Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 210715 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
215 AM CDT Sat Apr 21 2018

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

&&

.AVIATION...IR satl imagery shows some patchy mid level clds
moving over the region from west to east while areas of low level
clds are located around most of the RGV. Expect some of the low
level cld decks to our south and east to fill in gradually
throughout the overnight hours allowing the ceilings to drop down
to MVFR levels throughout the morning hours. The increasing
surface heating in combination with the strengthening SE low level
flow will mix out any MVFR ceilings that form up this morning
allowing for VFR conditions to prevail later today. The 500 mb
closed low moving across the region to our north may help fire up
some isold conv later in the current TAF period. However will not
incluee any mention of it in the current TAF wording as overall
converage will be too limited to seriously impact the RGV
airports.

&&

.PREV DISCUSSION... /issued 619 PM CDT Fri Apr 20 2018/

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...Surface winds are beginning to diminish with a few low
clouds in place right now. Moderate winds are expected overnight
as cloud cover increases and slips into MVFR territory. A return
to VFR will occur tomorrow as breezy winds prevail and cloud decks
rise.

PREV DISCUSSION... /issued 315 PM CDT Fri Apr 20 2018/

SHORT TERM (Tonight through Saturday Night): Upper-level low pressure
over the Four Corners region will continue to move eastward this
evening with broad diffluence in the mid layers through Saturday.
At the surface, winds are gradually shifting from the east to the
southeast today as higher pressure builds over the northern Gulf.
At the surface, a weak northward-moving boundary was evident on
radar and satellite imagery earlier. This was likely the cold
front that moved through yesterday, returning northward as a warm
front. No real impacts are seen with this front other than
increasing cloudiness across Deep South Texas. Shower activity has
been absent as moisture remains limited to near the surface. Dry
air above 850mb, especially over the RGV, will limit convection
through the night and into Saturday. Models are indicating very
low PoPs, which seems reasonable, but have kept mentionable
chances on Saturday with the upper low moving across North Texas
and moderate southeast winds bringing a bit more moisture in.
Temperatures today have been cooperating in the low to mid 80s
range, which is just about normal for this time of year. Highs
tomorrow may be a few degrees warmer with more of a southerly wind
component compared to today.

LONG TERM (Sunday through Friday): 500mb low/trough across
southeast Oklahoma Sunday will move eastward across
Mississippi/Alabama Monday. At the surface...a frontal system
across the Arklatex Sunday will bring a weak cold front into the
Rio Grande valley. Moisture appears too limited to mention rain
chances except across extreme southeast portions of the CWA
Sunday. Surface high pressure will build into south Texas in the
wake of the front Sunday into Monday. Low to mid level moisture is
expected to increase across northeast Mexico Sun night into Monday
but convection should remain well to the southwest of the area. A
surge of drier air is progged to move into deep south TX Tuesday
as 500mb ridge across northern Mexico and west TX provides
subsidence across south TX. The global models continue to bring a
500mb shortwave trough across the northern plains Tuesday into the
midwest and Ohio River valley Wednesday. A weak cold front is
expected to move into south TX Wed afternoon before stalling.
Moisture is progged to increase across the CWA Wed night into
Thursday but will not mention rain chances Thursday. A stronger
500mb shortwave trough is expected to develop and move across the
east-central U.S. Thurs night into Friday. The 12Z GFS brings a
cold front through the Rio Grande valley Friday providing a slight
chance of showers and thunderstorms across the area Thurs night
into Friday. There are some differences between the ECMWF and GFS
Wednesday and Thursday but they appear to be somewhat in
agreement on Friday so will adjust temperature model blends
slightly cooler towards the end of the forecast period as a
result.

MARINE (Now through Saturday): Higher pressure continues to build
over the northern Gulf, so winds are gradually shifting from the
east to southeast. Winds are a bit stronger on the bay waters, so
small craft should exercise caution this afternoon. Do not
anticipate any Small Craft Advisories, but winds may range from 15
to 20 knots on Saturday with moderate seas.

Sunday through Wednesday...Light south winds will shift to the
north and increase from the northeast Sunday as a weak cold front
moves through the coastal waters. Light northeast winds will
prevail across the western Gulf of Mexico Monday with surface
high pressure across south Texas and the western Gulf. The
pressure gradient will remain weak across the lower TX coast
Tuesday with surface high pressure across the western Gulf. Winds
will veer to the east but remain light Wednesday as a weak cold
front moves into south TX.

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&

$$

This product is also available on the web at:
HTTP://WEATHER.GOV/RGV

Short Term/Aviation...60
Long Term...63



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