Saturday, January 16, 2021

Jan. 16 21

 Area Forecast Discussion

Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 162326
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
526 PM CST Sat Jan 16 2021

.AVIATION...
VFR with light winds this evening and overnight. TAF sites will see
increasing mid/high clouds tomorrow in association with a weak shortwave
trough and accompanying weak cold front. Winds will generally W to NW
under 10 knots. VFR tomorrow night and on into early Monday morning
with light winds.  42

&&

.PREV DISCUSSION... /ISSUED 325 PM CST Sat Jan 16 2021/

SHORT TERM [Through Monday]...
Northwesterly winds continue to decrease as an area of high pressure
moves in closer to the area. Still seeing a few bouts of wind gusts
around 15 knots due to the steep low-level lapse rates and a
unidirectional wind flow into the mid-levels. With winds slowing
down going into the evening, dew points remaining low, and clear
skies prevailing, another cold night is expected for tonight with
temperatures dipping down into the mid-to-upper 30s. Dew points will
remain on the low side with 20s persisting through Sunday morning.
Temperatures will be on the rise going into early next week as CAA
comes to an end on Sunday morning. Highs will be in the mid-to-upper
60s on Sunday and the upper 60s/low 70s on Monday. Low temperatures
for Sunday night will be a bit warmer due to onshore flow returning
as the high pressure begins to move off to the east. Expecting
temperatures to be in the low-to-mid 40s for most with upper 30s for
our far northern counties.

Forecast models are in agreement that a weak shortwave trough will
swing through the CWA on early Sunday morning along with a weak cold
front, but this will not cause any adverse weather or offer any
noteworthy cold air. This is because the trough is positively
tilted, instability is very low, PWATs are less than 0.5", plentiful
dry air remains in the low-levels, and there will be quite a bit of
upper-level convergence. At best we`ll see some mid-to-upper level
clouds as it moves through, but only last through late Sunday
morning before clear skies return. The area of high pressure moves
off to the east on late Sunday night/early Monday morning. This will
put us into an onshore southeasterly flow, which is important for
the rest of the week as this will steadily increase our moisture and
instability.  26

LONG TERM [Monday Night Through Saturday]...
A shallow cold front is fcst to move into portions of n/ncntl Tx
Monday & Tuesday and become a focus for precipitation as llvl
moisture levels increase from prevailing onshore winds off the
Gulf. Anticipate that the boundary will stall before reaching
southeast Texas with upper trof still being situated well to the
west over SoCal & Baja. Disturbances embedded in the swly flow
aloft along with the proximity of the stalled front may trigger
sct precip at times across the NW 1/2 of the CWA Tues-Thurs.
Further south closer to the coast, we`ll be on the lookout for
periods of sea fog. The upper trof to the west will fill as it
ejects newd across the Plains later in the week. The next front
penciled in for Thursday night into Friday afternoon, will
probably have a better southward push. Sct precip along this
boundary will come to an end as it pushes offshore later in the
day. 47

MARINE...
Although the wind speeds have decreased, the wind directions remains
northwesterly which means the seas will continue to decrease going
into Monday. The persistent offshore flow will allow for at least
one more day of abnormally low tides for the bays. As a result, a
Low Water Advisory is in effect for both Matagorda Bay and Galveston
Bay through this evening. Winds will become light tonight as high
pressure moves overhead. A weak cold front will briefly change winds
to northwesterly on Sunday morning. High pressure moves off to the
east on Sunday night/Monday morning, which will introduce an onshore
southeasterly flow. Wind speeds will approach SCA criteria on Monday
night/early Tuesday morning. The onshore flow will persist through
most of the week and seas will build up to 4-7 feet by Tuesday. A
warmer airmass will be moving over the cool nearshore waters, so
sea fog will be a possibility Wednesday through Friday morning. 26

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      36  65  38  68  56 /   0   0   0   0  20
Houston (IAH)              37  65  41  67  53 /   0   0   0   0  20
Galveston (GLS)            47  61  53  63  58 /   0   0   0   0  10

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...Low Water Advisory until 8 PM CST this evening for the following
     zones: Galveston Bay...Matagorda Bay.

&&

$$

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