Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 171034

Area Forecast Discussion
National Weather Service Brownsville TX
434 AM CST Fri Nov 17 2017

.SHORT TERM (Now through Saturday): Some patchy fog and low clouds
have developed mainly across portions of the northern ranchlands
this morning. The fog and low clouds should quickly lift and burn
off with diurnal heating later this morning. Otherwise, well above
normal temperatures are expected through the short term. High
temperatures today and Saturday will be in the mid to upper 80s
under a mix of sun and clouds. Record high temperatures are possible
across the area today. Low temperatures tonight will range from the
the upper 60s inland to the mid 70s along the coast. Generally rain-
free conditions will prevail across deep south Texas through
Saturday. A cold front will approach the northern ranchlands towards
the late afternoon hours on Saturday.

.LONG TERM (Saturday Night through Thursday): A deep 500mb
trough and surface low over the northeast U.S. will push a strong
cold front through Deep South Texas Saturday night into Sunday.
The main impacts behind the front will be strong north winds along
the coastal counties and over the Gulf waters with much cooler
temperatures on Sunday. We will see a sharp temperature drop from
near record high temperatures in the lower 90s on Saturday to lows
in the mid 50s Sunday morning. Kept isolated PoPs in for Sunday
due to moisture lacking above 850mb and a fairly progressive
frontal passage. Morning lows on Monday will be a few degrees
cooler in the upper 40s across the ranchlands to mid 50s along
the river as northerly winds slowly shift to the east and
eventually southeast late in the day.

Surface high pressure will shift off to the eastern U.S.,
returning our southeast flow briefly, which should allow
temperatures to rebound into the lower 80s Tuesday afternoon. By
mid-week, models continue to differ with our next main storm
system. This 00Z model run brings the two main global models
a little closer to agreement than past runs, with both bringing a
deep mid-level trough somewhere from South Texas to the northern
Gulf and another potentially significant cold front through the
CWA. The main question will be how much moisture we will see and
where the best upper level support will be for precipitation. The
GFS brings a 500mb trough/closed low over Deep South Texas with
coastal surface troughing, which would favor more rain for our
area. The ECMWF keeps the trough well to our east over the
northern Gulf, which would bring much drier air and little
rainfall. Decided to keep isolated showers in for the eastern half
of the area and over the coastal waters for now due to modest
confidence on moisture return prior to the frontal passage.

Temperatures the rest of the week will be near normal to a few
degrees below normal with highs in the upper 70s and cooler
morning lows in the 50s through Thanksgiving.


.MARINE (Now through Saturday): Buoy 42045 (TGLO TABS Buoy K)
reported south-southwest winds around 14 knots gusting to around 16
knots at 02 CST/0800 UTC. Light to moderate south-southeast winds
and moderate seas are expected along the lower Texas coast today.
Developing low pressure across north Texas tonight will support a
tight pressure gradient. Small craft should exercise caution tonight
into Saturday morning on the Gulf waters due to the increasing winds
and building seas.

Saturday night through Wednesday: Marine conditions will
deteriorate rapidly Saturday night into Sunday as a strong cold
front passes through the lower Texas coastal waters. Strong north
winds of 25 to 30 knots can be expected with occasional gusts to
gale force. Confidence for frequent 34-kt gusts was too low to
issue a Gale Watch at this time, but Small Craft Advisories will
be nearly certain. As high pressure shifts to the eastern U.S.,
southeast winds will return and conditions will improve early in
the week. Another cold front may move through by the middle of the
week, which would bring another round of stronger north winds and
higher seas.


BAYVIEW/PORT ISABEL  85  72  87  60 /   0   0  10  20
BROWNSVILLE          88  73  88  59 /   0   0  10  20
HARLINGEN            90  70  89  56 /   0   0  10  20
MCALLEN              91  71  90  56 /   0   0   0  20
RIO GRANDE CITY      92  68  91  55 /   0   0   0  10
SOUTH PADRE ISLAND   82  75  83  64 /   0   0  10  20




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