonight ahead of a strong cold front that
will move into the coastal waters on Monday morning. In the wake of
the front, strong northerly winds, with gusts possibly close to gale
force, can be expected later in the day and on into Monday night as
cooler air temperatures move across the warmer water temperatures.
Winds and seas should begin subsiding late Tuesday into midweek as
high pressure settles into the area. A reinforcing but much weaker
cold front is forecast to move into the waters late Thursday night
or Friday morning. Onshore flow returns to the area over the weekend
as surface high pressure behind the second front quickly moves off
to the east.

&&

.PREV DISCUSSION... /ISSUED 105 PM CDT Sun Sep 27 2020/

AVIATION [18Z TAF ISSUANCE]...

VFR conditions expected today into early tonight transitioning to
MVFR to possibly IFR overnight as a cold front approaches the
northern regions of the CWA. S winds at 10-15 KTS with higher
gusts on occasion today and tonight, turning N and increasing to
15-20 KTS with higher gusts Monday morning in the wake of the
front. So far, HiRes Precip guidance is not too keen on bringing
significant shower and thunderstorm activity, therefore, kept the
mention of VCSH for this TAF package from around 08Z-15Z for the
northern portions, 12-18Z for the central portions, and an hour or
two later for the coastal portions. It could be upgraded to VCTS
in the next TAF package however. Once the front moves through the
local area, expect strong and gusty N winds to continue with skies
gradually lifting and scattering out starting from the northern
portions southwards throughout the late morning and afternoon
hours. Winds will slowly subside Monday night. 24

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 64 76 52 79 52 / 40 20 0 0 0
Houston (IAH) 72 79 59 80 57 / 20 40 0 0 0
Galveston (GLS) 77 82 66 80 66 / 10 40 0 0 0

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...Small Craft Advisory from 7 AM Monday to 7 AM CDT Tuesday for
the following zones: Galveston Bay...Matagorda Bay.

Small Craft Advisory from 7 AM Monday to 1 PM CDT Tuesday 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...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.

&&

$$

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Re: September 2020:

Post by tropiKal » Sun Sep 27, 2020 4:44 pm

Ptarmigan wrote:
Sun Sep 27, 2020 10:16 am
Some big cold blasts have occurred in La Nina winters like in 1895, 1899, 1911, 1918, 1924, 1951, 1962, 1985, 1989, 1996, 2011, and 2018.
Again, the cold and precip only happen in the instances of La Ninas with El Nino permeations (i.e. SOI crashes). And even then, many of those years had great stretches of warm weather. So you can bet that with a proper La Nina, Houston will be warm and toasty with wall-to-wall sunshine.

Fortunately, the jet stream influence over Houston has been weakening since the 1990s - hence the general warmer, drier trends observed through the fall-spring period (especially obvious using HOU airport). And as it continues to weaken, Houston will start having more and more of a pure tropical perfection in its weather patterns!

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Re: September 2020:

Post by TXWeatherMan » Sun Sep 27, 2020 5:33 pm

tropiKal wrote:
Sun Sep 27, 2020 4:44 pm
Ptarmigan wrote:
Sun Sep 27, 2020 10:16 am
Some big cold blasts have occurred in La Nina winters like in 1895, 1899, 1911, 1918, 1924, 1951, 1962, 1985, 1989, 1996, 2011, and 2018.
Again, the cold and precip only happen in the instances of La Ninas with El Nino permeations (i.e. SOI crashes). And even then, many of those years had great stretches of warm weather. So you can bet that with a proper La Nina, Houston will be warm and toasty with wall-to-wall sunshine.

Fortunately, the jet stream influence over Houston has been weakening since the 1990s - hence the general warmer, drier trends observed through the fall-spring period (especially obvious using HOU airport). And as it continues to weaken, Houston will start having more and more of a pure tropical perfection in its weather patterns!
I really hope we don’t have a warm winter. You have that 8 months out of the year so I’m sure you can handle 3-4 months of “cold” weather.

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Ptarmigan
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Re: September 2020:

Post by Ptarmigan » Sun Sep 27, 2020 6:56 pm

TXWeatherMan wrote:
Sun Sep 27, 2020 5:33 pm
tropiKal wrote:
Sun Sep 27, 2020 4:44 pm
Ptarmigan wrote:
Sun Sep 27, 2020 10:16 am
Some big cold blasts have occurred in La Nina winters like in 1895, 1899, 1911, 1918, 1924, 1951, 1962, 1985, 1989, 1996, 2011, and 2018.
Again, the cold and precip only happen in the instances of La Ninas with El Nino permeations (i.e. SOI crashes). And even then, many of those years had great stretches of warm weather. So you can bet that with a proper La Nina, Houston will be warm and toasty with wall-to-wall sunshine.

Fortunately, the jet stream influence over Houston has been weakening since the 1990s - hence the general warmer, drier trends observed through the fall-spring period (especially obvious using HOU airport). And as it continues to weaken, Houston will start having more and more of a pure tropical perfection in its weather patterns!
I really hope we don’t have a warm winter. You have that 8 months out of the year so I’m sure you can handle 3-4 months of “cold” weather.
Winter is suppose to be cold. 8-)

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Re: September 2020:

Post by Cromagnum » Sun Sep 27, 2020 7:33 pm

Anyone that complains about cold this year needs a mallet upside the head. Im hoping for a proper fall season for once and winter that doesnt leave until Astrological spring or later. Tired of getting early summers that never leave.

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Re: September 2020:

Post by DoctorMu » Sun Sep 27, 2020 8:07 pm

Cromagnum wrote:
Sun Sep 27, 2020 7:33 pm
Anyone that complains about cold this year needs a mallet upside the head. Im hoping for a proper fall season for once and winter that doesnt leave until Astrological spring or later. Tired of getting early summers that never leave.
We've had a lot of northerly flow aloft since Sept 9th up here in the NW territories (CLL). 94°F has been the hottest day since then and over half the days the dewpoint has been under 70°F.

We're due after the last 2-3 year with stubbornly high DPs into November, even December. A brief snpp, then warmer than average January and February. Fingers crossed.

Looks like northerly upper air flow for the next 7-10 days.

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Re: September 2020:

Post by tireman4 » Sun Sep 27, 2020 9:24 pm

000
FXUS64 KHGX 272359
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
659 PM CDT Sun Sep 27 2020

.AVIATION [00Z TAF Issuance]...

VFR conditions with light to moderate southerly flow will continue
through midnight tonight, but an approaching cold front will bring
a northerly wind shift, MVFR CIGs of around 1500-2000ft, and a
line of showers and thunderstorms to the area late tonight and
into the first part of tomorrow. Looks like this line will be
through CLL around 7-8z, through IAH around 11-12z, then through
GLS and off the coast by 14-16z. As the front passes, it will
bring a line of precipitation with it. Have just kept the VCSH
wording, but an isolated thunderstorm can not be ruled out. Gusty
northerly winds will continue through the day behind the front
with gusts up to 20 to 30mph with the strongest gusts near the
shore. Expect clearing skies through the day as well. Winds relax
a bit overnight tomorrow night, but may still be sustained around
10 to 15 mph.

Important information for our users, the NWS will be completing
some maintenance on our internal network between 1am and 4am CDT.
This will result in a data outage of many of our products and many
products will not be transmitted to external users. Because of
this, all of our TAF sites will include "AMD NOT SKED 2806/2809"
in the 6z package. Unfortunately, this will be when the cold front
will be moving through CLL and UTS, so please be advised that
amendments may not be issued if conditions become unrepresentative.

Fowler

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