Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 190546 AAB

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1246 AM CDT Thu Apr 19 2018

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


.AVIATION...Surface observations and satellite imagery indicate a
mix of low to mid level cloud decks across deep south Texas early
this morning. VFR ceilings should continue for the next few hours
before MVFR ceilings develop across the region before sunrise as
moisture increases. VFR conditions expected to return late this
morning into the afternoon as northeast winds increase.


.PREV DISCUSSION... /issued 643 PM CDT Wed Apr 18 2018/

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...VFR ceilings continue into tonight before a weak
front works into the Rio Grande Valley. Breezy winds will
diminish towards midnight and remain light through Thursday
morning before picking up Thursday afternoon at HRL and BRO. With
increasing moisture, expect MVFR ceilings to build into the
region around midnight and continue through Thursday afternoon
with isolated showers.

PREV DISCUSSION... /issued 259 PM CDT Wed Apr 18 2018/

SHORT TERM (Now through Thursday night): Satellite imagery was
showing considerable cumulus over the eastern half of the forecast
area as a weak cold front and upper level short wave were
approaching from the north. This cold front will enter the
northwestern portion of the forecast area late this afternoon and
slowly sag southward across the northern tier of counties before
dropping further southward overnight tonight into Thursday
morning. As the front progresses southward, moisture will pool up
and deepen east of the Sierra Occidental (Mexican) Mountains. Lift
associated with the slowly progressing front will combine with
the moisture for the development of isolated showers mainly over
the northwest half of the forecast area late tonight/Thursday

Clouds will be widespread across the region most of the day on
Thursday as substantial tropical moisture remains in place and
combines with weak lift left over from the weak cold front that will
eventually wash out over the area during the day on Thursday. High
temperatures in the afternoon will range from the lower 80s over the
southern tier of counties with mid 70s to near 80 over the north.
Skies will remain cloudy Thursday night with slight chances of
showers mainly over the western half of the forecast area.

LONG TERM (Friday through Wednesday): 500mb low across the Four
Corners region at the end of the week will slowly open as it moves
east southeastward across the Southern Plains this weekend.
Across South Texas, flow will be mostly zonal but models do
indicate modest diffluence, more so over Central and East Texas
Saturday afternoon. At the surface, a low will develop near the
Panhandle and move across North Texas, bringing a sagging front
southward during the day on Sunday. The combination of the
surface boundary and vicinity of the upper-level low will bring
a chance of showers and thunderstorms through the weekend with the
best chance being Saturday afternoon when the trough axis moves
across the region. There is a slight concern for a few stronger
storms, especially in the northern counties. Model soundings do
show a substantial capping inversion, but surface convergence and
upper level support may overcome that.

The cold front should move through on Sunday, bringing some CAA
behind it, but the main temperature difference will be seen in the
mornings through mid-week with drier air filtering in from the
north. Surface high pressure will slowly move southeastward,
maintaining a northerly component to the wind for a couple days.
Winds will shift back to the southeast by mid-week with low rain
chances each day.

MARINE (Now through Thursday night): Latest observation from Buoy
42020 as of 200 pm CDT indicated SE winds around 10 kts and seas of
5-6 ft. Will need to continue the Small Craft Should Exercise
Caution headline for the Gulf waters into the evenings hours due to
elevated seas. Late tonight and early Thursday morning, a weak cold
front will enter the northern waters and cause winds over the north
to increase to close to SCEC levels Thursday morning through the
afternoon. Winds will once again diminish Thursday night as the
pressure gradient associated with the weak cold front weakens.

Friday through Monday: A long easterly fetch of winds across the
Gulf waters will maintain elevated seas of 4 to 6 feet into this
weekend. The gradient will slightly relax on Sunday ahead of the
next front with stronger northeast winds moving in behind it.
Small Craft Exercise conditions will be possible Friday and




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