Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 240926
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
426 AM CDT Sun Mar 24 2024

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

.SHORT TERM...
(Today through Monday Night)
Issued at 241 AM CDT Sun Mar 24 2024

The short term forecast today features the "quiet day" and the
"active day", and it just so happens to be in that order. One more
day of fair weather today, with winds now onshore and expected to
establish themselves even more, increasing the flow of more humid
Gulf air into the region. These winds look to be fairly strong
today, with sustained winds rising into the teens, and gusts pretty
routinely up into the 20s. Occasional gusts to around 30 mph may be
seen, mainly west of Houston. This isn`t quite to a level where we`d
need a wind advisory, but it should be noticeably breezy.

So, while the weather will be fair, we should also expect more
clouds today than yesterday as moisture depth and quality is
increasing on these stronger onshore winds. Because of this, we can
probably expect temperatures pretty similar to what we saw
yesterday, but shave up to a few degrees off the top. At night,
we`re already seeing the impacts of the southeasterly wind and
increasing humidity. Temperatures are on track to fall only a little
below 60 degrees by early this morning, and lows tonight will be
stuck in the 60s.

Of course, a warm night is not the only thing to keep an eye on late
tonight into Monday. Late this afternoon, convection will initiate
far to our northwest off the dryline, and is expected to quickly
grow upscale into an organized, linear complex. This makes its way
across the state, and will eventually push across East and Southeast
Texas. The precise timing is still somewhat difficult -guidance
frequently struggles with the propagation of large, organized storm
complexes, as storm and mesoscale factors come to drive the event. I
first begin to increase PoPs along our northern border shortly after
midnight tonight, with likely PoPs emerging around 7 am. Texas is a
big state, so if I`m still thinking the line moves in towards the
latter part of the window. But when these lines decided they want to
get up and go, they can really go. Putting in some slight chances
after midnight seems like a reasonable hedge for this possibility.
My highest confidence in rain will be Monday morning - whether the
line is fast or slow, it will almost certainly be in the area during
this time. As for moving off to the east, a fast line could be
pushing off shortly after noon, while a slower line would linger
more towards the late afternoon.

Alright, so that covers timing, but what about intensity? Well,
things get a little fuzzy there, too. Instability looks like it`s
going to be a real big question. Influx of warm, humid Gulf air near
the surface will be a boon, and as an upper trough pushes into the
state, heights aloft do look to be falling. But this will be
mitigated by plenty of cloud cover, and timing that will likely miss
the peak of daytime heating. HREF mean CAPE is in the 500-1000 J/kg
range, which is definitely enough for thunderstorms, and could
support severe weather, but it`s not ideal. Even the HREF max CAPE
shows only a relatively small patch exceeding 1000 J/kg. Taking a
different perspective, while managing 500 J/kg of CAPE is likely,
with an HREF probability in the 50-65 percent range, reaching 1000
J/kg is more of a 1 in 3 or 1 in 4 proposition. This ceiling on
instability probably provides a ceiling on storm intensity as a
whole.

Shear, on the other hand, will be around in spades. Mean HREF bulk
shear numbers are in the neighborhood of 50-60 knots with the line
moving through, well beyond any thresholds to support organized
convection. But even here, this introduces some questions. With
instability somewhat limited, it could cause an imbalance between
CAPE and shear, which would tamp down peak storm development. It
could also hamper line longevity by tearing apart new updrafts
before they really get going, making the line more difficult to
sustain. Getting a little more into specifics, this shear looks
largely line and boundary-parallel. Shear oriented in this way makes
the linear storm mode extremely obvious. It will also pound out a
long, straight hodograph, minimize concern for tornado potential and
shifting the focus more towards straight line winds. This isn`t to
say tornado potential is zero - storm scale dynamics can sometimes
present small segments that are locally more normal to the shear
vector, and a brief tornado could spin up.

