Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 162141

Area Forecast Discussion
National Weather Service BROWNSVILLE TX
341 PM CST Mon Jan 16 2017

.SHORT TERM (Tonight through Tuesday Night): Latest surface analysis
indicates a weak cold front draped across the central portions of
the forecast area. Gusty southerly winds prevail near the coast with
light west to northwest winds across the western portions of Deep
South Texas this afternoon. The frontal boundary will continue to
linger across the area this afternoon before drifting back to the
west later tonight. Isolated to scattered showers are forecast for
all of Deep South Texas and the Rio Grande Valley Tuesday and
Tuesday night as another weak cold front approaches the area.
Temperatures will remain above normal through the entire short term
forecast period. Patchy fog will also be possible later tonight and
late Tuesday night.

.LONG TERM (Wednesday through Monday): A 500 mb closed low/trough
axis will move across northern Mexico and the south central Plains
states on Wed and Thurs. Pretty good deeper layer moisture and
instability appears to pool ahead of this trough and associated
cold front. So will maintain the threat of conv for both days as
both the GFS and ECMWF keep the best conv pops in place during
this period. As the trough axis lifts out to the east and
northeast late Thurs and Fri much drier and more stable air will
move into the region decreasing the pops pretty quickly. The drier
and more zonal 500 mb flow in addition to the increasing daytime
heating will allow the temps to warm steadily for Fri and Sat with
nil pops prevailing. However another fast moving 500 mb trough
will move out of the Desert Southwest this weekend. This will
allow another stronger but drier cold front to move through the
RGV late Sat/early Sunday. The more Pacific airmass moving in
behind this weekend front will cool down the temps closer to climo
for late January on Sun and Mon.

The GFS and ECMWF 500 mb fields are in good agreement in the
handling of the synoptic features through Day 7. Run to run GFS
MEX MOS temps and pops are pretty stable over the last several
days runs. However...fairly significant differences persist
between these two longer range models for the run to run
temps/pops with the ECMWF maintaining warmer and slightly wetter
solutions for the longer range versus the GFS. Considering the
persistent warm temps that the RGV has witnessed throughout this
winter...will lean a little more in favor of the ECMWF solution.

SPC maintains a marginal risk for svr conv mainly near the Coastal
Bend area for early Wed as the 500 mb trough axis moves closer to
the region interacting with decent instability values. Despite the
strength of the 500 mb trough axis moving through the area...the
threat for svr wx will likely be limited due to the marginal
instability. For now will not mention any severe weather in the
current forecast wording.

Overall forecast confidence in the longer range wording is above
average today.


.MARINE: (Now through Tuesday Night): Buoy 42020 reported south
southeast winds around 12 knots gusting to around 14 knots with seas
of 6.6 feet with a period of 8 seconds at 14 CST/20 UTC. Moderate
winds and seas are expected to continue through the rest of the
forecast period due to persistent swells and frontal boundary across
portions of Deep South Texas and the Rio Grande Valley. Small Craft
Exercise Caution likely for portions of Lower Texas Gulf waters
through Tuesday night.

Wednesday through Saturday Night...A pretty weak PGF will prevail
over the lower TX coastline through the latter half of this week
which will keep fairly low winds and seas in place. Northwest
winds moving in behind a weekend cold front moving through the
region will allow the winds and seas to build back up near SCA
levels starting late Saturday.


BAYVIEW/PORT ISABEL  68  81  66  72 /   0  20  30  30
BROWNSVILLE          69  83  66  74 /   0  20  30  30
HARLINGEN            68  83  65  75 /   0  20  40  30
MCALLEN              69  86  65  77 /   0  20  40  30
RIO GRANDE CITY      67  85  62  74 /   0  20  50  30
SOUTH PADRE ISLAND   68  79  66  68 /  10  20  30  30




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