Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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670
FXUS64 KHGX 181555
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
955 AM CST Sat Nov 18 2017

.UPDATE...
Another day of near `summer-like` conditions today ahead of strong
cold front currently pushing through central TX. Band of low
clouds has held ahead of the front over much of sern TX away from
the coast which will make max T forecasting challenging today as
strong SW winds continue to mix down. Expect daily record max Ts
will be in play for sites along and south of I-10 this afternoon,
while northern counties begin to see the strong cold front move
in. HRRR seems to have a decent handle on timing, which brings the
front through CLL/HSV areas by 19z/20z and into Houston and off
the coast by 23z. Gusty SW winds will become quite strong out of
the north behind the front.

All in all, only made cosmetic changes to near term conditions
based on observations.

JE

&&

.PREV DISCUSSION... /ISSUED 607 AM CST Sat Nov 18 2017/

AVIATION...
MVFR ceilings have developed at CLL, UTS, CXO, and IAH this
morning. Temporary impacts from MVFR will be also possible at HOU
and SGR before this stratus deck lifts to VFR by mid-morning. The
arrival of a strong cold front will result in breezy to windy
conditions both ahead of and behind this front. Southerly winds
ahead of the front are expected to veer to the west this morning
and increase into the 10-15 knot range with stronger gusts
approaching 25 knots. Isolated SHRA will be possible along the
front (namely near SGR/HOU/LBX/GLS where convergence along the
front will be greater), but have left mention out of TAF due to
anticipated low coverage. Expect the front to reach CLL by 18Z,
the Houston terminals by 21Z, and GLS by 00Z. Strong northerly
winds will persist behind the front tonight at the inland
terminals before decreasing below 10 knots by sunrise as surface
high pressure builds into the region. Winds will be higher at GLS
and persist longer, with 20-25 knot sustained winds gusting to
near 30 knots overnight.

Huffman

MARINE... Moderate to strong onshore flow will persist across the
offshore coastal waters this morning, before weakening during the
midday and afternoon hours as a strong cold front approaches.
Strong offshore flow will become established behind the front as
it pushes off the coast tonight with a thin band of showers
possible along the front as it sweeps across the waters. Frequent
gusts near gale force are expected tonight given the thermal
gradient behind the front and anticipated mixing of stronger gusts
above the surface (near surface winds of 35-40 knots) in response
to the warm coastal waters. Waves will also build accordingly
with 4 to 6 feet seas nearshore and 7 to 9 feet seas offshore.
Elevated winds and waves are expected to subside by late Sunday as
surface ridging slides across the Gulf Coast states.

Light northeasterly winds will gradually become onshore by Tuesday
ahead of the next cold front moving into the waters late Tuesday or
Wednesday, with another round of caution or advisory flags possibly
needed in its wake.

Huffman

FIRE...
Elevated fire weather conditions will be possible on Sunday behind a
strong cold front as drier air results in minimum relative
humidities falling below 30 percent. Morning 20 ft winds around 5-10
MPH inland and 10-15 MPH along the coast should decrease through the
the day Sunday, but are expected to overlap with drier conditions
long enough to produce at least a brief window for increased
concerns (especially along the coast where higher winds are
expected). Keetch-Byram Drought Index values along the coast have
increased into the 500-600 range, indicative of dry conditions that
may aid in fire starts in finer fuels like grasses.

Huffman


&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      80  43  64  41  66 /  20   0   0   0   0
Houston (IAH)              86  46  66  43  66 /  20   0   0   0   0
Galveston (GLS)            83  54  64  54  67 /  30  10   0   0  10

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Wind Advisory from 6 PM this evening to 6 AM CST Sunday for the
     following zones: Brazoria...Chambers...Galveston...
     Jackson...Matagorda.

GM...Small Craft Advisory from 6 PM this evening to 9 AM CST Sunday
     for the following zones: Galveston Bay...Matagorda Bay.

     Small Craft Advisory from 6 PM to 9 PM CST this evening 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...Waters from Freeport to the
     Matagorda Ship Channel from 20 to 60 NM...Waters from High
     Island to Freeport from 20 to 60 NM.

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

     Gale Warning from 9 PM this evening to 9 AM CST Sunday 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...Waters from Freeport to the
     Matagorda Ship Channel from 20 to 60 NM...Waters from High
     Island to Freeport from 20 to 60 NM.

&&

$$



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