All in all, the marginal risk (threat level 1 of 5) that SPC
presents for the eastern half of our area seems entirely
appropriate. If I were to rank my severe concerns for this line, it
would go as follows:
- Gusty to damaging straight line winds: If any storms get strong
enough, the environment clearly favors strong wind gusts.
- Tornadoes: This is a distant second place, at that. The broader
environment strongly disinclines tornado formation. Only if  severe
storms develop, and a small portion of the line find a  way to
locally take advantage of the shear profile would any  brief tornado
threat emerge.
- Hail: We just aren`t going to have the instability to get updrafts
capable of producing large, damaging hail. Maybe some small stuff in
the very strongest cells.

SPC`s attention is rightfully to our northeast for this event, where
a more favorable environment exists. Our threats are more
questionable and conditional. Most should expect rain, some
thunderstorms with gusty winds, and that`s about it. But don`t sleep
on the storm potential, either. The severe threat is greater than
zero, and still considerably higher than any given day. It just
doesn`t need to be an overwhelming concern for your day. Keeping
weather aware and able to receive weather warnings will be the key
actions.

&&

.LONG TERM...
(Tuesday through Saturday)
Issued at 241 AM CDT Sun Mar 24 2024

Relatively nice weather is expected in the wake of Monday`s
system. The mid/upper levels will feature persistent troughing on
Tuesday-Wednesday, helping to keep temperatures near to slightly
below normal. Afternoon temperatures are not expected to warm out
of the 60s in our northern counties while areas farther south
average in the low 70s. Overnight lows are expected to range from
low/mid 40s across our CWA`s north to around 50 in Houston and mid
50s at the coast. Still monitoring the prospect for PVA being
introduced over our region on Wednesday along with mid/upper
moisture. We continue to keep PoPs out of the forecast on
Wednesday due to LL dry air. But the forecast does feature
increased cloudiness. Beyond Wednesday, the mid/upper pattern
switches to a ridging regime. Meanwhile, LL flow will gradually
veer onshore on the backside of an eastward progressing high. This
will trend both temperatures and dew points slowly upward. By
the weekend, inland temperatures could be warming into the
low/mid 80s (70s at the coast) with overnight lows struggling to
drop below the 60s.

Self


&&

.AVIATION...
(06Z TAF Issuance)
Issued at 1200 AM CDT Sun Mar 24 2024

No major changes for latest TAF cycle. VFR conditions expected
to prevail through the period. Winds are variable with a generally
southerly component. Gusty conditions will develop shortly after
sunrise tomorrow morning. Sustained winds will increase to 15-20kts
with gusts as high as 30kts possible at times. Moderate to strong
onshore winds will bring an increase in moisture that will consequently
lead to an increase in cloud cover. CIGs should remain VFR, but some
locations could border or briefly touch MVFR later Sunday.  Adams

&&

.MARINE...
Issued at 241 AM CDT Sun Mar 24 2024

An increasing southeasterly fetch is expected today into tomorrow
ahead of an approaching front. Southeasterly winds are expected
to reach Small Craft Advisory criteria as early as the morning for
areas more than 20NM offshore. For the nearshore and bays, Small
Craft Conditions are expected by the afternoon. The elongated
fetch is expected to bring 6 to 10 foot seas tonight into Monday
morning. Showers and thunderstorms will be possible on Monday
along and ahead of the frontal boundary. Small Craft level seas
could linger into Monday evening. Lower seas and weaker northwest
winds are expected behind the front on Tuesday. Light to moderate
winds will veer to the northeast on Wednesday then southeast by
late Thursday into Friday.

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)  73  58  74  47 /   0  30  80   0
Houston (IAH)  75  66  76  53 /   0  20  80  10
Galveston (GLS)  72  67  73  60 /   0  10  50  10

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...Small Craft Should Exercise Caution from 7 AM CDT this morning
     through this afternoon for GMZ330-335-350-355.

     Small Craft Advisory from 4 PM this afternoon to 1 PM CDT Monday
     for GMZ330-335-350-355.

     Small Craft Advisory from 7 AM this morning to 4 PM CDT Monday
     for GMZ370-375.

&&

$$

SHORT TERM...Luchs
LONG TERM....Self
AVIATION...Luchs
MARINE...Self


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