-- Discussion containing changed information from previous version are highlighted. --
969
FXUS64 KHGX 211710
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1210 PM CDT Tue May 21 2024

...New AVIATION...

.SHORT TERM...
(Today through Wednesday Night)
Issued at 306 AM CDT Tue May 21 2024

Warm, humid and hazy conditions will prevail with broad mid-upper
ridging stretching from Mexico & south Texas across the western Gulf
into the Mississippi Valley. Look for daytime highs 88-92F with
overnight lows 74-79F. A somewhat tighter pressure gradient will
lead to 13-20mph during the day and 8-12mph at night.

Though cannot rule out a few isolated sprinkles with saturated low
levels below the cap, mainly in the morning/late night hours,
wouldn`t expect any meaningful or measurable precipitation with
capping holding tough today.

A series of upper impulses riding over the top of the ridge
Wednesday, bring some broken to overcast conditions locally. Further
to our north and west, a dryline and a front serve as a focus for
shra/tsra development. There`s a non-zero chance extreme n/w parts
of the CWA see a rouge, remnant cell try to sneak in Wed evening
before dissipating...but again, chances much above 20% look generous
at this time. 47

&&

.LONG TERM...
(Thursday through Monday)
Issued at 306 AM CDT Tue May 21 2024

Today is International Tea Day, but given the ongoing period of hot
temperatures (and that we`re in Texas) it might be best to celebrate
it/cool down with a nice cool glass of iced tea. The general pattern
throughout the forecast period continues to be ridging aloft due to
persistent high pressure over northern Mexico. Temperatures will go
on an upward swing over the weekend, and so will the humidity
leading to heat index values well into the 100s. We`ll dive more
into that shortly, but first let`s talk about the ever so slight
chance of rain for portions of the Brazos Valley/Piney Woods.

With the ridging aloft remaining in place, we`ll have a subsidence
inversion layer around 850-750mb. So, as various shortwaves push
through and generate thunderstorms over north Texas, there is a
slight chance that some may survive long enough to make it to
portions of the Brazos Valley/the Piney Woods on Thursday. The
chances are low...but not zero. Elsewhere though, rain chances do
remain essentially zero through the weekend, so we`ll spend the rest
of the discussion talking about heat. Synoptically, we`ll see a
fairly steady pattern of a shortwave passing through the Four
Corners region generating surface low pressure on the lee-side of
the Rockies placing us in its warm sector. This in turn leads to
elevated humidity due to the increased low-level moisture transport.
High temperatures will be in the low 90s on Thursday and Friday with
heat index values generally in the 98-103F range. Over the weekend
is when the heat gets cranked up even more.

Southwesterly flow becomes established at 850mb over the weekend
leading to 850mb temperatures around or greater than the 99th
percentile (NAEFS/GEFS). Some of this warmer air will mix down to
the surface leading to air temperatures reaching the mid 90s for
most locations along and north of I-10. A frontal boundary will be
located to our west over the weekend as well (in association with a
surface low in the Central Plains). This particular boundary will be
fairly close to us leading to climatologically high PW values
ranging from 1.5-1.9" in the afternoons (90th percentile: ~1.80").
When you combine the hotter temperatures with the high humidity, we
get heat index values well into the 100s. It`s too early to lock it
in, but the potential is defintely there for Heat Advisories over
the weekend...especially Sunday and Monday/Memorial Day. We`re still
looking at an upward trend in heat risk as we go from a "Moderate"
risk (level 3 out of 5) on Thursday to a "Major" risk (level 4 out
of 5) from Friday onward. There won`t be much relief during the
overnight hours as low temperatures will only bottom out in the
upper 70s.

Given that a holiday weekend is coming up and I`m sure many of you
have outdoor plans, please be sure to practice heat safety: drink
plenty of water, take frequent breaks from the sun, avoid strenuous
outdoor activities during the hottest part of the day, wear
loose/lightweight clothing, know the signs of heat stroke/heat
exhaustion, and ALWAYS ALWAYS ALWAYS look before you lock your
vehicle. Don`t forget about your pets as well! If the ground is too
hot for the palm of your hand, then it is too hot for their paws.

While Memorial Day (Monday) looks to be the hottest day of the year
so far, this is also the day when rain chances return for a good
chunk of the region. Remember that frontal boundary we talked about
earlier? Well there is fairly decent model agreement that an upper
level low will push far south enough for that boundary to push into
Southeast Texas. This is still seven days out, so there`s a lot of
time for this to change...but even if this does pan out we`re not
looking at anything more than a cooldown of a few degrees.

Batiste

&&

.AVIATION...
-- Changed Discussion --
(18Z TAF Issuance)
Issued at 1207 PM CDT Tue May 21 2024

Scattered MVFR cigs will continue to improve marginally over the
next few hours, with a period of largely VFR cigs expected through
sunset. Low-end MVFR to IFR cigs will develop after 00Z, with the
greatest chances for IFR cigs near the coast and across the
northern terminals. Sustained winds remain around 10-12 knots, and
a few wind gusts of 15-20 kts will be possible this afternoon.
Overnight, winds mainly diminish to under 10 knots with the wind
direction remaining out of the southeast. Some improvement to cigs
is expected by daybreak tomorrow, but MVFR conditions may linger
into the early afternoon yet again.

Cady
-- End Changed Discussion --

&&

.MARINE...
Issued at 306 AM CDT Tue May 21 2024

Generally moderate onshore winds will continue throughout the week.
At times, winds and seas may increase enough for small craft to
exercise caution midweek and over the weekend. The persistent
onshore flow may increase the risk of rip currents towards the end
of the week and into the weekend.

Batiste

&&

.HYDROLOGY...
Issued at 306 AM CDT Tue May 21 2024

Minor to major river flooding continues for parts of Southeast
Texas, particularly along portions of the Trinity and Brazos
rivers. The following river points are either currently in flood
stage or are forecast to reach flood stage (as of early Tuesday
morning):

MAJOR//
-------
- Trinity River (Liberty): Major

MODERATE//
----------
- Trinity River (Goodrich): Moderate
- Trinity River (Riverside): Moderate
- Trinity River (Moss Bluff): Moderate
- Brazos River (West Columbia): Moderate (forecast)

MINOR//
-------
- East Fork San Jacinto (New Caney): Minor
- Brazos River (Richmond): Minor
- Brazos River (Rosharon): Minor
- Brazos River (Sugar Land): Minor

Remember to heed any instructions from your local officials and to
never travel through ANY flooded areas or roadways. TURN AROUND,
DON`T DROWN. Please monitor updated forecasts via the NWS AHPS
website and/or the new NWS NWPS webpage (https://water.noaa.gov/) as
the river flood threat persists.

Batiste

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)  91  76  91  76 /   0  10  10  20
Houston (IAH)  90  77  89  77 /  10  10  10  10
Galveston (GLS)  84  79  84  79 /  10   0  10  10

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
TX...None.
GM...None.
-- End Changed Discussion --
&&

$$

SHORT TERM...47
LONG TERM....Batiste
AVIATION...Cady
MARINE...Batiste