Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 211145 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
645 AM CDT Mon Sep 21 2020

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

&&

.AVIATION...Surface obs from the RGV indicate that some MVFR
ceilings have formed up/moved in over the HRL and BRO areas. MFE
remains VFR for now, but believe that some of these MVFR ceilings
may move over MFE for a few hours this morning. The latest 06Z BRO
sounding shows a pretty dry and stable atms in place over the RGV.
So expect any MVFR ceilings to remain pretty short lived this
morning with VFR conditions likely returning pretty quickly. Some
of the conv associated with TS Beta could possibly edge SW towards
the RGV, but believe that these areas of conv will be too sparse
to justify including in the 12Z TAF issuance.

&&

.PREV DISCUSSION... /issued 515 AM CDT Mon Sep 21 2020/

SHORT TERM (Now through Tuesday): KCRP radar is showing an area
of rain from the west side of TS Beta pushing WSW into the Coastal
Bend area. This area of rain and others associated with Beta will
likely continue edging into the northern Ranchlands throughout
the short term period. However, the airmass over the RGV is very
dry with KBRO indicating a PWAT of 1.13 inches. So expect that the
rain may be eroded away as it moves into the drier air near the
RGV. This will tend to limit pops near the Rio Grande. TS Beta is
expected to continue moving WNW into the mid to upper TX coastline
as 500 mb ridging prevails over the central and eastern Gulf.
Expect a pretty tight moisture gradient to prevail over the region
with some better tropical moisture advecting across the northern
Ranchlands as Beta continues pushing WNW throughout today and
Tues. So will maintain some isold/sct showers/t-storms across the
northern counties throughout the short term.

Since the low level winds will generally blow out to the W-NW with
the center of Beta positioned to our NE. This will allow temps to
start warming. The latest NAM/GFS and ECMWF short range temp
guidance show this gradual warm up and will go close to a model
consensus for temps through Tues.

Social Media reports from SPI indicate that there are multiple
reports of flooded city streets, including Padre Blvd. Water level
reports from the tide gauge at Brazos Santiago on SPI show that
current observed tides are running 2.25 feet above normal predicted
tide levels. So have extended the Coastal Flood Warning, High Surf
Advisory and High Rip Current Risk through 12z Tues.

LONG TERM (Tuesday Night through Sunday): Generally dry weather
is anticipated through the period, with very little to no chance
of rain. This weather scenario will be the result of abundant
moisture associated with Tropical Storm Beta being transported off
towards the northeast in association with the tropical system,
leaving a drier airmass in its wake. With expected limited rain
chances and associated cloud cover, warming and above normal
temperatures will also occur during the entire forecast period.

MARINE (Now through Tuesday): Buoy020 reports swells of 13 to 14
feet offshore this morning with no indication that they will be
subsiding anytime soon as Beta takes its time to move inland to our
north. So will maintain the Tropical Storm Watch across GMZ155-175
and an SCA for GMZ150-170. The elevated swells from Beta will start
to decrease towards Tues morning as Beta finally moves inland and
weakens.

Tuesday Night through Sunday: Light to moderate winds and low to
moderate seas will prevail along the Lower Texas Coast during the
period with surface high pressure becoming more dominant over the
western Gulf of Mexico. Small Craft Exercise Caution may be needed
for a portion of the lower Texas coastal waters Tuesday night and
Wednesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  86  71  90  72 /  10  10  10  10
BROWNSVILLE          87  71  91  72 /  10  10  10   0
HARLINGEN            86  70  90  70 /  10  10  10   0
MCALLEN              86  71  90  71 /  10  10  10   0
RIO GRANDE CITY      88  69  92  69 /  10  10  10   0
SOUTH PADRE ISLAND   83  75  86  76 /  10  10  10  10

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...Coastal Flood Warning until 7 AM CDT Tuesday for TXZ256-257-351.

     High Rip Current Risk through Tuesday morning for TXZ256-257-351.

     High Surf Advisory until 7 AM CDT Tuesday for TXZ256-257-351.

GM...Small Craft Advisory until 7 AM CDT Tuesday for GMZ150-170.

     Tropical Storm Watch for GMZ155-175.

&&

$$

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


Short Term/Aviation...Speece-60
Long Term/Graphics...Tomaselli-66
Tropical/HTI...Mejia-67
Upper Air...Adams-55



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