Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 200546 AAC
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service BROWNSVILLE TX
1246 AM CDT TUE SEP 20 2016

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

&&

.AVIATION...Mostly clear skies with light and variable winds
prevail across deep south Texas early this morning. High
pressure and dry air aloft will maintain VFR conditions for the
next 24 hours. Surface high pressure over the Northern Gulf will
allow for light and variable winds to continue overnight..with
gusty NE to E winds this afternoon. Winds are expected to become
light and variable again later this evening.

&&

.PREV DISCUSSION... /issued 1010 PM CDT MON SEP 19 2016/

DISCUSSION...Just a quick update to tweak overnight lows and
Tuesday afternoon highs. Current thinking is that the strong ridge
of high pressure aloft will remain stagnant over the region and
temperatures will remain elevated. With plenty of dry air
aloft...moisture levels are low. Never-the-less...heat index
values will continue to be in the 105 to 110 degree range. Some
locations could be a degree or two higher...however that will
remain an isolated occurrence. Otherwise...overall forecast on
track.

PREV DISCUSSION... /issued 642 PM CDT MON SEP 19 2016/

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...High pressure aloft will keep hot and dry weather in
place...with VFR conditions expected through the period. Surface
high pressure over the Northern Gulf will allow for light and
variable winds overnight...with gusty NE to E winds during the day
on Tuesday.

PREV DISCUSSION... /issued 249 PM CDT MON SEP 19 2016/

SHORT TERM (Today through Tuesday):
A broad 500mb ridge centered over the Texas Big Bend and
extending overhead will remain nearly in place through the
forecast period. This will result in above average temperatures
and generally rain-free conditions through Tuesday night.
Reinforcing sfc high pressure will move over the Northwest Gulf
later today, causing light east southeast winds to back to the
east or northeast by tonight. Low temps tonight will be in the mid
to upper 70s with the possibility of a few hours of patchy light
ground fog for the brush country and ranchlands early Tuesday
morning. Hot weather will prevail again on Tuesday, under mostly
sunny skies and light winds, with afternoon heat index values in
the 105 to 110 degree range. High temperatures will range from the
mid and upper 90s to above the century mark west of I-69E, and
could near a record value in McAllen, where the current record for
Tuesday is 100 degrees. Temperatures will cool under mostly clear
skies Tuesday night, with low temperatures again in the mid to
upper 70s.

LONG TERM (Tuesday Night through Sunday):
Area remains between H5 ridge to the north and west and the weak
cutoff low trying to remain viable across the northern Gulf. The
trough merges with a passing inverted trough moving across the
souther Gulf, and sweeps west into northern Mexico. Models
continue to have instability in the region starting Wednesday, but
have backed off considerably on the arrival of deeper moisture
until Friday, so rain chances are held back for most of the rest
of the week. Increased moisture starting Friday will bring a
better chance for showers, with the current best chances showing
up on Sunday. Since showers are holding back for most of the
remainder of the week, have upped temperatures to come closer to
persistence, as there`s nothing entering the region to
significantly lower temperatures each day.

MARINE:
Tonight through Tuesday night...Surface high pressure will remain in
control through the short term, resulting in light to moderate winds
and low to moderate seas.

&&

.BRO Watches/Warnings/Advisories...
TX...None.
GM...None.
&&

$$

This product is also available on the web at:
HTTP://WEATHER.GOV/RGV

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