Area Forecast Discussion
Issued by NWS Brownsville, TX

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41
000
FXUS64 KBRO 191142 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
642 AM CDT Fri May 19 2017

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

&&

.AVIATION...Low clouds are once again dissipating early this
morning and have opted to add a brief TEMPO group to cover
periodic MVFR cigs over the next couple of hours. VFR conditions
should then prevail for the better part of the day before low
clouds return this evening and overnight. Meanwhile, gusty SE
winds will continue across the area through day.

&&

.PREV DISCUSSION... /issued 427 AM CDT Fri May 19 2017/

SHORT TERM (Now through Saturday): The large cut-off H5 low
continues to meander across the Four Corners region early this
morning. Meanwhile, high pressure continues to dominate the Eastern
Gulf, with the RGV still generally under it`s influence. Today will
be similar to yesterday, with no rainfall expected, but with the
above normal temps and rather humid conditions continuing. Winds
will also be breezy to gusty, but do not expect any significantly
high winds.

The strong H5 low will move across the Central Rockies and into the
Plains States tonight and early on Saturday. The trailing cold front
will move south through Texas but will likely stall/stop just north
of the Ranchlands. Weak surface troughing will form along it and
there will also be some weak perturbations moving through the nearly
zonal flow aloft. Since there has been moisture return across the
region, do expect that some small chances for showers and
thunderstorms will be possible on Saturday. However, these chances
will generally be across portions of the Northern and Western
Ranchlands where there is better influence from the stalled boundary
and higher terrain. There could be some isolated stronger storms
Saturday afternoon. Otherwise, have kept the RGV dry in this time
frame with a mix of sun and clouds. Temps might be a couple of
degrees cooler then previous days where precip and more cloud cover
is expected in the Western Ranchlands. However, highs in the RGV
will continue to be in the lower to upper 90s.

LONG TERM (Saturday Night through Thursday):A broad long wave
trough over much of the CONUS and two cold fronts moving into
South Texas will keep the weather for the long term somewhat
unsettled. The first front will be edging into the NW Ranchlands
Saturday night/Sunday with best forcing and moisture residing in
the vicinity of the front. Consistency among the latest models
continue to trend with highest pops north and west of the the Mid
and especially Lower Rio Grande Valley which does not bode well
for the drought conditions. Storm Prediction Center also continues
with a wide berth of a marginal risk of severe thunderstorms
throughout the CWA Saturday night into early Sunday but with
expecting the most concentrated and strongest convection over the
Sierra Madre and in the vicinity of frontal boundary the Western
Counties will see the best chance of any strong to marginally
severe thunderstorms. The Boundary lingers in the area Sunday into
Monday morning before retreating as a warm front Mon afternoon.
Rain chances to tapper off Monday as the front retreats northward
as both GFS/ECMWF are in good agreement with this trend.
Temperatures trend downward near normal with some more lowering in
the west Sunday/Monday depending where the front ends up and how
fast it retreats.

Tuesday looks to be a relatively dry and warmer day with the next
upstream front moving into North Texas and a flat pressure
gradient across South Texas. A strong mid level ridge builds over
the intermountain west driving a strong shortwave south along the
west side of the broad trough over the Midwest/Northeast.
This highly amplified pattern drives a cold front through Deep
South Texas Tuesday night/Wednesday morning. Both GFS/ECMWF are in
good agreement with this setup and frontal timing. Will continue
with an increasing chance of rain and show a nice one day drop in
temperatures. Surface high pressure shift quickly east and
southeast winds return along with the front which might keep a
slight chance of rain at least in the morning.

MARINE:(Now through Saturday): Current conditions at Buoy 42020 at
3 AM show SSE winds of 12 to 15 knots and seas near 7 feet. Higher
seas will continue through the early afternoon and have extended the
Small Craft Advisory for the Gulf Waters until 1 pm. Meanwhile, the
pressure gradient will tighten once again today and winds will
increase across the Laguna Madre later this morning and through
early evening and a Small Craft Advisory for winds will be issued.
Both winds and seas will continue to improve Friday night into
Saturday as the surface pressure gradient weakens and a weak cold
front moves south into Southern Texas, but stops just north of the
Lower Texas Coastal Waters.

Saturday night through Tuesday...Pressure gradient will be
weakening early in the longer term with a weak cold front possibly
moving into the northern coastal waters early Sunday morning.
A general light easterly flow is expected Sunday with winds
returning southeast at moderate speeds as the front retreats
northward. Moderate southeast wind and seas continue Tuesday in
advance of a stronger front which looks to surge through the
coastal waters Wednesday with a moderate northeast winds. Small
craft advisories are not anticipated over the weekend and early
next week.

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...Small Craft Advisory for winds until 8 PM CDT this evening for
     GMZ130-132-135.

     Small Craft Advisory for hazardous seas until 1 PM CDT this
     afternoon for GMZ150-155-170-175.

&&

$$

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

69/59



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.