Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 152338

Area Forecast Discussion
National Weather Service Brownsville TX
538 PM CST Wed Feb 15 2017

.DISCUSSION...Updated for latest aviation discussion below.


.AVIATION...High pressure will settle in across Texas this evening
with winds becoming light north to northeast. As the high shifts
east on Thursday...southeast winds will return. VFR conditions
will prevail.


.PREV DISCUSSION... /issued 235 PM CST Wed Feb 15 2017/

SHORT TERM (Tonight through Thursday Night): 500mb low/trough
across northwest Mexico/eastern Pacific tonight will move eastward
across northern Mexico and west Texas tomorrow into tomorrow night.
At the surface...high pressure across central TX tonight will move
eastward Thursday allowing an onshore flow to return. Low to mid
level moisture will increase across northeast Mexico into the CWA
Thurs night and this will provide a slight chance to chance of
showers...elevated...across the area. Clear skies and light winds
tonight will allow radiational cooling with lows in the 40s by Thurs
morning. Temperatures will return to normal Thurs afternoon through
Thurs night with the onshore flow returning.

LONG TERM (Friday through Wednesday): The period begins with a
closed upper low migrating eastward through north TX with the base
of the low set to pass over deep south TX around midday Friday.
Weak lift ahead of the trough will combine with low level moisture
for chances of showers area-wide early in the day and these
showers will pull toward the coast through the day as the trough
moves east. Showers should end by no later than the afternoon
hours as a dry northwest flow develops, both surface and aloft,
behind the departing trough. High temperatures on Friday should
generally be in the mid 70s along the coast with lower 80s inland.
Very strong high pressure in the form of a shortwave ridge then
builds over the forecast area Friday night and Saturday ahead of a
large and vigorous low pressure system approaching from the west.
Saturday will be hot due to the strong high pressure with high
temperatures reaching much above normal values and will range from
the mid 80s at the coast with lower 90s inland.

For Sunday, strong southerly flow will develop aloft over the Rio
Grande Valley as the shortwave ridge pushes east in response to
the approaching large low pressure system that looks to be
located over northwest Mexico by this time. High temperatures on
Sunday will once again be above normal but won`t be as hot as
readings that will be reached on Saturday. Mostly due to
increasing cloudiness, highs on Sunday will reach into the lower
80s at the coast to upper 80s inland. Chances of showers and
thunderstorms will begin to overspread the forecast area Sunday
afternoon as a strong surface cold front approaches from the
northwest and combines with abundant low level moisture that will
be in place. Sunday night/early Monday morning may be interesting
as some of the medium range models are indicating that a squall
line of weak to moderate intensity may form along the cold front
as it moves southeast through the region and interacts with dew
points that will be in the mid 60s to lower 70s and CAPEs that may
reach 3000 j/kg. Additionally, storms that form along the front
will receive some upper support as a somewhat diffluent pattern
will be in place across central TX. All of these factors point to
a widespread rain event developing Sunday night with a number of
locations receiving heavy rain at times, with possibly some hail
and damaging winds.

Low chances of showers and thunderstorms will continue through
the day on Monday, and even on into Tuesday, as the large low
pressure system moves eastward directly overhead of deep south TX.
Highs both days should generally be in the mid 70s at the coast
with lower 80s inland. If the timing of the movement of the upper
low persists as depicted in the medium range models, a drier
northwest flow should develop over the forecast area once again,
both surface and aloft, Tuesday afternoon through next Wednesday
as high pressure builds in from the west bringing pleasant, near
normal temperatures.

MARINE (Tonight through Thursday night): Seas were near 7 feet
with north winds near 21 knots at buoy020 early this afternoon.
Winds and seas will continue to diminish this afternoon into this
evening as surface high pressure settles across the lower Texas
coast tonight. Will need to replace SCA with SCEC for the far
offshore waters this afternoon mainly for seas. Light to moderate
north winds will prevail across the coastal waters tonight as a
result. The surface ridge across the TX coast will move eastward
Thursday allowing winds to veer to the east. Light east winds
Thursday will veer to the southeast Thurs night as the surface
ridge moves over the northeast Gulf coast.

Friday through Monday: Modest southeast to south flow with seas
of 2 feet to prevail Fri/Sat as the surface pressure gradient
remains rather slack. Southerly winds will begin to build Sunday
ahead of a strong cold front approaching from the northwest. This
front will move across the waters late Sunday night through Monday
morning with seas reaching 5 to 7 feet. Small Craft Advisories
will most likely be needed during the Sunday afternoon through
Monday period.




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