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fxus64 kbro 281117 aaa 
aarea forecast discussion...updated
National Weather Service Brownsville Texas
617 am CDT Fri Jul 28 2017

Discussion...updated for latest aviation discussion below.


Aviation...VFR conditions to prevail today and tonight as high
pressure continues to build over the region. Light southeast winds
with occasional higher afternoon gusts are anticipated.


Previous discussion... /issued 403 am CDT Fri Jul 28 2017/

Short term (today through saturday): latest model trends remain
on track with the mid and upper level ridge indicated to expand
across Texas the next 24-36 hours and beyond. This will continue
to gradually dry out the atmosphere with pwats lowering to 25
percent of normal Saturday. This should continue to keep the
chance of rain at or near zero percent with only a very isolated
brief shower over the Gulf waters. As the atmosphere drys out and
the ridge axis builds more directly overhead heights and
thicknesses increase and 850mb temperatures inch upward into the
22-24c range which will translate to many locations exceeding 100
degrees both today and Saturday. The only reprieve will be east of
the 69e where mid to upper 90s are expected and the immediate
coast where lower 90s will be the rule. Dewpoints drop pretty
significantly in the west the next two days allowing for humidity
levels to crash into the 20 and 30 percent range. Pressure
gradient remains on the weak side but with the intense heating
deep mixing should result in occasional gusty periods in the
afternoon but should not be sustained sufficiently to preclude any
critical fire weather threats.

Long term (saturday night through thursday): Saturday night into
Sunday remain rain free as dry air remains in place and high
pressure dominates the region. Forecast for the upcoming week is
muddled, as each model focuses on different small-scale features
and the effects they would bring to the valley. Main overarching
midlevel patter is more well-agreed upon, that the US will
transition into a highly amplified pattern, with large ridge
across The Rockies and large trough covering the eastern 2/3rds of
the US. This amplified trough will bring flow from the north
through the week, with embedded impulses sweeping across the
state. Timing on these is the problem, as each model focuses on a
different feature. GFS hints at a weak backdoor front as early as
Monday, while ec package hints at a wind shift/front midweek. If
any of these features would bring a boundary into the region, they
would tap considerable moisture that will be already in place at
lower levels all week. With all this, have kept low rain chances
each day this week except Tuesday, but confidence is still fairly
low until the smaller features become better resolved in models.

today through saturday: broad weak high pressure extending across
the Gulf and subtle lower pressure over NE Mexico to maintain a
light to moderate southeast flow. Favorable marine conditions are
anticipated today and tomorrow with slightly higher winds over the
Laguna during the afternoon hours then across the Gulf waters
overnight. Slight seas are expected with occasionally higher wind
waves developing in the evening and overnight hours.

Saturday night through monday: light onshore flow continues
through the middle of next week as high pressure remains in
control of the northern Gulf. Winds each day may not reach above
10 knots, which will keep seas 2 feet or less throughout the


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