Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 170548 AAB

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1248 AM CDT Sat Jun 17 2017

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


.AVIATION...Mostly clear skies with southeast winds around 10
knots prevail across Deep South Texas early this morning. A few
low clouds will drift across the area overnight and enough clouds
may briefly lower ceilings to 1800 feet. Due to low confidence and
a fairly dry atmosphere, will not mention a MVFR tempo group at
this time. Otherwise, VFR conditions expected to continue for the
next 24 hours with high pressure in place. Breezy conditions will
develop later this morning with gusts around 25 knots in the
afternoon. Southeast winds will gradually decrease to around 15
knots by late Saturday evening.


.PREV DISCUSSION... /issued 649 PM CDT Fri Jun 16 2017/

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...Lack of moisture continues to inhibit nearly all cloud
formation across the valley. Only clouds are streaming in from
offshore, but are not able to hold together much after landfall.
This trend will continue tonight into tomorrow, as dry air remains
in place. Enough clouds may drift into KBRO at the same time this
evening to briefly lower cigs to 2500, but this is a very limited
time event, and is still fairly unlikely. Winds will decrease
somewhat tonight, but will likely remain around 10 knots, with
gusts continuing around 15 knots. Winds will increase again
tomorrow, reaching near 20 knots with higher gusts during the
afternoon. Temperatures will again approach 100 degrees for KBRO
and KHRL and may again approach 105 at KMFE.

PREV DISCUSSION... /issued 315 PM CDT Fri Jun 16 2017/

SHORT TERM (Tonight through Saturday Night): A 500 hPa ridge anchored
over North Central and Northwest Mexico will support short term
subsidence and stability, as well as hot weather, over deep South
Texas and the RGV. Almost without saying, above normal temperatures
will prevail. High temperatures Saturday will inch higher, ranging
from the lower 90s near the coast to triple digits across portions
of the Mid and Upper Valley. Heat index values will be in the 105 to
110 degree range for a few hours over most inland areas. Surface low
pressure across West Texas interacting with high pressure across the
Gulf of Mexico will support moderate to breezy southeast winds on
Saturday. Overnight low temperatures will range from 75 to 80 under
mostly clear to partly cloudy skies. Relative humidity values across
the Upper Valley will range from 25 to 35 percent Saturday afternoon
with 20 ft winds of 10 to 15 mph and drying fuels. Thus, continued
monitoring of fire weather parameters should be sufficient for now,
with no supplemental fire weather products needed.

LONG TERM (Sunday through Friday): 500mb subtropical ridge will
remain entrenched across the southwest United States and northern
Mexico the rest of the weekend into early next week. The main
feature of concern is the area of disturbed weather across the
western Caribbean Sea and where and if it will develop into a
tropical low. The global models continue to diverge with the GFS
continuing to bring the surface low off the Yucatan Peninsula
Sunday into the eastern Gulf of Mexico Monday as a hybrid
tropical system (surface trough/shear axis) and the ECMWF
bringing the surface low westward across the southwest Gulf of
Mexico Monday into Tuesday. The strength of the upper level ridge
across the southwest U.S. will have a major role in determining
the future track of the tropical feature assuming it develops into
a tropical depression or tropical storm next week. Hot and dry
conditions will prevail the rest of the weekend through at least
the middle of next week before any influences from the tropics
provide enough moisture for rain chances...mainly across the
coastal waters and the lower Texas coast through the rest of the
forecast period.

MARINE (Now through Saturday night): Moderate southeast winds and
low to moderate seas will prevail. Diurnal trends, driven in part by
low pressure over North and West Tex Saturday interacting with high
pressure over the Gulf, will support SCEC conditions on the Laguna
Madre by day and on the Gulf waters by night.

Sunday through Wednesday...Moderate to strong southeast winds will
prevail across the coastal waters Sunday with surface low pressure
across west Texas and high pressure across the northern Gulf of
Mexico. Light easterly winds should prevail across the lower
Texas coast Monday before an area of disturbed weather across the
Yucatan Peninsula moves into the southern Gulf of Mexico. The
rest of the marine forecast will be highly dependent on the future
development and track of the area of disturbed weather. Will go
ahead and increase winds and seas higher slightly offshore the
lower Texas coast Tuesday into Wednesday even though there is a
considerable amount of uncertainty with the development of a
tropical system over the Gulf of Mexico next week.




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