Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 220912

Area Forecast Discussion
National Weather Service BROWNSVILLE TX
412 AM CDT Sat Oct 22 2016

.SHORT TERM (Today through Sunday): Not much to complain about
this morning with the coolest temperatures since early May.
Through the short term the main players will be a mid level 500mb
ridge overhead, surface ridge tracking east and a weak upper level
trough over NW Mexico. Main challenge will be how much cloud cover
will we see and how this cloud cover will impact temperatures
tonight and Sunday. At this time, a well mixed stratocu field is
seen just east of SPI some of these clouds may move into the SPI
vicinity prior to sunrise but should dissipate as the cooler
airmass over the Gulf moderates after sunrise. For the rest of the
CWA a mostly sunny day with some high clouds beginning to stream
in from the southwest in response to an upper trough over Baja CA.
These thinner clouds should not impact temperatures today with
plenty of insolation to modify the cool air allowing for at least
20 to 25 degrees of warming today. This should put everyone back
into the 80s this afternoon with very comfortable humidity levels
along with a light northeast to east wind.

Temperature challenge begins tonight as mid level and surface
ridge move east and the upper trough moves into Texas by Sunday.
Surface winds return off the Gulf beginning the increase of low
level Gulf moisture while the upper trough allows for a Pacific
moisture to spread over the region. First, some patchy fog may
form by Sunday morning as winds will remain relatively light. Do
not expect widespread low visibilities with enough wind to keep
the patchy fog above dense levels. Overnight lows to warm up as
much as 10 degrees as the dewpoints climb in response to the winds
turning southeast, so will not be as comfortable Sunday morning
but still in the low to upper 60s and possibly higher if high
clouds increase faster then expected. Next, Models suggest a
thickening and lowering of high level cloudiness with low level
clouds forming rapidly Sunday as the upper trough moves into West
Texas. This would suggest a mostly cloudy to cloudy afternoon
which will likely impact high temperatures. With medium confidence
in the thicker cloud cover overspreading the CWA earlier have
lowered Sunday`s highs by a few degrees and at least one or two
categories below guidance. No Rain is expected but can not rule
out some sprinkles falling out of the thickening high clouds.

LONG TERM (Sunday night through Friday): H5 ridging will amplify
over the Western United States early in the long term, with high
pressure over the Gulf States. This will set up a seasonal weather
pattern with generally southeast winds and returning moisture, and a
weak trend of warming temperatures. A weak short wave trough will
move from west to east through North Texas and the base of the
ridge Sunday into Monday, which when combined with convective
activity from the Southwest Gulf will mean mildly unsettled
weather locally.

Will see a good moisture pull from the Gulf on Monday, with isolated
to scattered showers and thunderstorms. Precipitable water will
increase significantly, from under an inch to an inch and a half
Stuck with the game plan of the inherited forecast with regard to
pops, whose numbers looked reasonable. Weak low pressure will
sustain itself over the Southwest Gulf the first half of the week,
and overnight convection there will become convection reaching the
lower Texas Coast during the day Monday through Wednesday. Partly
cloudy skies may become mostly cloudy at times, with high temps in
the upper 80s to near 90.

The transiting trough will amplify over the plains by mid week and
after, with ridging to the west also shifting east. This will weaken
high pressure over the Gulf and cause winds to veer more to east. A
longer period swell may develop, and some beach runup may occur
later in the week. As the trough matures into a storm system over
Illinois Wednesday into Thursday, ridging will continue to dominate
farther west, and Canadian air will get pulled south by Thursday
with winds shifting to northeast and with drier air aloft moving
overhead from the north. Temps will remain above normal with lesser
rain chances after mid week. Thus for Wednesday night through
Friday, the northern Mexico ridge will build east to include all of
the western half of Texas including the Valley, and drier air will
follow. Increasing sunshine and lower humidity will kill off rain
chances, but will also allows morning lows to dip slightly by the
end of the period.


Today through Sunday...Winds have dropped below 10 knots and sea
are steadily falling and should be below 6 feet by sunrise. As
surface high pressure moves across the NW Gulf today and continues
to track east Sunday the coastal waters will continue to trend
towards more favorable conditions. winds to turn east to southeast
today with a light to moderate southeast flow on Sunday. Seas to
lower to 3 to 4 feet by later today and remains within this range
for the remainder of the weekend.

Sunday night through Wednesday...Mid level ridging over the
Western United States and high pressure over the Gulf Coast
States will result in light to moderate east southeast winds and
low to moderate seas Sunday night and through the long term
period. Weak low press over the Southwest Gulf will keep weather
conditions unsettled and will encourage shower and thunderstorm
activity Monday, Tuesday, and Wednesday afternoons, which will
move north along the Northeast Mexican Coast, and then over land
reaching as far east as the mid valley. Winds will shift to
northeast Wednesday night as mid level ridging builds over the
high plains and high pressure over the plains interacts with lower
pressure south of the local marine area.


BAYVIEW/PORT ISABEL  83  70  83  75 /   0   0  10  10
BROWNSVILLE          85  68  84  74 /   0   0  10  20
HARLINGEN            85  65  85  71 /   0   0  10  20
MCALLEN              86  66  86  72 /   0   0  10  20
RIO GRANDE CITY      86  64  86  71 /   0   0  10  10
SOUTH PADRE ISLAND   80  74  82  77 /   0   0  10  10




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