Funnel Cloud in Texas, May 10, 2023

Area Forecast Discussion
National Weather Service Houston/Galveston TX
342 PM CDT Wed May 10 2023

...New SHORT TERM, LONG TERM, MARINE...

.SHORT TERM...
(This evening through Thursday Night)
Issued at 322 PM CDT Wed May 10 2023

Shower/thunderstorm activity associated with a now-departing
surface low and associated midlevel shortwave trough has
diminished as the aforementioned features have shifted to the east
over the course of the day today. That being said, latest radar
imagery continues to indicate the presence of scattered wrap-
around showers (and an isolated thunderstorm or two) which could
continue into the evening hours. Nonetheless, the evening commute
should be quite a bit less messy than this morning as rain rates
have diminished considerably across SE TX compared to the
overnight and morning storms today. Some ponding may still remain
on area roadways, especially in typically flood-prone areas.

With a saturated ground and low dewpoint differentials across the
area overnight, we could see the development of localized patchy
fog at times. However, this potential will be limited by elevated
winds thanks to a fairly tight surface pressure gradient. Any
patchy fog should diminish upon the advent of daytime heating
tomorrow morning, Overnight widespread cloud cover will work
against radiative cooling, which combined with persistent WAA will
keep temperatures in the upper 60s to lower 70s.

Tomorrow, scattered showers return to the forecast, mainly to the
north of the I-10 corridor as today's midlevel trough continues to
gradually shift to the east. While forcing is not particularly
strong, deep moisture (PW of ~1.7in) will prove favorable for the
development of some showers and storms during the afternoon hours.
For now, have maintained PoP values generally in the range of 30%,
and rain rates are not expected to be particularly intense.
Rainfall amounts are generally not expected to exceed a quarter of
an inch throughout Thursday. Some breaks in the cloud cover along
with persistent WAA will allow for high temperatures to reach the
upper 80s for most locations, while overnight lows will struggle
to dip below 70.

Cady

&&

.LONG TERM...
(Friday through next Tuesday)
Issued at 322 PM CDT Wed May 10 2023

Friday morning starts, and we've still got an upper trough in the
northern stream off to our northwest and subtropical ridging from
the Atlantic, keeping us smack in a Gulf moisture channel. By
Saturday, the Euro ensemble mean has precipitable water above the
90th percentile across the area, and while not quite that high in
the NAEFS, its mean PWAT is around or above 1.5 inches. Numbers are
even higher to our west, though, and that's where we get into the
key differences for our expectations this weekend.

The upper trough chilling way off to our northwest right now is
moving slowly, but should be over the Northern/Central Plains for
the weekend. Meanwhile, the next upper trough is dropping in for a
weekend trip to Vegas, baby! This creates a bit of a shortwave ridge
in the upper pattern, mucking up the flow of shortwave troughs
aloft. So, what had been traveling right over our coastal area the
past day or two is now getting hung up over West Texas.

So, while we'll have plenty of moisture and surely some modest
forcing, the main focus for heavier rain this weekend is looking
more like it will be west of our forecast area. Rain chances are
still looking pretty decent for most of the area, and locally heavy
rain may still be a concern in our west from Matagorda Bay up
towards the Brazos Valley...but in general I'd expect activity
closer to "typical spring rain". Granted, that can still be a pretty
slug of rain because Southeast Texas, but potentially less of a
concern than we've seen this week already.

Of course, this is a fairly awkward setup, and one I don't
necessarily have a ton of confidence in for even a 3-5 day forecast.
Something we'll have to watch for is if that lead northern stream
trough is able to eject a little more quickly, opening up the flow
for our local forcing to push farther east and move that heavy rain
focus more towards our area. Fortunately, I think it's mostly just
my own anxiety fueling this concern. A look at the multi-model
cluster analysis doesn't really show much obvious signal for a
notable drift from the ensemble mean, so there isn't really a solid
reason for doubting that as the best way to go here.

Heading into next week, things look awfully seasonable, particularly
after a modest front makes its way through the area Monday night or
Tuesday. Ensemble means don't stray too far from climatological
averages, and anything showing up in the Euro ensemble's Extreme
Forecast Index is far enough west in the state to not be any of our
concern. And since seasonable is what the NBM gives me, I'm
generally of a mind to more or less go along with it outside of
correcting for known biases (hey there, afternoon undermixing!).

One note of caution on this far part of the forecast, though. Even
though the end results are roughly seasonable, there is
some...uh...wacky stuff happening in the upper air pattern out over
the Western US. This on its own is not so weird. The pattern itself
showing hints of blocking kind of implies that we should anticipate
some odd flow, retrograde action, fun stuff like that.
But that kind of disturbed flow is, by its very nature, going to
mean less confident predictions. Part of a bonus of going with the
guidance consensus here is that if we need to make any changes in
the days to come, those changes won't be abrupt. I don't think it
will be a serious issue - the subtropical ridge looks like it should
be enough of a stabilizing influence over us that any changes aren't
likely to be drastic. But, something like...say...the timing of a
weak front dropping through probably need to be viewed with more of
a fuzzy, holistic lens here.

&&

.AVIATION...
(18Z TAF Issuance)
Issued at 1235 PM CDT Wed May 10 2023

Rain coverage continues to diminish this afternoon as the storm
system that brought this morning's storms departs the area. That
being said, MVFR to occasionally IFR cigs along with scattered
showers and storms will remain a possibility into the early
evening hours. Overnight, MVFR cigs remain in place with S to SE
winds just under 10 knots. While this should be enough to inhibit
fog development, some patchy fog cannot be ruled out. Tomorrow,
cigs begin to slowly lift but remain within MVFR thresholds for
the duration of the TAF period.

Cady

&&

.MARINE...
Issued at 322 PM CDT Wed May 10 2023

A long fetch of moderate to strong southeast winds will persist
through this weekend, allowing for somewhat elevated seas at times.
Caution flags or small craft advisories may be needed for portions
of this stretch. Periods of unsettled weather are expected with
showers and thunderstorms as a series of upper level disturbances
passes through the area. Highest rain and storm chances are expected
through late this evening, but daily chances can be expected through
early next week. A modest front may reach the waters early next
week, but confidence at this time is relatively low.

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)	  69  87  73  87 /  20  20  10  40
Houston (IAH)			  71  87  75  86 /  20  20  10  30
Galveston (GLS)			  74  85  77  83 /  10  10  10  20

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Flood Watch until 7 PM CDT this evening for TXZ178-179-199-200-
     210>214-226-227-235>238-300-313-335>338-436>439.

     High Rip Current Risk through Thursday morning for TXZ436>439.

GM...Small Craft Should Exercise Caution until 11 PM CDT this evening
     for GMZ330-335-350-355-370-375.

&&

SHORT TERM...Cady
LONG TERM....Luchs
AVIATION...Cady
MARINE...Luchs