Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 220227
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
927 PM CDT Sat Oct 21 2017

.DISCUSSION...
Cold front is through the Panhandle this evening and is timed to
reach our far northwestern forecast area around sunrise tomorrow.
Lines of showers with embedded thunderstorms will likely begin
feeding into the downstream/pre-frontal trough as the main boundary
reaches the I-35 corridor shortly after midnight. Under a capped
downstream environment expecting late night lowering cloud heights
...a passing light shower and weakening winds as the front moves
into and across central Texas. Expecting the bulk of the TSRA to
reach the northern CWA during the overnight Sunday morning hours
...Houston metro a couple of hours after sunrise and across the
coastal counties during the mid to late morning hours. The main
front is forecast to pass off the coast early Sunday afternoon
with morning precipitation quickly coming to an end...gusty
northwesterlies and clearing skies the main theme Sunday afternoon.
In the maritime...Sunday night/Monday morning Advisory level
northerlies to blow across coast/upper Texas Gulf waters. Backing
high pressure to move into eastern Texas through tomorrow night/Monday
morning. 31

&&

.PREV DISCUSSION... /ISSUED 625 PM CDT Sat Oct 21 2017/

AVIATION...
Most terminals should see fairly benign conditions this evening.
MVFR cigs should eventually fill in around/after midnight.
Attention turns to north Texas where a line of showers and
thunderstorms associated with a southward moving cold front
approaches northern parts of se Tx around 10z and off the coast by
18z. Best estimated timing will be reflected in the TAFs. Primary
threat with the storms will be gusty winds and brief heavy
downpours. Ceilings will lift and gradually clear out during the
late morning and afternoon hours leaving mclear conditions and
gusty nnw winds during the daylight hours (also at night near the
coast).  47

&&

PREV DISCUSSION... /ISSUED 319 PM CDT Sat Oct 21 2017/
Warm and gusty this afternoon with a few showers and isolated
thunderstorms from around PSX-ARM-66R-DWH-6R3. These should
continue to expand slowly inland but will be fighting some capping
around 700-750mb per AMDAR soundings. Closer to the LLJ axis
scattered showers ongoing northwest of Caldwell and College
Station. Cold front has moved through Amarillo and as it pushes
southward expect storms to become more numerous across NTX
tonight. Front pushes into the CWA near College Station around 4-7
am Sunday and Houston around 6-10 am and Galveston 9 am-1 pm.
Timing differences still abound in the models hence the 3-4 hour
time windows for the FROPA. The environment supports a swath of
storms along and ahead of the from with an erosion of the cap and
little to only modest shear. Expecting a multicellular nature to
the storms with rainfall of 0.25 to 2 inches for the most part. As
the storms get down closer to the coast and into the nearshore
waters the wind gust potential gets higher and could see some
gusts of 25-40 mph with the storms. Quick drying by mid afternoon
across the area and temperatures only reaching the upper 70s to
lower 80s inland and lower to mid 80s (depending on frontal
timing-if it is slower then temperatures across the southern 2
tiers of counties will need a boost of 2-4 degrees) along the
coast.

Dry weather follows with persistent Sunday night through Monday
afternoon. Cool morning Monday in the upper 40s to mid 50s. High
pressure builds and should drift over the area early Tuesday
morning relaxing winds and allowing temperatures to again fall to
a respectably cool lower to mid 50s (these are near the
superblend/regblend but with excellent radiational conditions
present will probably need to go a little lower). Next upper
trough drops down in NW flow aloft and quickly swings a
reinforcing cold front through the area Tuesday late morning/early
afternoon with gusty northerlies. Noticeably drier air with this
one so no precip expected and with a few days of dry northerly
flow will begin to edge up the fire danger into elevated
conditions for the available dry fuels. Pleasant weather otherwise
Tuesday through Thursday with a deepening upper trough taking
shape Friday-Saturday over the Northern Plains into the Great
Lakes which should push another cold front through the SETX region
Friday afternoon-Saturday morning bringing a chance of showers
and thunderstorms back into the forecast. 45

&&

MARINE...
After a day of light to moderate winds over the waters, look for
moderate to strong onshore winds to return this evening. The winds
will be marginal for SCEC conditions, but holding off for now as the
ambient gradient looks to slacken a bit, which would limit the
nocturnal bump up in winds. Of course, tides will continue to be an
issue with the long onshore fetch, but do not expect high tide
tonight to be quite as problematic as last night - high tides will
not be an issue once the front goes through. Thunderstorms can be
expected with the front, bringing locally high winds and waves.

Once the front is through, offshore winds may push some water out of
shallow areas. At this time, it appears these winds may not be
strong enough or at quite the right angle to necessitate a low water
advisory. This will have to be watched, however, as stronger winds
and/or a more favorable wind direction could cause issues.

Speaking of those offshore winds, they look to reach to at least
near small craft advisory thresholds, and an advisory may be needed
for tomorrow night before diminishing on Monday. This lull may only
be brief, with the potential for caution or advisory-level winds
returning Tuesday into the mid-week, and then again late in the week
ahead of another cold front.  Luchs

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      70  79  49  80  55 /  70  70  10   0   0
Houston (IAH)              74  82  55  78  57 /  40  90  10   0   0
Galveston (GLS)            77  82  63  76  65 /  20  70  10   0   0

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&

$$

Discussion...31/47



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