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National Weather Service Forecast Discussion

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FXUS64 KHGX 212132
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
332 PM CST Mon Jan 21 2019

.DISCUSSION...

An active weather pattern continues, with a front expected
tomorrow night, another weak front Friday, and then yet another
front later in the weekend. Expect rain and (near the coast) an
isolated thunderstorm with the first front. Rain potential is a
little fuzzier with the next two fronts, but there looks to be at
least a slight chance of showers each time. None of the fronts
look to bring a deep blast of frigid air, but the series of fronts
should keep low temps in the northern third to half of the area in
the 30s with periodic light freezes, and in the 40s closer to the
coast. Look for Wednesday night to be the coldest, with a light
freeze managing to push a little south of I-10 in the exurban and
rural areas west of Houston.


.NEAR TERM [Through Tonight]...

We have some clouds around 2-3k feet in much of the area, thickest
nearer the coast. Though the radar may hint at some drizzle south
of Conroe, HRRR soundings are dry enough in the lowest km that
I suspect that none of it is reaching the ground. It might be nice
to be able to see some AMDAR soundings, but...the AMDAR site is
currently shut down.

Generally expect similar trends through the night, with increasing
clouds and as onshore flow boosts low level moisture, there will
be the chance for some drizzle, sprinkles, or even some light rain
showers later in the night. Of course, with inflow from the Gulf,
increasing dewpoints, and a cloudier sky, low temperatures will be
much up. In fact...tonight`s low may even exceed high temperatures
from our chilly weekend.


.SHORT TERM [Tuesday Through Wednesday Night]...

The chance for some streamer showers will be a little higher
Tuesday morning, and by afternoon, some higher rain chances look
to creep up in the far north as the cold front approaches.
But...the big show with rain on this front will come Tuesday night
on/just behind the cold front. Lift along the front won`t be
super vigorous and with a good chunk of the rain falling behind
the front, surface instability will be somewhat limited, but I
suspect we`ll manage to produce an isolated thunderstorm or two
along the front, while most see light to moderate rain. Around and
east of I-45, QPF totals are in the half-inch to an inch range,
while it looks to be more in the quarter to half-inch range
farther west.

One big question will be how long precipitation lingers into
Wednesday morning behind the front. We look to see a pretty decent
rush of colder air in behind the front, and if the front is early
enough for enough cooling...and the precip drags on long
enough...there`s a nonzero chance of seeing rain change over to
sleet or, more likely, flurries before coming to an end. Indeed,
some of my automated consistency tools sprinkled, isolated specks
of a tenth of an inch of snow accumulation in Houston County
(also see: WPC`s 1-5 percent chance of snow accumulation in the
same period). Right now, confidence is low enough that I opted to
tweak the forecast a bit so that snow no longer popped up. It will
be something to keep an eye on, though. I would expect that
impacts will be none to minimal at worst, so it would be mainly
conversational snow...and I`m not terribly interested in having
that conversation...just yet.

As for Wednesday and Wednesday night...well...remember Saturday
night and Sunday? If you enjoyed that, it`ll be another fun time
for you. Cold advection and clouds keeping Wednesday cold, with
clearer skies allowing for the chilliest night of the week on
Wednesday night. For the most part, any light freezes should stay
north of I-10, except in the rural areas well west/southwest of
Houston, where the northern chunks of Matagorda and Brazoria
counties might briefly touch 32 around dawn.


.LONG TERM [Thursday Through Monday]...

Things get a little warmer on Thursday with sunny skies and winds
that, if not really onshore, are no longer decidedly offshore
anymore. A weak reinforcing front looks to dip into the region
Friday as high pressure drops into Texas, and it may happen before
winds can even turn fully onshore. Because of this, rain chances
will be pretty low - in fact, I keep them even below a slight
chance mention. It`s not impossible especially as precipitable
water tries to bounce back a bit just before the front, but it
should just be too dry to get anything.

Looking into the weekend, a vort max looks to dump off the Rockies
and dig into the Rio Grande Valley before swinging across the
area. Additionally, a weak surface reflection looks to develop and
briefly pump some Gulf moisture into the area, then bring another
weak front through. The GFS is not super enthused with rain
potential, staying pretty dry. The Euro, on the other hand, is
surprisingly aggressive. Took a bit of a middle path with the
forecast and put in chance PoPs this weekend. I think the Euro is
too aggressive here, but as long as we can get decent enough
moisture return, we`ll have a shot at some showers.

With the rapid succession of fronts and not much time for
anomalously warm or cold airmasses to set up shop over Southeast
Texas, the temperature trends in the long term are not
particularly large at this point.

&&

.AVIATION [18Z TAF Issuance]...

BKN/OVC deck around 3000 feet and slowly rising has been streaming into
the area off the Gulf this morning, and anticipate this deck 3000-3500
feet) to continue to work its way further inland this afternoon. Decks
should lower tonight (1500-2500 feet) and persist tomorrow. Expect to
see some SHRA development beginning tomorrow afternoon with best coverage/
chances coming for most of the area tomorrow night in association with
the next cold front. Still expecting to see increasing SE/S winds this
afternoon with gusts >20 knots. Winds should lower tonight but remain
around or slightly above 10 knots. Might see some higher speeds develop
tomorrow morning and afternoon before coming down again with a relaxing
gradient.

Behind Tuesday night`s cold front, winds will shift to the NW and N
and increase to 15 to 20 knots and gusty with SHRA coverage gradually
decreasing from west to east Wednesday morning. 42

&&

.MARINE...

Caution flags (mainly nearshore waters) and Advisories
(mainly offshore waters) will be in effect through Tuesday
for strengthening onshore winds and building seas. We might
end up needing to upgrade some of our nearshore flags to
advisories. There might be a window Tuesday afternoon/evening
with lower winds/seas, but winds will be shifting to the north
and northwest after the passage of the next cold front late
Tuesday night through early Wednesday morning. Advisories
will be needed Wednesday behind the front for the strong
offshore winds (some gusts could approach gale force) and
building seas. A general lowering of winds and seas is
anticipated on Thursday followed by another rise and possible
flags Thursday night and Friday after the passage of another
cold front. 42

&&

.PRELIMINARY POINT TEMPS/POPS...

College Station (CLL)  55  69  36  49  32 /  10  50  70  40   0
Houston (IAH)          56  71  40  48  33 /  10  50  90  60   0
Galveston (GLS)        59  67  44  49  41 /  10  30  90  80  10

&&

.HGX WATCHES/WARNINGS/ADVISORIES...

TX...None.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION through Tuesday afternoon
     for the following zones: Coastal waters from Freeport to
     Matagorda Ship Channel TX out 20 NM...Coastal waters from
     High Island to Freeport TX out 20 NM.

     SMALL CRAFT SHOULD EXERCISE CAUTION from 6 PM CST this evening
     through Tuesday morning for the following zones: Matagorda
     Bay.

     Small Craft Advisory from 6 PM this evening to 6 PM CST Tuesday
     for the following zones: Waters from Freeport to Matagorda
     Ship Channel TX from 20 to 60 NM...Waters from High Island
     to Freeport TX from 20 to 60 NM.

     SMALL CRAFT SHOULD EXERCISE CAUTION until 6 PM CST this evening
     for the following zones: Waters from Freeport to Matagorda
     Ship Channel TX from 20 to 60 NM...Waters from High Island
     to Freeport TX from 20 to 60 NM.


&&

$$

NEAR TERM...Luchs
SHORT TERM...Luchs
LONG TERM...Luchs
AVIATION...42
MARINE...42

NWS HGX Office Area Forecast Discussion