Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 152328

Area Forecast Discussion
National Weather Service BROWNSVILLE TX
628 PM CDT Sat Oct 15 2016

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


.AVIATION...High pressure building over Texas continues to dry
out the atmosphere with a very shallow layer of moisture in place
in the lowest 4000 feet. The drier air aloft will continue to mix
downward eroding the limited moisture through Sunday. This will
maintain VFR conditions with only a low chance and short duration
of MVFR cigs or vsbys mainly over the Northern and Western
Ranchlands. Low confidence and low probabilities of MVFR at KMFE
but a few signals do indicate patchy mvfr cigs around
sunrise enough to warrant a short tempo group. Light Southeast
winds persist tonight and Sunday.


.PREV DISCUSSION... /issued 319 PM CDT Sat Oct 15 2016/

SHORT TERM (Tonight through Sunday Night):  Water-vapor satellite
imagery and upper-air analysis fields show mid-level high building
eastward from northern Mexico into western portions of Texas at this
time.  Attendant subsidence and dry air aloft also evident, with 12Z
BRO sounding measuring precipitable water at 1.29". Surface high
pressure over the NW Gulf of Mexico coupled with troughing from the
Central Plains back through the interior of Mexico are driving
breezy SE winds this afternoon.

Hot, humid, and essentially rain-free conditions will continue
through the short-term, as the mid-level high center continues to
migrate eastward across TX.  Patchy fog is possible in the hours
around dawn from the northern Ranchlands down to the Harlingen
vicinity as temps cool down to the dewpoint.  Subsidence aloft and
moisture confined below 850mb will keep rain out of the forecast for
all land areas, however. 1000-500mb thicknesses nudge upward from
today to Sunday, adding another degree or two to afternoon max
temps. Near-record high temperatures for the date are forecast for
Brownsville, Harlingen, and McAllen as temperatures rise into the
mid-upper 90`s.

LONG TERM (Monday through Saturday): 500 mb ridging will persist
over Deep South TX from Monday through Wednesday which will
maintain above normal temps and nil pops for the first half of
next week. A serious trough axis will move southeast out of the
Pacific Northwest and will push into the central portion of the
lower 48 states late Wednesday and Thursday. As this trough axis
pushes further east and closes off over the southeastern states
and near the Gulf Coast Friday night into Saturday a pretty decent
cold front will move through the RGV on Thursday. A cooler airmass
will move into the region for the latter half of next week which
will drop the temps down closer to climo for south Texas for late
October. As the 500 mb trough/closed low moves east next weekend
500 mb ridging will start to build back in place pretty quickly
allow for the temps to start warming back up after next weekend.

Moisture advection ahead of the fropa is decent but short lived
and looks to be limited mainly to the Thursday Night through
Friday morning time period. So will maintain fairly low end pops
around the fropa Thursday and Friday.

The ECMWF and the GFS are in much better agreement in the
synoptic pattern through Days 3 through 7 and in the timing and
strength of the central Plains trough digging towards the RGV next
week. The GFS and ECMWF temp and pop guidance are accordingly in
much better agreement today versus yesterdays runs. Run to run
consistency with the GFS MEX MOS runs have been decent. So will be
going with a general model blend for the longer range. Overall
forecast confidence has improved today versus yesterday due to the
better model performance and is above average through Day 7.

MARINE (Now through Sunday night):  Light to moderate SSE winds and
seas around 3 ft. have been observed at Buoy 42020 this afternoon.
These winds will become more moderate at night but remain below
Exercise Caution criterion.  A 7-8 second period swell from the E
continues to roll in across the Gulf, which will keep combined seas
in the 3-4 ft. range. A modest moisture increase over the outer
Gulf waters late Sunday night may result in a very slight chance
of showers.

Monday through Thursday night: Persistent surface ridging over the
Gulf of Mexico will maintain a light to moderate southeast flow
from Monday on through Wednesday. The fropa next week will then
allow a stronger northeast flow late Thursday and Thursday night
likely resulting in the winds and seas increasing up close to SCA
levels late in the marine forecast period.


BAYVIEW/PORT ISABEL  74  89  76  91 /   0   0   0   0
BROWNSVILLE          72  94  72  93 /   0   0  10   0
HARLINGEN            70  96  70  95 /   0   0   0   0
MCALLEN              73  98  71  97 /   0   0   0   0
RIO GRANDE CITY      71  95  71  98 /   0   0   0   0
SOUTH PADRE ISLAND   80  84  78  86 /  10   0   0   0




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