Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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232
FXUS64 KHGX 200323
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
923 PM CST Thu Jan 19 2017

.UPDATE...
A few tweaks were made to the previous forecast to account for
latest observations. Fog has already begun to develop west of the
Houston metro and will only spread and get worse as the night
goes on. A Dense Fog Advisory may be required later tonight,
especially for areas that are still saturated from rainfall
earlier today.  11


&&


.PREV DISCUSSION... /ISSUED 553 PM CST Thu Jan 19 2017/

AVIATION...

Per satellite loops, drier air has moved into SE TX this afternoon
from the west but with limited mixing...these MVFR CIGS have stuck
around this evening. The combination of wet grounds/calm winds and
low T/TD spreads progged for tonight are all pointing to the deve-
lopment of widespread fog/low clouds overnight through Fri morning.
So did not make a lot of changes with the previous TAFS (which had
these trends). 41

PREV DISCUSSION... /ISSUED 334 PM CST Thu Jan 19 2017/

Rain from earlier this morning had cleared all but the eastern
offshore waters as of 3 PM CST, with dry conditions expected to
persist through the remainder of the evening and overnight hours
as subsidence in the wake of a closed low lifting across the
Central Plains overspreads the region. A few breaks in the clouds
this afternoon had allowed for temperatures to climb into the low
70s along the Upper Texas coast this afternoon, with most
locations reporting temperatures in the lower to mid 60s.

Increasingly westerly low level flow this evening and tonight
will help promote additional erosion of cloud cover this evening.
However, radiational cooling and recent rainfall across most of
the region will result in low clouds and patchy to areas of fog
development (some dense) by early Friday morning. Expect this fog
to lift mid to late morning.

Afternoon water vapor imagery shows another disturbance diving
across Arizona towards the region, with an associated right
entrance of a 130-140 knot upper level jet sliding over the
northwest Gulf by Friday afternoon. Increasing lift associated
with this feature will result in scattered to numerous showers and
thunderstorms blossoming along the Texas Coastal Bend and
spreading northeast along the Upper Texas Coast and possibly as
far north as the Interstate 10 corridor during the afternoon and
evening. Mean cloud layer winds around 45-50 knots will result in
this activity lifting across the region very quickly (minimizing
any flood threat), but cannot rule out some pockets of heavier
rain in stronger cells along the coast. Mid-level lapse rates
increasing to around 7-8 C/KM across the northwest Gulf Friday
evening and night may result in a large hail or damaging wind
threat materializing for the marine areas before the main upper
system kicks to the east by early Saturday morning. Otherwise,
morning temperatures in the mid 50s and low 60s are forecast to
rise into the mid to upper 70s by the afternoon tomorrow.

Shower and thunderstorm chances will linger into Saturday as
another upper disturbance reaches the region, with height falls
associated with this system inducing a surface cycling across the
Southern Plains. Increasingly diffluent flow aloft and low level warm
air advection will promote scattered shower and thunderstorm
development through the day Saturday, with a Pacific front being
dragged across Texas Saturday night as the surface low ejects
towards the Middle Tennessee Valley. Much drier air will filter
into the region behind this front, with an elevated surface
pressure gradient promoting sustained northwest winds in the 20-30
MPH range. Wind Advisories will likely be needed on Sunday. Highs
in the 70s with lows in the mid 40s to 50s are forecast this
weekend.

Dry conditions will persist through the middle of the upcoming
week with limited moisture return behind the Pacific front.
Another cold front looks to slide across the region Wednesday, but
any rainfall with this feature looks to remain over the northwest
Gulf where better moisture resides. Temperatures during this time
are expected to remain above normal with highs in the upper 60s to
mid 70s and lows in the 50s.

Huffman

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      54  76  56  74  51 /   0  10  20  10  30
Houston (IAH)              58  77  60  75  55 /  10  10  40  30  20
Galveston (GLS)            63  73  64  71  59 /  10  30  50  30  20

&&

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

$$

Discussion...11



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