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Area forecast discussion
National Weather Service Houston/Galveston Texas
1016 am CDT Fri Sep 22 2017

Discussion...
visibilities have improved across most of the dense fog advisory
area, so allowed the npw to expire on schedule. The rest of the
day looks much quieter than yesterday as some drier air edges into
the area from the northeast. 42
&&

Climate...
through the first three weeks of the month...

-College Station had an average temperature of 79.4 degrees (1.9
degrees below normal) and a rainfall total of 0.22 inches (2.03
inches below normal)

-Houston Intercontinental Airport had an average temperature of
79.0 degrees (1.9 degrees below normal) and a rainfall total of
0.98 inches (1.99 inches below normal).

-Hobby Airport had an average temperature of 81.5 degrees (0.3
degrees above normal) and a rainfall total of 3.16 inches (0.71
inches below normal)

-Galveston had an average temperature of 82.6 degrees (right at
normal) and a rainfall total of 0.01 inches (4.51 inches below
normal). Galveston's drier September on record is 0.04 inches set
in 1924.

42
&&

Previous discussion... /issued 626 am CDT Fri Sep 22 2017/

Aviation...
have had to hit this morning's fog a little bit harder north of
Houston as cxo has crashed to vlifr for visibility. Cll and uts
have shaded a little more to low stratus, dropping to LIFR on
ceilings, and only MVFR/VFR vis. Farther south, am trying to be a
bit more optimistic, holding at VFR. Despite not seeing it in the
obs yet, kept the MVFR tempo at sgr given visibility at
surrounding sites. Similar story at lbx - its ob has been missing
for a couple hours now, but given its propensity to fog up, will
leave in the fog tempo.

Expect improvement back to VFR mid to late morning as mixing
deepens. Short range models aren't enamored of rain chances today,
and satellite/obs show the best moisture plume to our south.
Despite this we still have a decent environment, albeit less
impressive than past days, and so will leave afternoon vcsh in
place for isolated to scattered showers today. Overnight, expect
conditions to be generally similar to tonight's conditions.

Luchs

Previous discussion... /issued 405 am CDT Fri Sep 22 2017/

Discussion...
so the calendar says its fall and we all know that means
absolutely nothing in southeast Texas. It is still humid as a sauna and
morning temperatures are in the 70s with areas of fog. At least we
did not have any record high minimum temperatures yesterday.
After yesterday's isolated heavy rainfall fall and flash flooding,
today should be on the dry side comparatively speaking. Axis of
higher moisture seen in GOES 16 derived precipitable water imagery
has become oriented over the western portions of the area and
into central Texas. Upper level pattern remains rather amplified
with a large long wave trough west of The Rockies, ridging through
the central U.S. And then weak troughing over the Carolinas and
southeast U.S. With the moisture axis moved west and perhaps a bit more
sinking motion from the ridge, best rain chances today will be
from Bay City to Columbus westward. There still could be some
isolated showers across southeast Texas but far less coverage than
yesterday.

The weekend forecast remains rather unchanged with mainly 20/30
pops each day. The upper level pattern remains amplified with the
trough over The Rockies but the ridge completely breaks down with
the trough over the Carolinas retrograding towards the Mississippi
River valley. Moisture also increases Sunday into Monday so expect
slightly higher rain chances each of those days, but coverage
still looks isolated to widely scattered for showers and
thunderstorms.

On Monday the upper level trough begins to transition east with
one piece of vorticity moving NE towards the northern plains by
Tuesday night. Forecast models still have another upper level low
back over the Great Basin/Four Corners region by Wednesday. This
is also when a cold front pushes into North Texas with the
Canadian model faster with the front, GFS slower and European model (ecmwf)
somewhere between the two. The pattern becomes more supportive of
a cold frontal passage for the end of next week as a trough
develops over the plains with northernly flow aloft. Surface cold
front should push into the area late next Thursday into Friday.
Both the GFS and Canadian show quite a bit of rainfall during this
period with the European model (ecmwf) quite dry. Forecast will remain
conservative with 40 percent rain chances but would not be
surprised if the models continue to depict heavy rainfall with the
front. GFS is bringing precipitable water values of 2.3 to 2.5
inches into the area late Thursday into Friday just as the front
arrives. Given the circumstances of Harvey, I really don't want to
forecast heavy rainfall with this front, but this will be a
pattern to watch in the coming days. GFS in particular has right
entrance region of jet over southeast Texas along with a slow moving
850mb front that could support a deformation zone. Heavy rainfall
would be possible until next Saturday when the 850mb front pushes
through and trough axis swings east. On the other end of the
spectrum, the European model (ecmwf) is very dry and has a much stronger ridge
aloft that develops as the front pushes through with drier air
behind it. Again this is all out on days 7 through 9 of the
forecast so a lot will change especially with a transitional
upper level pattern. We just need to be diligent to keep up with
those changes in the models and not bite off on any one model run
at this time.

Overpeck

Marine...
near caution winds over parts of the Gulf waters are expected to
diminish slightly to more light to moderate onshore winds. These
winds are expected to persist into the middle of next week until a
front approaches the area. Scattered showers, with a few
thunderstorms, can be expected daily. Winds and waves will be
higher in the vicinity of any thunderstorms. The best chance for
storms over the waters will likely come in the very late night and
morning hours. Tides have been consistently running a few inches
to half a foot above norm, and this should be expected to continue
into the weekend, perhaps increasing a little more if wind
directions and speeds align more favorably.

Luchs

&&

Preliminary point temps/pops...
College Station (cll) 91 72 91 72 91 / 20 10 20 10 20
Houston (iah) 90 73 91 73 89 / 20 10 20 10 30
Galveston (gls) 89 79 88 79 88 / 20 10 20 10 30

&&

Hgx watches/warnings/advisories...
Texas...none.
GM...none.
&&

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