Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS64 KHGX 181745
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1145 AM CST Sat Nov 18 2017

.AVIATION...
Cold front was moving through the Interstate 35 corridor west of
the area at 1730Z. Tweaked the timing a bit--an hour earlier. Main
impacts are ceilings and winds ahead of the front, and then winds
following the frontal passage. The MVFR conditions were lifting
at 17Z. These could linger for a couple an hour or two but VFR
should be common by 20Z. Southwesterly winds were already gusting
ahead of the front. The frontal passage should see winds become
northwest and gust to between 20 and 25 knots over the inland
areas at least for three or four hours before slowly diminishing.
At the coast gusts to over 30 knots are likely after 03Z at KGLS.
These should diminish after 14Z Sunday morning.

A side note is that an isolated shower could develop mainly from
the metro Houston sites to the coast along and ahead of the
frontal passage. Chances were too slight to include in the
forecasts.

40

&&

.PREV DISCUSSION... /ISSUED 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/

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.

&&

$$

Discussion...48
Aviation/Marine...40


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.