Preview of NWS' New Version of Forecast
This preview is not operational and should not be used for support decisions.

Area Forecast Discussion (AFD)

Issued by Brownsville/Rio Grande Valley, TX (BRO)

                            
524 
FXUS64 KBRO 220706 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
206 AM CDT Sun Apr 22 2018

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

&&

.AVIATION...The cold front to our north is pushing south and is
approaching the CRP area early this morning with no pcpn located
along the front. As the cold front approaches the RGV later this
morning expect MVFR/IFR ceilings to spread out ahead of the front.
As it moves through the region around sunrise expect the ceilings
to improve back to VFR levels later today and this evening as
drier air moves into the region from the north. Some patchy fog 
may form across the RGV airports for a few hours ahead of the
front as the surface winds weaken and become more variable.
However am not confident enough of the timing and location of the
fog to include it in the current TAF issuance.  

&&

.PREV DISCUSSION... /issued 645 PM CDT Sat Apr 21 2018/ 

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...MVFR is prevailing right now and is expected to
persist through the overnight hours. A cold front will sweep
through the aerodromes around sunrise Sunday, with veering 
winds. Surface winds will continue to veer and increase as 
Sunday progresses, with VFR anticipated to return. 

PREV DISCUSSION... /issued 253 PM CDT Sat Apr 21 2018/ 

SHORT TERM (Now through Sunday Night): An upper level low will 
move across the central plains through the weekend. An associated 
surface low will move across north central Texas, bringing a weak 
cold front through the area on Sunday morning. 

Ahead of the front, isolated showers continue to impact the eastern 
half of deep south Texas with mostly cloudy skies. Shower chances 
will decrease tonight as northwest winds in the low-levels bring 
much drier air to the region. Winds will diminish tonight ahead of 
the front with patchy fog possible overnight. Winds will shift out 
of the northeast behind the front Sunday morning with gradually 
clearing skies in the afternoon and evening. Temperatures remain 
warm with cooler overnight temperatures Sunday night due to drier 
air and clearing skies. Model guidance indicates that dew points 
could drop into the lower 40s in the upper ranchlands where 
temperatures may drop into the upper 50s. 

LONG TERM (Monday through Saturday): Models are fairly in good
agreement with the 500mb low/trough across the southeast United
States Monday. A 500mb ridge across northern Mexico and the
southwest U.S. will provide west to northwest flow across south
Texas Tuesday. A 500mb low is progged to develop across the
northern plains Tuesday and move southeast towards Missouri
Wednesday. The upper level low is expected to move southeast into
the southeast U.S. as a shortwave trough Thursday. There are some
differences between the GFS and ECMWF on timing of this feature.
As a result...there are differences on the timing of a weak cold
front moving into south Texas Wednesday and moving into the Rio
Grande valley Wed night into Thursday. Moisture will increase
across the area Wed night into Thursday regardless of the timing
of the front so will mention a slight chance of showers and
thunderstorms across the CWA Wed night into Thursday. Models
continue to diverge on moisture across the area Friday with the
ECMWF wetter than the GFS and has another weak cold front moving
into the area with strong convection moving across the Rio Grande
valley. Will mention a slight chance of showers and thunderstorms
for Friday. The rest of the forecast period depends on whether a
front does move through deep south TX Friday providing lingering
moisture across the RGV Saturday and northeast flow at the surface
in combination with clouds providing slightly cooler temperatures.
Will go with a blend of model guidance for temperatures and POPS 
Wed night through Saturday.

MARINE (Now through Sunday night): Moderate to strong southeasterly 
winds across the coastal waters this afternoon will diminish tonight 
with the approach of a weak cold front. Winds will shift out of the 
north at 15 to 20 knots behind the front on Sunday morning. Seas 
will remain elevated through Sunday before improving Monday
morning.

Monday through Thursday...Light east to northeast winds will 
prevail across the coastal waters Monday with surface high 
pressure across south Texas and the western Gulf of Mexico. The 
pressure gradient will remain weak across the lower TX coast 
Tuesday. Light east to southeast winds will prevail across the 
western Gulf Tuesday. Winds will veer to the southeast briefly on 
Wednesday before backing to the east Wed night as a weak cold 
front approaches the coastal bend. The front may move through the 
coastal waters late Wed night/Thurs morning. Winds will shift to 
the northeast but remain light in the wake of the front. 

&&

.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