Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 262152
AFDBRO

Area Forecast Discussion
National Weather Service Brownsville TX
452 PM CDT Fri May 26 2017

.DISCUSSION...Erosion of cloud cover allowed heat indices to spike
up to 110-115F across the mid-Lower Valley over the past hour or
two, necessitating the issuance of a Heat Advisory through 7pm.
Updated temp, dewpoint, RH, and apparent temp grids to ensure
consistency between current conditions and ZFP/point-and-click
pages.

&&

.DISCUSSION...Updated for latest marine discussion below.

&&

.MARINE...Obs at NDBC Buoy 42020 and TABS buoys in the outer Gulf
waters have trended below SCA criteria (for both seas and winds)
for a couple of hours, so cancelled the Small Craft Advisory early
there. Will let it ride on the Laguna through scheduled expiration
at 7pm with 20-22 knot readings still fairly widespead.

&&

.PREV DISCUSSION... /issued 316 PM CDT Fri May 26 2017/

SHORT TERM (Now through Saturday night ):Mid level ridging will
build to between 590 and 594 dam in the short term, supporting a
further upward trend in heat. Heat will increase under the mid
level ridge Saturday afternoon. High temperatures will range from
the mid 90s near the coast to near or slightly above the century
mark inland, and will combine with dew points in the 60s and 70s
to produce heat index or feels like temperatures between 107 and
112 for a few hours across the area Saturday afternoon. These
values will in some cases be close to heat advisory criteria, but
will leave the finer details regarding geographic coverage and
duration to subsequent shifts. Otherwise, the short term forecast
is dry and will feature increased low level cloudiness overnight
with moderate to breezy southeast to south winds on Saturday.
Overnight low temps will be in the mid to upper 70s, or even near
80 degrees.

LONG TERM (Sunday through Friday):Models are in overall good
agreement with the slow evolution of the mid/upper level pattern
for next week which will feature an upper level low pressure
trough over the Desert SW extending into the Rockies and farther
NE. Several disturbances will be rotating around this trough
interacting with abundant and deepening moisture from the Gulf of
Mexico giving the region an extended chance of rain for much of
next week.

In advance of the upper trough a cold front at the surface,
extending from a cold upper trough over the Great Lakes, is
expected to move into South Texas Sunday and Monday with a
shortwave trough moving across Northern Mexico into Southwest
Texas. Latest model runs are eyeing on Sunday night and Monday for
substantial thunderstorm development...affect the NW zones Sunday
night and the entire CWA Monday. The front will likely stall
north of over the CWA Tuesday with still enough energy to keep the
chance of rain active. The Front dissipates Wednesday but with the
aforementioned upper trough taking up shop to our west and plenty
of moisture in the atmospheric column the chance of rain is
expected to continue. Differences among the global models will be
factor on how widespread the rain may or may not be. ECMWF is the
farther east with the trough which will be more favorable for
South Texas while the GFS trends with a bit more of a closed low
remaining farther west. A general blend does keep a low end chance
of daytime showers/tstms with plenty of time to see which models
plays out. Temperatures will trend down near to slightly below
average as the chance of rain increases with a slight increase
back to near normal later next week.

MARINE:(Now through Saturday night): Mid level ridging will be in
place overhead with high pressure in control at the surface over the
Gulf. Moderate southeast to south winds will prevail with moderate
seas. Small craft exercise caution conditions will be possible off-
shore with wave heights in the 4 to 6 feet range.

Sunday through Wednesday...A general southeast flow between High
pressure extending over the Gulf and persistent low pressure
across the NE Mexico and West Texas will maintain moderate winds
and seas. Exercise caution conditions will be predominate. Showers
and thunderstorm chances increase Monday and Tuesday with a
continued chance into Wednesday.

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...Heat Advisory until 7 PM CDT this evening for TXZ252>255.

GM...Small Craft Advisory for winds until 7 PM CDT this evening for
     GMZ130-132-135.

&&

$$

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HTTP://WEATHER.GOV/RGV

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