Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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060
FXUS64 KHGX 221740
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1140 AM CST Sun Jan 22 2017

.AVIATION...
An area of weak low pressure over Arkansas will pull east this
afternoon but some wrap around clouds will scoot across area TAF
sites. Clear skies expected tonight through the end of the TAF
cycle. W-NW winds will remain strong through 00z and then begin to
slowly decrease. Wind gusts this afternoon will exceed 40 knots at
times. Winds will likely remain strong near the coast through at
least 06z before decreasing. 43

&&

.PREV DISCUSSION... /ISSUED 1041 AM CST Sun Jan 22 2017/

UPDATE...
Strong northwest winds are kicking in this morning with the most
robust winds occurring across the northwestern CWA. Sustained 25
to 35 mph winds...with gusts to near 40 mph...will be commonplace
across the majority of the forecast area through the afternoon.
These strong winds...with lower relative humidities of around 30
percent...has prompted a Red Flag Warning for the western third
of the CWA. Quick drying fuels (e.g., grasses) counter the recent
rain that the region has received so...if wildfire were to occur
today...these high winds would rapidly spread fire southward.

The northeastern cloud cover wrapping around an eastern-exiting upper
low will thin out over the next hour...becoming mostly sunny with
cooler air regulating today`s warmth to the middle to upper 60s...lower
70s over our southwestern counties. Winds are forecast to die down
around sunset with evening temperatures falling into the lower to
middle 50s. 31


PREV DISCUSSION /Issued 420 AM CST Sun Jan 22 2017/...

NEAR TERM [Through Today]...
Surface and upper air analysis show a stacked low over Oklahoma
with 994mb at the surface. Pressure gradient continues to tighten
over much of Texas which should support strong gusty winds. KHGX
88D VAD wind profile showing 35kt WNW winds 1000 feet off the
deck so there should be some good 30 to 40 mph wind gusts once
mixing occurs. Drier air will also advect into the region and look
for dewpoint temps to drop to the low 40s with relative humidity
around 35 percent. Temperatures will be lower than yesterday with
the dry air coming into place. The main concerns for today will be
the gusty winds so the wind advisory looks on track for inland
areas along with the gale warning for the marine areas.

SHORT TERM [Tonight Through Tuesday]...
Overall there is not a lot of change in the short term forecast.
Upper level ridge will develop over Texas on Monday with the next
short wave trough moving into the central Plains on Tuesday.
Temperatures will look to increase under the influence of the
ridge and also see increasing 850mb temperatures on Tuesday.
During the day Tuesday 850mb temperatures increase to around
17-20C which support high temperatures back in the low 80s in a
few spots. This means that record high temperatures may be set
for places like Houston and Galveston.

LONG TERM [Tuesday Night Through Sunday]...
The forecast models have been pretty consistent with bringing a
cold front into the area Wednesday morning with a line of showers.
Moisture return Tuesday night should be enough with precipitable
water values getting up to around 1.3 inches. Instability may
creep up enough along the coast to need to mention thunderstorms.
Temperatures should be back in the 60s for high temperatures and
it looks like near normal temperatures for the end of the work
week. This means high temperatures in the low 60s and low
temperatures in the 40s.

The far extended range forecast for next weekend has changed a
bit from previous model runs. GFS/ECMWF both develop a similar
amplified pattern with a ridge over the west coast and a large
trough over the Great Lakes. This pattern usually sets up for a
couple more cold fronts and a short wave or two to rotate through
with northerly flow aloft. The ECMWF brings a short wave into the
area Saturday with a chance for showers while the GFS is not as
strong. GFS is stronger with a developing cutoff low over the
Desert SW and Baja, but both the GFS and ECMWF are similar in that
regard. GFS tries to develop a coastal trough in response to the
trough axis. This brings back rain chances for late Saturday into
Sunday. We`re not sure if this solution will pan out since there
will be quite a bit of vorticity stretching over the area and not
strong enough large scale lift for lowering pressures.

Overpeck

MARINE...
A stronger than expected pre-frontal trough has slowed the passage
of the main cold front a little bit tonight, but the gale warning
seems in good shape as is, as there is still a good burst of wind
along that trough - there just will likely be a short lull in winds
until the slower trough comes through with stronger winds again
before daybreak. Will continue to leave the gale warning as one
contiguous block for now, but the day shift will likely be able to
trim back in the bays and perhaps the nearshore waters before expiry
at 03Z Monday (9PM Sunday). Additionally, a low water advisory is in
place for Galveston Bay, as the strong offshore flow drives water
out towards the Gulf. While Morgans Point remains about a foot above
normal, there was a noticeable drop when the pre-frontal trough
moved through, and the rebound when winds went into a lull is
already starting to fade. This drop will accelerate rapidly, as is
already being seen around Galveston.

Beyond this event, winds and seas will diminish Sunday night and
Monday, when winds will flip back to onshore, and strengthen
Tuesday. SCEC seems likely, and a small craft can`t be completely
ruled out. Another cold front looks to move through Wednesday, and
though the guidance is not quite as bullish tonight as it has been
in recent days, small craft conditions are again a possibility.

FIRE WEATHER...

A strong cold front is crossing Southeast Texas tonight. West to
northwest winds are becoming strong and gusty in the wake of the
front, which will continue through Sunday. Recent rains have fuel
moisture values quite low to start, but significant drying in the
fine fuels is expected today as winds increase and RH values drop.
Min RH values are likely to range between 30 and 45 percent, and
when paired with the wind, expect grassy fuels to dry quickly.
Elevated fire weather conditions are likely on Sunday but the
antecedent wet conditions coupled with RH above critical values
precludes a Red Flag Warning. Per TFS Predictive Services, most of
the area will have low to moderate fire danger, but a small area in
Matagorda and Brazoria counties did receive a predicted fire danger
of high. RH values on Monday look modestly lower than Sunday as dry
air filters into the area, but winds also are likely to be at or
below 10 mph, mitigating concerns.

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      66  43  71  52  79 /   0   0   0   0  10
Houston (IAH)              69  45  70  52  80 /   0   0   0   0  10
Galveston (GLS)            67  52  67  60  76 /   0   0   0   0  10

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Wind Advisory until 5 PM CST this afternoon for the following
     zones: Austin...Brazoria...Brazos...Burleson...Chambers...
     Colorado...Fort Bend...Galveston...Grimes...Harris...
     Houston...Jackson...Liberty...Madison...Matagorda...
     Montgomery...Polk...San Jacinto...Trinity...Walker...
     Waller...Washington...Wharton.

     Red Flag Warning until 5 PM CST this afternoon for the following
     zones: Austin...Burleson...Colorado...Jackson...Matagorda...
     Washington...Wharton.

GM...Gale Warning until 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...Galveston Bay...Matagorda Bay...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...31
Aviation/Marine...43



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