Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 170004
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
604 PM CST Fri Feb 16 2018

.AVIATION...
A cold front evident on TIAH stretches from IAH to just north of
SGR this afternoon. Expect this boundary to continue translating
south towards HOU over the next 1-2 hours, resulting in a light
northerly wind shift. Weak convergence in the vicinity of the
front has been enough to produce a few light rain showers across
the Houston metro and have inserted a VCSH mention in for HOU and
SGR through early evening. Strengthening southwesterly flow 925
MB this evening may result in this frontal boundary stalling near
HOU and possibly lifting north towards IAH during the overnight
hours. Expect winds in the vicinity of the front to remain light
and variable overnight with terminals south of the frontal
boundary experiencing LIFR to IFR conditions as low ceilings and
fog develop.

Webcams show sea fog just beginning to enter the lower Galveston
Bay area and have delayed onset of lowered visibilities for GLS as
a result. As light southerly winds along the coast back ahead of
the front this evening, expect sea fog to overtake the terminal
with anywhere from VLIFR to IFR visibilities persisting through
midday.

Mixing south of the stalled boundary on Saturday should allow for
ceilings to lift to MVFR and scatter to VFR by the afternoon. A
secondary cold front entering the region on Saturday afternoon
will result in the development of isolated SHRA near CLL as it
begins to approach the terminals after 21Z.

Huffman

&&

.PREV DISCUSSION... /ISSUED 348 PM CST Fri Feb 16 2018/

DISCUSSION...
Weak front is slowly moving through the region. It should
gradually be losing support for a continued southward push this
evening and guidance continues to show it stalling somewhere
between I-10 and the coast overnight. It`ll probably meander
between Highway 59 and the beaches through Saturday night.
Although there`s not a lot of forcing, think there`s probably
enough llvl saturation and isentropic lift to maintain lowish POPs
in the fcst. Areas of dense sea fog will persist south of the
boundary. As lee side pressures fall, look for the stationary
front to head back north on Sunday.

The broad upper ridge that has been situated across the Gulf Coast
will make its way eastward and off the southeast U.S. coast early
next week as the next western trof digs southward. A more
pronounced southwest flow aloft will evolve going into midweek as
the eastern ridge expands northward and western trof southward.
Llvl s/se flow will increase thru the same time period as pressure
gradient tightens.

The next cold front will approach the area ~Wednesday next week.
With very little upper-level support for a continued southward
push, the front is likely to become stationary near the coast. This
type of pattern (blocking high to the east, trof to the west, sw
flow aloft transporting Pacific moisture and upper disturbances,
deep Gulf moisture in place, upper diffluence, and a stationary
boundary) has been known to be a prolific rain producer across the
area. We`re still a long way off--but just something we`ll be
keeping an eye on in the coming days. 47/22

MARINE...
A Dense Fog Advisory is currently in effect for the nearshore waters
this afternoon. Sea fog will likely roll back into the bays late
this afternoon into the evening hours, and a Dense Fog Advisory will
likely be needed once again for both Galveston and Matagorda Bay.
The development for sea fog will continue through the weekend, as
warm moist air remains situated over cooler shelf waters. Onshore
winds will pick up slightly Saturday morning in the offshore waters,
and the lingering frontal boundary will shifts northward through the
day Saturday. Surface high pressure will build into the area from
the north late Saturday into Sunday and winds will become easterly
by Sunday morning. Onshore flow will increase approaching SCEC
criteria Monday into Tuesday as a southeasterly fetch sets up across
the Gulf of Mexico. This will bring added moisture to the region,
through mid-week. Wave heights will also increase to between 3 to 5
feet. The next frontal boundary is forecast to reach SE TX next
Wednesday. Latest global guidance is showing the front stalling
before reaching the coast, which could hinder the clearing of sea
fog from the coastal waters.

Hathaway

$$

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      52  60  54  71  63 /  20  40  30  30  20
Houston (IAH)              59  70  57  73  64 /  20  40  30  30  20
Galveston (GLS)            63  70  60  70  65 /  20  30  20  20  20

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...Dense Fog Advisory until noon CST Saturday for the following
     zones: Coastal waters from Freeport to the Matagorda Ship
     Channel out 20 NM...Coastal waters from High Island to
     Freeport out 20 NM.

&&

$$

Discussion...11
Aviation/Marine...14



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