FXUS64 KBRO 181108 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
608 AM CDT Tue Aug 18 2020

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

.AVIATION...Satellite images and surface observations indicate
some high clouds moving across the CWA early this morning. Expect
VFR conditions to prevail across the Rio Grande Valley the rest of
the morning into the afternoon even though low to mid level
moisture will remain high across the northern ranchlands as a weak
500mb vorticity center across southwest Texas moves southward.
&&

.PREV DISCUSSION... /issued 356 AM CDT Tue Aug 18 2020/
SHORT TERM (Today through Wednesday): A weak MCV across southwest
Texas will move southward into deep south Texas today providing a
slight chance to chance of showers and thunderstorms across the
northern and western portions of the CWA this afternoon as a
residual outflow boundary/frontal boundary north of the area
provides a focus for low level convergence. Low to mid level
moisture will remain high across the area tonight into Wednesday.
Will mention a slight chance of showers and thunderstorms across
western portions of the CWA this evening before the loss of
diurnal heating. Will also mention a slight chance of showers and
thunderstorms across the Rio Grande Valley and northern ranchlands
Wednesday before drier air aloft and subsidence increases Wed
afternoon with the 500mb ridge across the western United States
and the 500mb trough across the southeast U.S. extending into the
Gulf of Mexico.

LONG TERM (Wednesday Night through Monday): Effects of strong
mid-level ridging over the Intermountain West will continue to
spread over Deep South Texas to start the long-term period.
Forecast models remain in good agreement that height falls will
occur over much of southern and eastern Texas through the first
half of the period as a modest H5 trough/cut-off low develops over
the lower Mississippi Valley. Its trough axis will remain well
east of the CWA, keeping a dry, subsident, northerly flow aloft in
place into the start of the upcoming weekend. However, the
influence of the trough edging over eastern/southern Texas will
lower 1000-500mb thicknesses & H5 heights and should help cool
daytime temperatures down a couple of degrees on Friday and
Saturday. Forecast confidence begins to drop beyond Saturday as
model solutions diverge.

The National Hurricane Center (NHC) continues to monitor and
investigate two tropical waves in the Atlantic/Caribbean Sea, with
further development likely for both over the next 5 days, as they
continue to move west-northwestward. Although there is still lots
of uncertainty of what these two disturbances will do, model
consensus continues to show deep tropical moisture advecting into
south Texas on Sunday and Monday, increasing cloud cover and
precipitation chances. Residents of Deep South TX and the RGV
should continue to pay close attention to the latest
statements/outlooks from NHC concerning the progress of both of
these potential systems over the rest of this week and this
upcoming weekend. (www.nhc.noaa.gov)

MARINE (Today through Wednesday)...Seas were near 1.6 feet at
buoy020 at 2:40am and near 2 feet at buoy002 at 2:50 am. Winds were
from the east to northeast near 4 knots at buoy045 at 1:00am. Light
and variable winds will prevail across the coastal waters today as
weak high pressure across south Texas provides a weak pressure
gradient across the lower Texas coast this afternoon. Light and
variable winds will continue across the coastal waters tonight into
Wednesday as the pressure gradient remains weak across the lower
Texas coast.

Wednesday night through Sunday: A weak pressure gradient will
continue to keep marine conditions very favorable through the
remainder of the week, with generally light S or SE winds and low
seas. The pressure gradient may strengthen somewhat this weekend,
allowing for a little stronger SE or E winds and slightly higher
seas around 2 to 3 feet. However, neither Small Craft Exercise
Caution conditions nor Small Craft Advisories are anticipated
through Sunday.
&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  94  76  95  77 /  10  10  10   0
BROWNSVILLE          96  77  98  78 /  10  10  20   0
HARLINGEN            97  76  99  75 /  10  10  10   0
MCALLEN              97  77  99  77 /  10  10  20   0
RIO GRANDE CITY     101  77 101  76 /  10  20  20   0
SOUTH PADRE ISLAND   88  80  89  80 /  10  10  10  10
&&

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

$$

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

61-Castillo/67-Mejia