Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 310440

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1140 PM CDT Thu Mar 30 2023

...New AVIATION...

(This evening through Friday Night)
Issued at 400 PM CDT Thu Mar 30 2023

A 35 knot LLJ is expected to strengthen overnight as a surface low
deepens over the Rockies/Central Plains. This will increase moisture
advection across the region as PWs near 1.4-1.6 inches. Forcing from
the LLJ and shortwave energy from a mid to upper trough over the
Four Corners/Rockies will tap into this ample moisture, bringing
isolated showers late tonight through the early morning hours of
Friday. Dewpoints will be in the upper 60s/lower 70s across the
region with lows in and around that same range, approaching and
potentially breaking record high minimum temperatures.

The aforementioned mid to upper level trough is expected to fill
across the the Central/Northern Plains on Friday. The 850mb jet
should strength to 40-50 knots during the mid morning/afternoon,
bringing breezy conditions at the surface and gusts near 25-30
knots. These low level winds will also veer southwesterly during
this time frame, which should improve heating and scatter cloud
cover through the afternoon. A mid level ridge over the Gulf of
Mexico will strengthen to 590 dam on Friday, while 850mb
temperatures climb to 14-17C. These factors will work to bring highs
in the mid to upper 80s inland and lower 80s along the coast.

A cold front associated with previously mentioned upper trough will
approach the Brazos Valley late Friday afternoon/Friday evening.
Forecast soundings still keep the environment capped during this
time frame, though daytime heating should put a dent in the cap`s
strength, enough to potentially get isolated showers/storms ahead of
the front. ML CAPE ranges from 800-1500 J/KG across the region with
3km SRH reaching 100-200 J/KG during this late afternoon period.
DCAPE peaks at 900 J/KG with wind profiles oriented along the
boundary. The front should enter SE Texas after sunset, so any
showers/storms associated with it won`t have as much instability to
tap into. Bearing this in mind, SPC currently has portions of the
Brazos Valley/Piney Woods area under a marginal risk of severe
weather for Friday. Strong, damaging winds will be the main threat
from these storms, though hail cannot be fully ruled out either.

Showers and storms should diminish by midnight as the front
approaches the coast. Lows will be in the lower 50s to upper 60s.


(Saturday through next Wednesday)
Issued at 400 PM CDT Thu Mar 30 2023

Saturday morning should see the surface front just beyond the
coast, though some lingering elevated rain might be possible with
along the frontal surface just aloft. My confidence here isn`t
quite high enough to keep any mentionable chances in place
Saturday morning, but technically the rain chances are greater
than zero...just not very much greater.

I do cut temperatures a little bit this weekend, particularly well
inland with the briefest and slightest bit of low level cold
advection on Saturday. However, the incoming airmass will also be
drier, and at least on Saturday, a sunnier don`t expect
a big cut in high temps this weekend. On top of that, at Galveston
the onshore flow will advect continental air over the Island,
which frequently overrides the moderating effect of Gulf water

By Sunday, the surface high drifts over the Southeastern US, while
ridging aloft remains the name of the game. So yup, you guessed
it! The first part of next week means a big warmup and a note from
the atmosphere that summer is coming (imagine a dour looking guy
sitting on a throne with a sword, but wearing flip flops, shorts,
and a linen shirt). Sunday will be the "cool" day - and by that, I
mean slightly above the seasonal averages in the upper 70s to
around 80. From there, we could really turn the torch on for a
couple days. Just how hot it gets will depend strongly on how much
low level flow veers, as increasingly southwesterly flow will
probably turn the torch up hotter. More backed flow will have a
moderated influence from the Gulf, and be merely "not quite as
above average".

What I do have high confidence in is that temperatures in the
deterministic NBM dataset are way too strongly corrected
downwards. Both highs and lows early next week are in the 10th to
25th percentile in the NBM distribution, and at Galveston,
frequently fail to even reach the "high" bar of the 10th
percentile. Given that this is a scenario in which numerical
guidance fairly routinely fails to get hot enough, this seems to
be the wrong direction. For now, I go with an even blend of the
median NBM and its deterministic numbers. Using the deterministic
numbers at all is a nod to the potential that things may not get
quite as hot with more backed flow.

I do suspect, however, that the warmer solution is probably the
way to go here. In a multi-model cluster analysis (including the
Canadian, GFS, and Euro ensembles), the dominant cluster is one
close to the ensemble mean, or a little warmer. The NAEFS and EPS
mean 850 temps exceed the 90th and sometimes the 97th percentile
in this window. Though I am a bit wary of numbers from so close to
the surface, there are even some 1000 mb temps exceeding the
99th percentile in these ensemble means. And that`s the means, not
even the high end of the distribution! The EPS extreme forecast
index continues to show an increasing confidence in abnormally
high temperatures in this period, with EFI values exceeding 0.7
(on a scale of 0 to 1) for abnormally high temperatures. Though
at least the shift of tails doesn`t necessarily indicate a high
amplitude extreme, "merely" a high confidence in an extreme.

Mid-week will bring another frontal passage, and our next chance
at showers and storms, plus some cooler temps. Frontal timing on
Wednesday will be extremely important to high temperatures, and
there`s big bust potential there. Given the current consensus that
the front won`t quite reach the coast fast enough to chop off
temps, I sharpened NBM to be hotter at the coast and cooler inland
to match that timing. This is in keeping with a lingering signal
for high temps at the coast in the above mentioned ensemble data
on Wednesday. Beyond that, given the broad model uncertainty, I
hewed much closer to the deterministic NBM numbers for the late
week. I do still have a bit of concern that it`s pushing temps
down a little too much...but it does not appear as out of step
with the meteorology late in the week, as it does accurately
capture the mood in the models to show a pattern shift to a
cooler, rainier pattern.


(06Z TAF Issuance)
Issued at 1132 PM CDT Thu Mar 30 2023

MVFR with occasional IFR ceilings are expected overnight through
mid/late Friday morning. A few disturbances will continue to
develop/move NNE in the next few hours, resulting in VCTS mainly
around CLL and UTS. Ceilings should slowly improve by midday
Friday with SCT MVFR to BKN VFR conditions in the afternoon.SE to
S winds will continue to bring low to mid-level moisture across
the region in advance of the next cold front that will enter the
region by late Friday afternoon. This FROPA will also result in
gusty winds and scattered showers and storms along the boundary.



Issued at 400 PM CDT Thu Mar 30 2023

Winds, particularly gusts, remain in a 15 to 20 knot range on the
waters, prompting continued caution flags through the evening and
into the late night hours. Additionally, seas remain around 5 to
6 feet on the Gulf waters. Caution flags may need to be extended
deeper into the day on Friday. Moderate and gradually veering
winds are expected through Friday night.

Much weaker winds are expected by Saturday, and near shore, winds
may even become briefly offshore as a weak front dissipates near
the coast. However, increasing onshore flow is expected to return
by Sunday into Monday. Expect increasing winds deeper into the
week ahead of the arrival of the next cold front and another
opportunity for active weather.


College Station (CLL)  71  88  55  82 /  20  40  40   0
Houston (IAH)  72  88  65  89 /  20  20  20   0
Galveston (GLS)  71  80  70  81 /  10  20  10   0


TX...High Rip Current Risk until 10 AM CDT Friday for TXZ436>439.

GM...Small Craft Should Exercise Caution until 4 AM CDT Friday for



LONG TERM....Luchs
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