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Area Forecast Discussion (AFD)

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

FXUS64 KBRO 200453 AAB

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1053 PM CST Tue Feb 19 2019

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

.AVIATION...Satellite images and surface observations indicate low
clouds with light rain and mist across the CWA late tonight.
Ceilings were near 300ft at most local aerodromes to near 1300ft
at KBKS. Visibilities were near 3SM with light rain/mist at most local
aerodromes to near 6SM with light rain/mist at KBRO. Expect IFR to
LIFR conditions across the Rio Grande valley the rest of tonight
through Wed morning before drier air filters into the area
tomorrow in the wake of a weak cold front moving through deep
south Texas late tonight. Expect ceilings/visibilities to improve
late Wed morning as drier air filters into the CWA. 

.PREV DISCUSSION... /issued 535 PM CST Tue Feb 19 2019/ 
DISCUSSION...Updated for latest aviation discussion below.

AVIATION...Satellite images and surface observations indicate low
clouds and mist across the CWA early this evening. Ceilings were
near 300ft at KPIL and KHBV to near 1200ft at KBKS. Visibilities
were near 1SM with mist at KHBV to near 5SM with mist at KEBG and
KAPY. Expect IFR to LIFR conditions across the Rio Grande valley
tonight into early Wed morning as the coastal low across the
northwest Gulf of Mexico moves northward and a weak cold front
moves across the CWA tonight. Ceilings and visibilities will
improve late Wed morning into early Wed afternoon as drier air
filters into the area.

PREV DISCUSSION... /issued 256 PM CST Tue Feb 19 2019/ 
SHORT TERM (Tonight through Wednesday Night): A low pressure area
will move north along the lower Texas coast through this evening,
with a surge of high pressure moving south into the back side of 
the low as a cold front over land, which will push offshore after 
midnight tonight. Low clouds with light rain and/or drizzle with 
fog will develop overnight and into Wednesday morning, especially 
near the coast, but drier air will move in by Wednesday afternoon,
clearing the area out from west to east, except possibly for the 
southeast corner of the CWA, the lower valley, with a temporary 
end to rain chances over land. However, by Wednesday night this 
latest front will itself turn into a coastal trough and start to 
move back up the coast, with increasing clouds Wednesday night, 
and a chance of light coastal rain. Lows will be in the 50s 
tonight and tomorrow night. High temperatures east will be 
suppressed on Wednesday due to the delayed/partial clearing, but 
high temperatures out west could reach around 70 degrees with 
light north winds.

LONG TERM (Thursday through Tuesday): Long term forecast is 
dominated by broad trough across the western US and modest ridge 
just off the east coast. This keeps south Texas in a general 
southwest flow pattern aloft, bringing impulses through the 
region, mainly just increasing cloud cover at times. With the main
storm patter away from Texas, the remainder of the week will see 
the dissipation of the coastal trough and return of southeast flow
at the surface. This will prompt a warming trend, with highs 
gradually returning to the 80s. The only larger system expected 
looks to be on Saturday, as a larger piece of the trough sweeps 
across the US, bringing a considerable Pacific front through. 
Timing still expected early Saturday morning, but lack of llvl 
moisture and better midlevel energy remaining further north, the 
front will have a hard time sparking shower activity. Have kept 
some modest chances for later Saturday, but trends have been 
downward recently, so confidence is not high. The southwest flow 
aloft will stall the tail end of the front offshore Sunday, 
transitioning to yet another coastal trough, continuing the mostly
cloudy pattern, and bringing a better chance for light rain and 
drizzle on Monday. After this, models completely diverge, with one
bringing in another front Tuesday, while another has no front in 
the entire state.

Now through Wednesday night: Swells/wave heights are slowly coming
down this afternoon as a low pressure area slash warm front moves
back north along the coast. Marine fog may be an issue near the
coast until north winds pick up late tonight. High pressure will
build south tonight with north winds increasing after midnight,
along with building seas. Low end small craft advisory conditions
will be possible Wednesday into Wednesday evening. Winds will veer
to east and weaken Wednesday night as a coastal trough sets up
again along the northeast Mexican coast and juts north into the
lower Texas coastal waters.

Thursday through Sunday: Weak coastal trough just off the
coastline Thursday keeps winds generally light and variable. The
trough finally dissipates, allowing modest southeast flow to 
resume for the day Friday. Saturday the next cold front sweeps
into the northwest Gulf, with a gradual shift to northwest winds.
Airmass behind this front is not a cold airmass, so winds behind
the front remain modest. Winds gradually shift northeasterly on
Sunday as the next coastal trough begins to wrap up to the



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