337
FXUS64 KHGX 081800
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
100 PM CDT Wed May 8 2024

...New AVIATION...

.SYNOPSIS...
Issued at 407 AM CDT Wed May 8 2024

We are now solidly into May, and the forecast is looking very
May-like. We are beginning to climb into our summer heat, and
multiple days will carry a very conditional thunderstorm threat.
The chance for any storms at all will be low...but any isolated
storm that does manage to get going may become strong to severe.
A few key points on the week to come:
- Today and tomorrow will feature highs in the upper 80s and low
  90s. Heat index values look to peak out around or just above 100
  degrees - not the hottest we`ll see, but the hottest we`ve seen
  in a while, and could be hazardous to unacclimated bodies that
  go too hard out in that heat.
- This heat will also provide a pool of fuel for any storm that
  manages to form in spite of a stout cap. The best chance for an
  isolated strong to severe storm will be mainly north of the
  Houston metro, with a bit better and wider chance Thursday than
  today. SPC`s severe weather outlooks are at a slight risk, level
  2 of 5, in the northernmost portion of our area, and higher even
  north of that.
- After a too-short break, we`ll be back on the lookout for
  locally heavy rainfall by Sunday. In their experimental Day 5
  outlook for excessive rain, WPC shows a slight risk, level 2 of
  4, centered roughly along I-10 and covering the bulk of our
  area. This far out, it`s important not to get too tied to the
  specific location of these risk areas, as they can shift from
  day to day, particularly looking several days out. The presence
  of this slight risk area should be a signal to everyone in
  Southeast Texas to keep an eye on how the forecast for Sunday
  and early next week evolves.

&&

.SHORT TERM...
(Today through Thursday Night)
Issued at 407 AM CDT Wed May 8 2024

College Station remains the only primary climate site to have
reached 90 degrees in 2024, picking up their hottest day of the
year so far. However, everyone else is gonna give it a good shot
today and tomorrow, with high temperatures right around 90 degrees
expected for two more days. Pair that with dewpoints in the 70s,
and we can look for heat index values to peak out near or above
100 degrees for all but the immediate Gulf Coast both days. For
those that spend time strenuously working and may be interested in
the Wet Bulb Globe Temperature, our forecast corresponds a
moderate to high risk of heat illness, and indicates a need to
begin factoring in the impact of heat to outdoor work, especially
for unacclimated folks (pretty much all of us right now).

Just to re-emphasize what I wrote above in the synopsis: even
though this is not even close to the hottest we`ll get this
summer, as far as heat stress is concerned, it`s much more
relevant that this stretch is the hottest it`s been in some time.
Heat illness numbers can spike at lower levels early in the warm
season, as people will get going a little too much for what their
body is acclimated to. So even though these numbers may not be
eye-popping to you, it`s a good time to practice spending more
time indoors, or at least out of the sun, and taking more frequent
rest and water breaks.

Beyond the impact of the heat itself, a lot of heat and humidity
also indicates plenty of fuel available for strong
thunderstorms...if any manage to get going. And that is an
extremely big "if" today and tomorrow. The main catalyst for
severe weather in the US will be far north of our area, and
unlikely to overcome the strong cap built out by solid southwest
flow just above the surface today. There does look to be a very
weak upper shortwave trough rolling through later today, and may
be just enough support for vertical motion that we get an isolated
storm going. If a storm can tap into that available instability,
it can easily become strong to severe. Today especially, that
threat should be confined to the very northernmost portions of our
area of responsibility (and really beyond that for more
significant threats). Large hail and damaging wind gusts would be
the primary hazards. A brief tornado isn`t impossible, but it is a
lower concern relative to hail and wind.

Tomorrow looks much the same as today when it comes to storms. A
very conditional threat where there`s plenty of instability to tap
into, but will require any storms to get going in the first place.
Like yesterday, we`ll again be looking for a weak shortwave trough
to stream through and provide a bit of help to any developing
storm updrafts, likely late Thursday afternoon into the evening.
The key difference from today is that the southwest flow at low
levels that should build out a strong cap are expected to break
down at some point tomorrow. This could make it easier for
isolated to widely scattered storms to break out. The severe
threat is again higher to the north of the Houston metro, but the
weaker capping flow allows for some severe threat to expand
across more of Southeast Texas. A slight risk area (level 2 of 5)
covers the northern bulk of the area, roughly north of I-10, and
an enhanced risk area (level 3 of 5) comes up right to the edge of
the boundary between our forecast area and that of our colleagues
in Fort Worth. That means that it probably behooves folks in
Burleson, northern Brazos, Madison, and Houston counties to keep a
wary eye up to the northwest, as a small change in expectations
could result in a greater severe threat for them. Large hail is
the primary hazard to watch out for tomorrow, with damaging wind
gusts coming in a close second. Like today, a tornado can`t be
totally ruled out, but is not as great a concern as the other
severe hazards.

&&

.LONG TERM...
(Friday through Tuesday)
Issued at 407 AM CDT Wed May 8 2024

A weak cold front will push off the coast during the early morning
hours of Friday, ushering in drier and slightly cooler weather into
the early weekend. Expect mostly clear skies during the day, with
afternoon highs in the upper 70s to upper 80s. Lows overnight will
be in the 60s with isolated locations in the upper 50s.

