045 
FXUS64 KBRO 061129
AFDBRO

Area Forecast Discussion
National Weather Service BROWNSVILLE TX
629 AM CDT Thu Oct 6 2016

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

&&

.AVIATION...Hit and miss low clouds have been drifting across TAF
site overnight and will likely continue through just after
daybreak. Winds have decreased a bit...but are expected to
increase from the ESE to E through the day with the seabreeze
front. There could be some isolated precipitation with the
seabreeze...however chances remain too low to mention in TAF
package at this time. 

&&

.PREV DISCUSSION... /issued 446 AM CDT Thu Oct 6 2016/ 

SHORT TERM (Today through Friday): Have made little in the way
of changes to the forecast for today and Friday. Model soundings
have come back with slightly deeper moisture profiles this
morning...with PWATS in the 1.7 to 1.8" range. While mention of
even slight chance showers seems optimistic for this
afternoon...weakened ridging aloft and some seabreeze forcing
could lead to possible precip and have left POPs the same. At the
very least...there should be a bit more cloud cover this
afternoon. That will keep temperatures a degree or two lower than
yesterday...even then highs today will be above normal.

For Friday...the upper level ridge begins to build over the region
again...however the surface pressure gradient will begin the tighten
with the the cold front moving through central Texas. Rainfall
chances will remain low on Friday as well as moisture levels never
increase substantially...with a generally seabreeze trend from east
to west. 

LONG TERM (Friday Night through Wednesday): 500 mb ridging will
gradually build over southern TX throughout late Friday into
Saturday and Sunday. This ridging will be eroded away somewhat as
a short wave from the Baja California area moves east into the
south central Plains states on Monday/Tuesday. This troffing will
gradually shift eastwards later next week with the ridge axis
shifts back to the west coast. A sharp 500 mb trough axis over the
Midwest will also shift east Friday night/Saturday. The passage of
this trough axis will drive a decent cold front down through the
RGV late Friday/early Saturday allowing for surface ridging to
build over the region. Both the ECMWF and the GFS have backed off
a bit on the conv potential throughout the longer range forecast
period as both models are reflecting less deep layer moisture
advection on through Day 7.  

In the wake of the frontal passage there will be the potential for
the development of some weak coastal troffing later next week.
However the limited moisture advection in the longer range period
may limit the conv potential out over the offshore waters. 

The GFS and ECMWF 500 mb fields are on the same page for the most
part on through around Tuesday. The longer range models then start
diverging with the GFS maintaining more of a 500 mb ridge over the
RGV with the ECMWF placing the ridge axis much further west. 

The model differences concerning high temps over the longer term
period continue with the ECMWF coming in much warmer versus the
GFS. Since we expect the ridge axis will weaken some throughout
the longer range period will opt for a model blend for temps
leaning towards the cooler side of guidance through Day 7 with
the pops going below guidance.

Overall confidence in this forecast remains around average due to
the continuing differences with the GFS and ECMWF guidance. 

MARINE (Now through Friday): Low seas of 2 to 3 feet and light
to moderate SE to E winds will continue on Thursday. A tightening
pressure gradient will begin on Friday with a cold front
approaching from central Texas. Seas will increase to 2 to 4
feet...with winds becoming E to NE and increasing to 15 KTS.

Friday night through Monday night...A moderate northeast surface
flow will prevail along the lower Texas coastline throughout the
weekend which may push the Gulf conditions up near SCEC or
marginal SCA criteria through around Sunday with the surface flow
starting to weaken on Monday allowing for the winds and seas to
decrease. 

&&

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

$$

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

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