445
FXUS64 KHGX 011159
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
659 AM CDT Mon Sep 1 2025

...New AVIATION...

.KEY MESSAGES...
Issued at 1248 AM CDT Mon Sep 1 2025

- One more day with scattered to numerous storms, along with a
  threat of localized heavy rain sticks with us for the holiday. A
  marginal risk of excessive rain (threat level 1 of 4) is in
  place for most of the area today.

- More tranquil conditions are expected for mid-week as drier air
  filters into the region. Isolated showers and storms may still
  pester the coast on Tuesday, with storm development gradually
  be pushed out over the Gulf by Wednesday.

- Of course, with fewer storms and clouds and without meaningfully
  cooler air moving in, high temperatures can also be expected to
  increase, with some highs creeping towards the middle 90s for
  Wednesday and Thursday. The drier air, though, will at least
  allow for cooler temperatures at night, as lows gradually slide
  through the 70s and into the upper 60s inland.

&&

.DISCUSSION...
Issued at 1248 AM CDT Mon Sep 1 2025

Even when we`re pretty confident that a holiday won`t give us an
infamous flooding event, the atmosphere still wanted to give us a
reminder of what it can do when things line up the wrong way.
Given the moisture and instability present, we had some
expectation that we could see localized flooding concerns emerge,
and we did indeed see that. The biggest instance of this occurred
in Houston, where 3-7 inches of rain fell in portions roughly near
the South and East Loop prompting a flash flood warning, street
flooding, and some water rescues. Fortunately, we did not
significantly overperform expectations as less than 2 inches fell
for most, area streams and bayous stayed within banks, keeping the
most serious issues in more flood-prone spots.

Going into the Labor Day holiday itself, we should see another day
with scattered to numerous storms cropping up. Indeed, the truth
is it`s not *truly* coming to an end tonight, but all storms
overnight will be out over the Gulf. Look for potential showers
to creep back onshore as early as the pre-dawn hours, but the
window for the day`s storms to really flourish should hold off
until the mid-day and afternoon.

Now, the front we`ve been talking about so much is offshore over
the Gulf now. However, the frontal surface aloft at, say, 925 or
850 mb is...not so much. On the bright side, this may temper gusty
winds if storms are just a bit elevated, though winds have not
really been so much a problem this weekend to begin with. One
thing it won`t do is stop the rain from reaching the ground, and
precipitable water values remain high. Northeastish winds at the
surface help out some, but at this late hour we still have PWATs
around/above 2 inches, and that doesn`t look to change a ton. HREF
probabilities of PWATs above 2 inches remain near 100 percent from
roughly I-10 coastward until late Monday night, and for much of
our area north of I-10, HREF probs are still more likely than not
that they are at/above two inches, as dry air filters in only
slowly.

But, since we are getting some erosion of the 90th percentile and
up levels of precipitable water, I`d expect that the best
potential for strong storms and big downpours will focus closer to
the coast today. WPC still draws a marginal risk area for
excessive rain all the way up to College Station and Huntsville.
This does still seem appropriate with the slower drawdown of
moisture, but there is surely a gradient in the underlying
probability of excessive rain that is being hidden in that
categorical outlook. One nice thing is that the coastal areas have
generally been less hit by stronger storms so far this weekend, so
they will be better poised to absorb the blows of any heavier
downpours. If I were to highlight an area of locally higher
concern, it may be in that area of Houston south of the Loop. This
area is on the fringe of that "coastal" area with more potential
for heavy rains - so while the probability of a big rainer isn`t
the highest in the area, it`s high enough when balanced with the
3-7 inches of rain they just got, making them more susceptible to
flooding. If they are able to dodge a strong storm, then no harm.
I`ll be crossing my fingers for that, but crossed fingers ain`t a
plan - so let`s all do our best to stay weather aware in that area
today, and promised not to drive through water-covered roads of
unknown depth!

After Labor Day, things should start to get a little calmer. A
deep eastern US trough will keep us in northwest flow, which isn`t
always great, but with a mid-week reinforcing trough helping get
even more dry air into the area, we should reach a point where it
doesn`t matter so much. I`ve still got us down for some isolated
to scattered convection on Tuesday as moisture levels draw down,
but I finally have the confidence to go dry for everywhere but
well offshore for the middle chunk of the week. Of course, the
flip side of this is that the cooler temperatures we`ve gotten
from the clouds and rain will also go away, with at least
seasonably hot temperatures coming back for Wednesday and
Thursday, plus some hotspots making runs for the middle 90s. At
least the drier air should help make those temps feel a little
less oppressive than typical, and also allow for things to get a
little bit cooler than average at night.

Finally, we`re still looking at another front at the end of the
week, but wow...after having such optimism a few nights ago, I`ve
all but lost the entirety of those good feelings (as a long-time
pessimism-leaning realist, that`ll teach me). We are still looking
at some appearance of unseasonably strong trough in the Southern
Plains, but it`s now tied more to the barely-there reinforcing
front and entirely out of the picture by late week. The Euro
ensemble does still briefly bring some 10th percentile 850 temps
across the Red River, but only for Tuesday night. By late week,
both the EPS and NAEFS mean 850 temps are nowhere near those low
probabilities, and now even some 90th percentile temps are
emerging. So...yup...guess I did well to only hedge slightly
against the NBM at the end of the week. At this point, I am now
barely deviating from the deterministic NBM numbers, except to
erase the not-actually-real Piney Woods hotspot it has.

&&

.AVIATION...
(12Z TAF Issuance)
Issued at 651 AM CDT Mon Sep 1 2025

All sites at VFR currently. Expect VFR to prevail through the
period. Showers and thunderstorms are expected again today, with
the focus of activity mainly south of I-10 and towards the coast.
Could see a few showers pop up north of I-10. Have left it as VCSH
through the afternoon hours. May need to update if showers or
thunderstorms move into the vicinity of terminals. Otherwise,
winds will be light and variable with VFR conditions overnight.

&&

.MARINE...
Issued at 1248 AM CDT Mon Sep 1 2025

The remains of a stalled front will continue to bring scattered
showers and thunderstorms to the region today. Some of the
stronger storms will be capable of producing locally heavy
rainfall and gusty winds. Since expectations are that the better
potential for storms today will be closer to the coast, these
storms could impact the coastal waters as well, particularly the
bays and nearshore Gulf. Winds outside of storms will generally
be light and variable, while becoming erratic and gusty in and
around any storms. Rain chances decrease significantly by the
middle of the week, while winds and seas are expected to remain
rather light/low.

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)  89  72  92  70 /  30  10  10   0
Houston (IAH)  89  74  92  74 /  50  20  20  10
Galveston (GLS)  87  80  89  80 /  50  30  40  10

&&

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

$$

DISCUSSION...Luchs
AVIATION...Adams
MARINE...Luchs