Surface high pressure slides east through the Southern Plains on
Saturday, allowing onshore flow to gradually return during the day.
Remnants of the frontal boundary starts to gradually lift north as a
warm front later in the day, suppling additional moisture and
bringing PWs of 1.5-1.8 inches. Lifting from the boundary will be
further supplemented by weak impulses aloft from a cutoff low over
the Desert Southwest. This should produce scattered showers and
storms, beginning over out west/southwestern Saturday evening and
spreading to the remainder of SE Texas into Sunday morning. Around
this point, the closed low/trough will be near the TX/OK Panhandle,
providing additional lift overhead. Combining this forcing with the
lifting warm sector should allow for more widespread
showers/thunderstorms to develop during the afternoon. Forecast
soundings also suggest high precipitation efficiency in this
environment, favoring the potential for locally heavy rainfall. WPC
has portions of SE Texas under a Slight (level 2/4) to Marginal
(level 1/4) Risk of excessive rainfall for Mother`s Day on Sunday.
We`ll get more specifics on how this next system will unfold over
the next few days.

Shower/storm activity decreases overnight into Monday as the
aforementioned upper trough slides eastward into the Mississippi
River Valley. Lingering moisture will keep scattered/isolated rain
chances throughout the day and into Tuesday as well.

&&

.AVIATION...
(18Z TAF Issuance)
Issued at 1226 PM CDT Wed May 8 2024

A mix of MVFR to VFR cigs currently across SE Texas sites and
S-SE winds are generally at 10-15 KTS with some higher gusts on
occasion. There is also lingering HZ over the area, which is
limiting vis to 4-6 SM at some locations. Cigs are slow to lift
today but are expected to lift a little more and scatter out this
afternoon and early evening. Some sites, however, could continue
to see MVFR cigs through the entire period. Expect the MVFR cigs
to return for most, if not all, of SE Texas however. Areas of
patchy fog could also reduce vis during the overnight to early
Thu morning period.

Another gradual improvement is expected late Thu morning into
early afternoon for both cig and vis conditions. Later in the
afternoon to evening hours, SH/TS could develop, in particular
over areas north of the I-10 corridor. Some of these storms could
be strong to severe and may produce large hail and strong gusty
winds. Another hazard to note is that lvl WS could occur over
sites north of IAH mid afternoon through late evening.

24

&&

.MARINE...
Issued at 407 AM CDT Wed May 8 2024

Light to moderate onshore flow is expected through Thursday ahead of
a frontal boundary. This persistent fetch will bring seas of 3-5
feet in the Gulf and elevated tide levels along the coast. High
flows from rivers, creeks and streams will lead to above normal
water levels in the bays and intercoastal water way today, which may
make navigation difficult at times. A weak cold front pushes
offshore during the early morning hours of Friday. Moderate north to
northeasterly winds develop in the fronts wake, warranting caution
flags into the weekend. Onshore flow returns Saturday evening, with
rain chances increasing into Sunday as our next weather system
pushes through the region.

&&

.HYDROLOGY...
Issued at 340 PM CDT Mon May 6 2024
Updated at 407 AM CDT Wed May 8 2024

There are low chances for thunderstorms today and Thursday, but
is not expected to result in any additional flooding concerns.
Rivers will remain swollen for days (possibly weeks), however. Do
NOT go around barricades and stay out of the floodwaters. Do NOT
return to homes until officials deem that it is safe.

Minor to major river flooding continues for parts of Southeast
Texas, particularly along portions of the Trinity, San Jacinto, and
Navasota rivers. The following river points are either at or
forecast to go into Moderate or Major flood stage as of Tuesday
afternoon:

- Trinity River (Liberty): Major Flood Stage
- Trinity River (Goodrich): Major Flood Stage
- Trinity River (Moss Bluff): Major Flood Stage
- Trinity River (Crockett): Rising to Moderate tonight
- Trinity River (Riverside): Moderate Flood Stage
- East Fork San Jacinto (New Caney): Moderate Flood Stage
- Navasota River (Normangee): Moderate Flood Stage

Remember to heed any instructions from your local officials and to
never travel through 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 continues.

Also of note is that the downstream runoff from the previous
rainfall will cause continued rises along the Brazos River through
the end of the week. The Brazos River at Sugar Land, Rosharon, and
West Columbia are forecast to rise into minor flood stage at the end
of the work week and through the weekend.

24/Luchs

&&

.CLIMATE...
Issued at 407 AM CDT Wed May 8 2024

Two record high minimum temperature records for the date of May 7
were at least matched in the Houston area yesterday. The City of
Houston record high minimum for the day was tied at 77. This
matches the old record from 2002. At Hobby, the record for the
highest minimum temperature for the date was broken. The low of 78
bested the old record of 77 degrees from 2003.

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)  90  73  90  66 /  10  10  30  20
Houston (IAH)  90  75  90  71 /  10  10  20  20
Galveston (GLS)  84  75  86  73 /  10  10  10  10

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...High Rip Current Risk until midnight CDT tonight for TXZ436>439.

GM...Small Craft Should Exercise Caution until 4 PM CDT this
     afternoon for GMZ370-375.

&&

$$

SHORT TERM...Luchs
LONG TERM....03
AVIATION...24
MARINE...03