Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 242337
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
537 PM CST Tue Jan 24 2017

.AVIATION...
Elevated southerly winds 10-15 knots with stronger gusts
approaching 20 knots will continue for the Southeast Texas
terminals this evening ahead of a cold front approaching from the
northwest. Moisture return ahead of this front will result in the
development of MVFR ceilings at the terminals by 03-06Z, with
enough surface convergence along both a prefrontal trough and the
actual cold front to result in the development of light SHRA near
the terminals after 07Z. High resolution guidance is advertising
IFR to even LIFR ceiling development along and ahead of the cold
front, but forecast soundings show low level winds remaining
elevated (25-30 knots) during this time and concerned that too
much mixing will occur for stratus to build down this low. As a
result, have not included in TAF attm but will consider possible
inclusion for the 06Z TAFs. May also see some patchy fog
development ahead of the front after 07z as the surface pressure
gradient relaxes with the front`s approach.

Expect southerly winds to veer to the west with the prefrontal
trough and then northwest behind the front, with the front
clearing the Galveston 17-19Z Wednesday. Drier air behind the
front will allow for MVFR ceilings to lift/scatter back to VFR by
Wednesday afternoon.

Huffman

&&

.PREV DISCUSSION... /ISSUED 353 PM CST Tue Jan 24 2017/

DISCUSSION...
A relatively tight onshore pressure gradient between a central
Gulf high and lowering Panhandle pressures ahead of a developing
Rocky Mtn lee cyclone has kept PM regional southerlies near 15
knots. Couple this with a mid day cumulus deck beginning to form
over the coastal counties and there may be just enough mixing
occurring to keep many from reaching their record maximum
temperatures. Many T readings have achieved the lower 80s and
this enhanced onshore flow has increased dew points by a good 15
to 20 degrees today. A cold frontal passage tomorrow morning will
provide enough lift within a downstream (near) saturated lower 5
to 6 k feet to squeeze out early day scattered showers. The mid-
level warm nose should be stout enough to limit any precipitation
to just (lower QPF) early Wednesday showers. Patchy coastal fog
may form tonight and persist just ahead of the front. Temperature-
wise...this will be the last above normal day of the week as
cool/dry air advection kicks in through mid week `modifying`
diurnal temperatures to closer-to-30 year-normal values. Slightly
below normal minimum temperatures in the upper 30s to lower 40s
and maximum temperatures in the 60s will be the late week norm.
An early weekend reinforcing cold air mass will keep days in the
50s/low 60s...overnights in the upper 30s/lower 40s. Slight to low
extended period rain chances will exist over the Gulf per the
existence of lower pressures/offshore (near) surface trough. 31

MARINE...
Strong south winds in response to deep low pressure over the
central plains will persist into the evening. The gradient is
progged to relax as the low moves away. Will maintain the SCA
through 03z and may need to be extended a bit longer if winds
relax slower or seas remain high. Dew pts are a few degrees warmer
than the water temps so some patchy fg may be possible but surface
winds are south and will become southwest later tonight. This
trajectory is not favorable for fog so will only mention patchy
and that is probably overkill. A cold front will move through the
coastal waters early Wednesday and will shift to the W in the
morning and NW by afternoon. An SCEC will be possible by aftn over
the offshore waters. Sfc high pressure will be centered over TX on
Thursday. The orientation of the high will allow a brief period of
east winds ahead of a reinforcing cold front that will cross the
coastal waters early Saturday. A moderate to strong offshore flow
is expected for the remainder of the weekend. 43


&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      57  67  39  60  36 /  30  10  10   0   0
Houston (IAH)              65  73  43  61  39 /  30  20  10   0   0
Galveston (GLS)            65  72  51  60  50 /  20  30  10   0   0

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...Small Craft Advisory until 9 PM CST this evening for the
     following zones: Waters from Freeport to the Matagorda Ship
     Channel from 20 to 60 NM...Waters from High Island to
     Freeport from 20 to 60 NM.

&&

$$

Discussion...45
Aviation/Marine...14



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