Area Forecast Discussion
Issued by NWS Brownsville, TX
FXUS64 KBRO 271759 AAB
Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1159 AM CST Mon Feb 27 2017
.DISCUSSION...Updated for latest aviation discussion below.
.AVIATION...Daytime CU field remaining thick this morning,
remaining trapped under capping inversion around 3000 feet.
Daytime heating should erode the cap enough this afternoon for CU
to thin down to FEW areawide. Southerly winds will continue
around 15 knots this afternoon, with a few gusts above 20kts.
Loss of daytime heating will bring winds down slightly, but a LLVL
jet caught underneath the cap will still be able to mix down to
the surface somewhat, keeping winds in the 10 to 15 knots range
overnight. Low clouds will again develop as well underneath the
cap. Breezy to windy conditions will develop tomorrow morning,
with winds reaching 20 knots and higher by late morning.
.PREV DISCUSSION... /issued 554 AM CST Mon Feb 27 2017/
DISCUSSION...Updated for latest aviation discussion below.
AVIATION...Increasing low level moisture has allowed some low
clouds to develop across Deep South Texas this morning. Will
continue to mention tempo MVFR ceilings through 13z. Otherwise,
VFR conditions expected through early this evening. Gusty south
to southeast winds later this morning will become breezy this
afternoon. MVFR ceilings will return later this evening and
overnight with IFR ceilings possible after 06z. South-southeast
winds above 10 knots should keep widespread fog from forming
PREV DISCUSSION... /issued 431 AM CST Mon Feb 27 2017/
SHORT TERM (Now through Tuesday): Well above normal temperatures
and generally rain-free conditions are expected through the forecast
period. A west southwest flow aloft and a 500 mb subtropical ridge
over the southern Gulf will continue to support a warm southerly
flow across region. Morning low clouds and patchy fog will mix out
by mid morning as winds increase. Weak low pressure near the Sierra
Madre this afternoon will keep winds fairly light across the west
with gusty winds near the coast today. High temperatures today will
be in the low to mid 90s, except for the 80s near the coast. Low
dewpoints (and RH dropping near 20 percent) expected across
Zapata/western Jim Hogg/western Starr counties this afternoon but
light winds will keep the wildfire behavior threat down. The low
level jet strengthens tonight which will keep wind speeds up to
preclude fog and also hold low temperatures tonight in the low 70s.
Tuesday will be the hottest day of the two with high temperatures in
the 90s away from the beaches, some triple digits are possible along
the river across the upper Valley.
LONG TERM (Tuesday Night through Sunday): The most active periods
of the long term portion of the forecast will occur on Wednesday
due to the passage of a cold front, and on Friday through Saturday
due to formation of a surface low pressure system over the coastal
waters of Tamaulipas that will then move south to north over Deep
South Texas and the Rio Grande Valley. Isolated convection is
anticipated with the former time period, with scattered showers
and thunderstorms expected for the latter. The frontal passage on
Wednesday, aided by cloud cover and precipitation later in the
long term forecast period, will aid in holding temperatures to
near normal levels for a change.
MARINE (Now through Tuesday): Buoy 42020 reported south winds
around 18 knots with gusts near 21 knots and seas of 5 feet with a
period of 6 seconds at 04 CST/10 UTC. Moderate south to southeast
winds will continue through the Tuesday as high pressure across the
Gulf interacts with weak lower pressure over the Sierra Madre. Winds
will increase tonight resulting in possible exercise caution
conditions on the Gulf waters overnight. Moderate seas expected
through the period.
Tuesday Night through Sunday: Small Craft Advisory winds and/or
seas will dominate through a majority of the forecast period due
to the passage of a cold front, followed by an enhanced surface
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