Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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867
FXUS64 KHGX 192354
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
554 PM CST Sat Jan 19 2019

.AVIATION...
VFR throughout period. Western high pressure nudging eastward will
slacken the offshore pressure gradient and weaken the north flow
to under 10 knots through the early Sunday morning hours. Weak
north flow through the day tomorrow will turn variable to calm
by the late afternoon as high pressure moves overhead. 31

&&

.PREV DISCUSSION... /ISSUED 350 PM CST Sat Jan 19 2019/

DISCUSSION...

Gusty post-frontal winds have been the feature of today`s weather
as skies have largely cleared in the wake of a cold front. Look
for these winds to diminish through the night and tomorrow, with
quiet weather continuing until Tuesday, ahead of another cold
front sweeping through the area Tuesday night. Another reinforcing
front may be possible late in the week.

NEAR TERM [Through Tonight]...

Observations show gusty northwesterly/northerly winds across the
area. Sustained winds this afternoon range from 15 to 30 mph, with
gusts as high as 40 mph on Galveston Island. While we are likely
near the peak winds this afternoon, it will take until this
evening for winds to diminish enough to let today`s wind advisory
go for most, and strong winds are expected to continue well into
tonight at the coastline and on barrier islands.

On these winds, colder air is surging into the region. Freezing
temperatures are expected tonight for all but the coast, with lows
below 30 degrees forecast north of Houston. Fortunately, it
appears that the coldest post-frontal air will have moved off to
the east before sunrise, which should largely prevent hard freezes
in our area, though that potential cannot be totally ruled out
north of Huntsville.

SHORT TERM [Sunday Through Monday Night]...

Despite the cold start, clear skies will allow for some fair
heating Sunday, with high temperatures around or a little bit
above 50 degrees for the large majority of the area. Of course,
the flip side to that as the lack of clouds carries into Sunday
night will make for another chilly night into Monday morning.
Fortunately, winds do look to be veering relatively quickly, which
will arrest the fall of temperatures. A brief bout of freezing
temps may be seen again north of Houston, but as onshore flow
kicks in towards dawn, we may not see temperatures fall out of the
40s near the coast.

LONG TERM [Tuesday Through Saturday]...

Of course, a quick shift from offshore flow to onshore flow
frequently signals the development of new low pressure to our west
and another cold front incoming, and this situation is no
different. Lee cyclogenesis looks to occur in SW Colorado, dive
down to the Panhandles, then begin to eject towards Missouri on
Tuesday as an upper trough drops off the Rockies. Most models at
least suggest some light streamer showers cropping up on Tuesday -
not sure we`ll have enough moisture to pull this off, but between
that and uncertainty in frontal timing, have gone ahead with
chance PoPs near the coast. The best potential for rain will come
a little bit later as the front attached the aforementioned low
swoops in. The best upper forcing looks to be to our
north/northeast, but with a strong low level jet bringing in some
solid Gulf inflow into the frontal zone, that seems enough to
bring at least some light to moderate rainfall to the area Tuesday
night into Wednesday. The NAM doesn`t really agree, but there`s
pretty strong agreement among the globals, so we`ll shade that
way.

Temperature-wise, this pattern of course means we`ll see warming
Monday and Tuesday ahead of the front, with cooler temperatures
in the back half of the week. This may be bolstered as high
pressure and arctic air surge into the Central/Eastern US behind a
reinforcing cold front. The Euro in particular is really
aggressive, with nearly -30C 850mb temperatures at Green Bay on
Friday. The good news for us is that GRB`s longitude is already
east of us here in Southeast Texas, and it appears for now that
the coldest air will miss us to the east. So...while the late week
does look chilly again, I`m not really expecting us to see any
brutal cold...or even a return of temperatures we`re facing
tonight.

AVIATION [18Z TAF Issuance]...

High pressure continues to build into the area with strong gusty
northwesterly winds beneath a SCT-OVC MVFR deck near 2700-3500
feet. This deck of clouds should erode from the west and northwest
this afternoon and by 21z should probably only still clip UTS.
Winds diminishing from the 18-25G24-34kt this afternoon down to a
more constant 9-15kt around sunset with SKC. Stronger winds near
the coast should be the slowest to come down overnight/early
Sunday. Sunday looks to be VFR with N-NE winds 5-15 knots
diminishing through the afternoon.
45

MARINE...

Gale warning continues for the UTCW bays and offshore through 6 pm
for the bays and midnight Gulf waters. SCA kicks in after the Gale
wanes. Gradient should support at least wind gusts of gale. Seas
still building and then should start coming down after midnight as
well. Low water advisory in effect and will likely see it most
pronounced between 10 pm and 5 am with a fast drop initially on the
outgoing tide.

After this high pressure slides by quickly which in turn brings back
easterly/southeasterly flow and strengthens quickly likely back to
needing a SCA Tuesday prior to the next cold front. The next front
could arrive on the coast as early as midnight to 3 am Wednesday or
more likely 3 am to 6 am. SCA again in the wake of the front.
45

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      29  52  35  63  55 /   0   0   0   0  10
Houston (IAH)              30  52  36  63  57 /   0   0   0   0  10
Galveston (GLS)            36  50  46  61  59 /   0   0   0   0  10

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Wind Advisory until 6 PM CST this evening for the following
     zones: Austin...Brazos...Burleson...Chambers...Coastal
     Brazoria...Coastal Galveston...Coastal Harris...Coastal
     Jackson...Coastal Matagorda...Colorado...Fort Bend...
     Grimes...Houston...Inland Brazoria...Inland Galveston...
     Inland Harris...Inland Jackson...Inland Matagorda...
     Madison...Montgomery...Northern Liberty...Polk...San
     Jacinto...Southern Liberty...Trinity...Walker...Waller...
     Washington...Wharton.

     Wind Advisory until 10 PM CST this evening for the following
     zones: Brazoria Islands...Galveston Island and Bolivar
     Peninsula...Matagorda Islands.

GM...Low Water Advisory from 11 PM this evening to 6 AM CST Sunday
     for the following zones: Galveston Bay...Matagorda Bay.

     Small Craft Advisory until 11 PM CST this evening for the
     following zones: Galveston Bay...Matagorda Bay.

     Gale Warning until 6 PM CST this evening for the following
     zones: Galveston Bay...Matagorda Bay.

     Small Craft Advisory from midnight tonight to 6 AM CST Sunday
     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...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.

     Gale Warning until midnight CST tonight 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...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.

&&

$$

Discussion...33
Aviation/Marine...31



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