Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 172320

Area Forecast Discussion
National Weather Service Brownsville TX
620 PM CDT Tue Oct 17 2017

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


.AVIATION...VFR conditions to prevail through the period as
surface high pressure remains over Deep South TX. North to east
winds 10 knots or less early this evening will become light and
variable by 02Z where they will remain so through late Wednesday
morning. Northeast to east winds 12 knots or less to prevail
roughly between 18Z-00Z Wednesday afternoon.


.PREV DISCUSSION... /issued 220 PM CDT Tue Oct 17 2017/

SHORT TERM (Tonight through Wednesday Night): Broad ridging will
stretch upstream along the Rio Grande with high pressure over the
northwest Gulf. Ridging will begin to break down and shift east
late in the period as a short wave trough deepens and digs into
the southwest United States. It looks like a bit of moisture will
move west under the ridge over the west Gulf, bringing a few
showers into the marine areas Wednesday night, a trend that will
continue into the long term. Moisture will slowly return over the
short term, with dew points edging back into the lower 60s by
Wednesday night. The higher dew points, along with still light
winds and mostly clear skies might be enough to support patchy fog
across the ranchlands and brush country, but not looking for a
major fog event just yet. Lows tonight will be in the 50s, but
we`ll see 80s across the area on Wednesday, and 60s for lows
Wednesday night.

LONG TERM (Thursday through Tuesday): Gradually recovery from
current "cold snap" continues through the remainder of the week as
H5 ridge shift east across he Gulf and a weak trough sweep across
northwest Texas. The surface ridge will also shift east, further
opening the way for Gulf moisture to return to the valley.
Temperatures will gradually climb to around 90 into the weekend,
with enough surface moisture and instability to spark a few
afternoon showers. Main forecast question revolves around the
next cold front, currently scheduled for Sunday. Models have been
fairly consistent on timing of the front late afternoon/early
evening, but are all over the place regarding rainfall
possibilities and overall strength of passage. GFs has flipped its
stance in the past 24 hours, and is now leaning towards a
completely dry passage for Deep South Texas. But it is the outlier
in this regard, so have held onto a chance for rainfall with the
passage, focused sometime Sunday. Once the front is through,
models are similar in that the rain will end quickly and slightly
cooler temperatures will filter in Sunday night into Monday. A
reinforcing area of surface high pressure is shown in the main
models arriving Tuesday, which would bring an additional piece of
cooler weather well into next week.

Tonight through Wednesday Night: High pressure extending
southwest into Texas and the local area will shift east in the
short term. Winds will generally remain light to moderate, with
low to moderate seas. Winds will veer to east Wednesday night. A
few showers may sneak into the Gulf waters from the east Wednesday

Thursday through Sunday: Modest onshore flow begins to increase
Thursday as a longer fetch develops across the northern Gulf. This
will kick seas up to 5 to 6 feet offshore and may bring another
round of coastal flooding issues for the weekend. Not yet
expecting marine advisories for the end of the week, as forecast
seas not quite reaching advisory thresholds. Sometime Sunday, the
next front is expected to sweep across the northwest Gulf. Timing
is still somewhat of a question, but north winds will arrive
sometime during the day. Models have backed off of the north winds
behind the front, so seas are not forecast to jump after passage.
The front is expected to bring areas of showers and thunderstorms
as it passes.




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