Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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778
FXUS64 KHGX 221108
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
608 AM CDT Sat Jun 22 2024

...New AVIATION...

.SHORT TERM...
(Today through Sunday Night)
Issued at 210 AM CDT Sat Jun 22 2024

Ridging in the mid to upper levels of the atmosphere should bring
warmer conditions over the weekend and into the beginning of next
week. Even with abundant moisture still available, subsidence from
this ridge will limit rain chances. If any showers/storms do
develop, it`ll probably be on Sunday, with isolated development in
areas south of I-10 with support from the sea breeze. Minor coastal
flooding remains a concern today for coastal areas from High Island
to San Luis Beach. Water levels ares still expected to reach 3.5 ft
above MLLW later this morning with high tide. Coastal flood
advisories remain in effect for these coastal areas until 10 PM
tonight. Coastal communities should continue to exercise caution
while traversing these areas to allow waters to recede from any
impacted roadways.

Rising 850mb temperatures and decreasing cloud cover during the
afternoon suggest warmer conditions over the next few days
(especially with lacking rainfall). Highs will be in the upper 80s
to upper 90s over the weekend, with lows in the 70s to lower 80s
near the coast. Previous days have indicated afternoon mixing for
dewpoints has been rather poor, resulting in elevated heat indices.
By Sunday, heat indices are expected to reach 104-110 during the
afternoon hours, which may warrant a Heat Advisory during the day.
The heat risk for Sunday will be moderate (3/5) for most people
participating in low-impact, leisurely outdoor activities. However,
those participating in strenuous outdoor activities may feel major
(4/5) heat stress. Remember to drink plenty of fluids, wear
lightweight clothing and avoid strenuous outdoor activities during
the hottest part of the day.

03

&&

.LONG TERM...
(Monday through Friday)
Issued at 210 AM CDT Sat Jun 22 2024

One could very likely get away with hand-waving over the long term
portion of the forecast with "It`s summer". And, while tempting,
we`ll get into discussing things a little more in depth than just
that. But also, as long as you`re considering that heat safety
practices are now just typical summer behavior around here
(Narrator: they are) - it wouldn`t be totally wrong to leave it
there.

Alright, so...next week. The big story is really going to be
nuances in subtropical ridging - where it`s strongest, and just
how strong it looks to be. And of course, at range, the place we
really want to be looking for that is in the ensembles. Using mean
500 mb heights, both the NAEFS and Euro ensemble show a strong
ridge on tap for next week. NAEFS is a little bit weaker, showing
pretty persistent 90th percentile heights for much of the week.
The EPS is a bit stronger, and perhaps with the domiest part of
the heat dome centered a little farther east over Texas. As a
result, some mid-level heights over the 97.5th percentile start to
creep into the area. These well-above average heights finally fade
out late in the week as a shortwave trough dives in...mostly to
our east, but close enough to knock down those 500 mb heights
below the 90th percentile.

Taking it down a bit lower in the column, and we see a somewhat
similar, but more modest pattern in 850 mb temps. 90th percentile
850 temps emerge over our area in the both the NAEFS and EPS
Wednesday and Thursday, but otherwise below the 90th percentile.
Finally, at its most modest, there is virtually no signal for
extreme high temps in the area in the Euro ensemble`s Extreme
Forecast Index. So, ultimately, when the NBM gives me a string of
highs in the mid-90s, which is definitely above average albeit not
eye-poppingly so...I`m largely cool with taking what it gives me.
The primary exception is on the immediate coast - due to what I
suspect are land/water interface issues, Galveston and similar
spots are just too cool, so I nudged the "island" zones up a bit
to account for that.

Of course, around here, the raw temperatures are not the only
consideration to make here when it comes to heat threats.
Sometimes humidity can be just as, or even more important. So
where do things stand here? Well, it`s looking kinda rough,
especially deeper into the week. NBM lows are pretty unanimously
in the mid to upper 70s, except on the coast, where temps have
trouble getting below 80. This is a pretty solid indication that
we are dealing with a high moisture airmass dominating SE TX
through the week. During the daytime, peak heat index values drift
up and up and up through the week, from a point where we might
need to consider heat advisories, to where if the NBM were to
verify, we`ll eventually need widespread heat advisories, and
maybe even consider excessive heat warnings.

Now, I am a bit concerned here that this may be a bit on the
aggressive side. NBM is infamously too high with afternoon
dewpoints, and that implies that these heat index numbers might be
a bit inflated because of that. However, it doesn`t seem to
struggle as much with overnight dewpoints, and we can see the
upward trend in low temps, so...maybe there`s a little something
there? For now...stay tuned. Our daily dance of temp, humidity,
sun, and wind is going to go through a daily evolution, and we
should be able to flesh out expectations in the days to come.

Another confounding factor comes down to something I haven`t even
brought up yet, and that`s the potential to have things disrupted
by rain/storms. Each day this week, we can expect to see the
typical diurnal pattern for cloud and shower development, with any
activity focused more over the Gulf in the late night/early
morning hours, and gradually shifting towards coastal areas and a
bit inland with the seabreeze in the afternoon. In the first half
of the week, I`d expect the amplitude of this pattern to be more
muted, with even peak afternoon activity being isolated to widely
scattered at the most. Late in the week, when that shortwave
trough I mentioned briefly up top is rolling through, that may
create a modestly more conducive environment for afternoon
showers and storms, with more scattered coverage near the
seabreeze. Regardless of how it plays out precisely, the character
of this activity will be very spotty. Rainfall amounts may vary
wildly, with most seeing little to no rain, but those to win the
day`s rainfall lottery could see a brief little downpour before
that shower moves off and/or dissipates.

Luchs

&&

.AVIATION...
(12Z TAF Issuance)
Issued at 502 AM CDT Sat Jun 22 2024

Patchy fog should clear shortly after sunrise with VFR conditions
and E/SE winds prevailing during the day. Winds become light and
variable this evening. Patchy fog and MVFR decks may develop again
during the early morning hours of Sunday.

03

&&

.MARINE...
Issued at 210 AM CDT Sat Jun 22 2024

Small craft should continue to exercise caution tonight and
Saturday, in particular over the offshore waters as seas continue
to subside. Light to occasionally moderate onshore flow will
develop Sunday and continue through the next few days. Long
period swells associated with the next potential tropical
disturbance are possible later in the weekend into early next
week. There will be a daily risk of isolated showers and
thunderstorms every day through next week.

At the coast, some lingering minor coastal flooding may occur at
and near today`s high tide cycle. This is a particularly concern
around Galveston Bay, and most specifically on the Bolivar
Peninsula, where water levels at high tide are expected to again
reach around 3.5 feet above MLLW. Additionally, emergency managers
report that a good deal of erosion has taken place on area beaches,
increasing the vulnerability to coastal flooding. So, while the
Bolivar is of particular concern, the coastal flood advisory
around the entirety of Galveston Bay will remain in place today.
Also, there is still some elevated potential for dangerously
strong rip currents on all Gulf-facing beaches, so that will be
another consideration for those headed on a Saturday trip to the
water.

Luchs

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)  94  72  96  76 /   0   0   0   0
Houston (IAH)  94  75  95  77 /   0   0  20   0
Galveston (GLS)  88  81  89  82 /   0   0  20   0

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Coastal Flood Advisory until 10 PM CDT this evening for TXZ214-
     313-338-438-439.

     High Rip Current Risk through this evening for TXZ436>439.

GM...Small Craft Should Exercise Caution through this evening for
     GMZ370-375.

&&

$$

SHORT TERM...03
LONG TERM....Luchs
AVIATION...03
MARINE...Luchs