Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 230924

Area Forecast Discussion
National Weather Service Brownsville TX
324 AM CST Thu Nov 23 2017

...A Tranquil Thanksgiving Day Ahead...

.SHORT TERM (Today through Friday): 500mb high centered just off
the Baja CA coast and a broad mid level trough over the Eastern
Gulf of Mexico will maintain a dry northerly flow over South Texas
today and Friday. At the surface, high pressure will be centered
over Deep South Texas today and tonight spreading along the Texas
coast Friday. Atmosphere continues to dry out with layer mean RH
in the 15- 25 percent range up to 400mb the next two day. No
appreciable weather is expected with this dry atmosphere in place
with no clouds to mention, light winds and just a large diurnal
range in temperatures.

.LONG TERM (Friday Night through Wednesday): The long term begins
with a departing high pressure system exiting stage east. This
will allow surface winds to shift to more of a return
(southeasterly) flow. A weak cold front will be on the move across
northern/central Texas. There is a bit uncertainty whether or not
this feature will clear the RGV, but adjusted temperatures down
slightly on Sunday. With a strong northwest flow aloft on the
eastern side of the upper high, can`t rule out the front (or what
is left) moving through.

Any subtle decrease in temperatures Sunday rebound back into the
above average category on Monday/early next week as 1)return flow
sets up across the region as the high behind the weak front jets
eastward across the Ohio Valley and 2) the ridge aloft begins to
build over the region. That said, the influence of this ridge will
be brief as globals significantly weaken this feature as it
progresses eastward.

Globals are both pinging another cold front pushing into Texas
sometime around midweek next week. There are some rather large
differences between both the GFS and ECMWF at this time. GFS is
more progressive and keeps the parent trough an open wave,
however, the ECMWF closes off an upper low across the Four-Corners
region. Given the trends over the last several weeks, the GFS is
favored in terms of temps and fropa timing/strength at the moment.
Regardless, with a likely frontal passage, did keep temps on the
low side and kept some mention of POPs toward the end of this



.MARINE: (Today through Friday) Surface high pressure has become
centered west of the Lower Texas Coast allowing for the pressure
gradient to weaken. Nearby buoys and platforms show winds dropping
below Small craft advisory levels and with winds and seas continuing
to lower this morning the SCA will be cancelled early. Excellent
marine conditions are expected as early as this afternoon and should
continue tonight and Friday.

(Friday Night through Wednesday) Simply put, seas and winds should
start out very light for this timeframe. A very weak frontal
boundary will near the area during the day Sunday, however, seas
and winds do not bullishly respond given the lack of meaningful
pressure gradient. A stronger cold front will near the region by
midweek next week, which should increase winds and seas to at
least SCEC if not SCA thresholds.


BAYVIEW/PORT ISABEL  69  46  75  61 /   0   0   0   0
BROWNSVILLE          73  48  77  59 /   0   0   0   0
HARLINGEN            73  45  78  57 /   0   0   0   0
MCALLEN              75  48  79  56 /   0   0   0   0
RIO GRANDE CITY      75  44  80  54 /   0   0   0   0
SOUTH PADRE ISLAND   68  57  73  66 /   0   0   0   0




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