Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 300539 AAA

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1239 AM CDT Thu Mar 30 2017

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

.AVIATION...Satellite images and surface observations indicate
clear skies across the CWA late tonight except across the coastal
sections where low clouds/fog continues to develop. Ceilings were
near 1000ft at KBRO. Visibilities were near 5SM with fog at KPIL
to near 6SM with fog at KHRL. Expect MVFR conditions to continue
to develop across the coastal sections of the CWA late tonight
into early Thurs morning before a weak cold front moves through
the Rio Grande valley Thurs morning. Otherwise...VFR conditions
will prevail across the area tonight through Thursday. May see
some isolated showers develop across the lower TX coast Thurs
morning as the front provides a focus for low level convergence.

.PREV DISCUSSION... /issued 1000 PM CDT Wed Mar 29 2017/
DISCUSSION...Made a quick update to the temperature/dewpoint and
sky grids to reflect current observational trends. Also, removed
thunder from the grids for the overnight hours but kept the
mention of showers tonight. No other changes needed at this time.

DISCUSSION...Updated for latest marine discussion below.

MARINE...Southeast swell heights have increased across the Gulf
waters (20 to 60 NM east of Padre Island) late this evening. Have
issued a short Small Craft Advisory until Midnight for the far
offshore Gulf waters as a result. No other changes needed.

PREV DISCUSSION... /issued 641 PM CDT Wed Mar 29 2017/

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...Surface observations and satellite imagery shows some
low cloud decks along a weak pre-frontal surface trough over the
extreme southeastern tip of Deep South Texas this evening. VFR
conditions will likely prevail through late this evening, except
will mention a brief TEMPO at BRO due to some lingering MVFR
ceilings. Light and variable winds ahead of the next cold front
will allow patchy fog and low clouds to develop late tonight,
especially at HRL and BRO. VFR conditions are expected to develop
in the wake of the front Thursday morning as northerly winds

PREV DISCUSSION... /issued 330 PM CDT Wed Mar 29 2017/

SHORT TERM (Tonight through Thursday Night): Current radar and
satellite imagery depict a thin southeasterly-moving line of showers
along a weak surface boundary. A dry line is also evident across the
middle portions of Deep South Texas with dew points ranging from the
upper 60s and low 70s near Brownsville to the upper 30s in the
Ranchlands and Upper Rio Grande Valley. Winds shifted to the north
fairly quickly, which has kept temperatures from exceeding the lower
90s this afternoon. Tonight, a weak cold front associated with low
pressure in the Central Plains will move through the area early
Thursday morning with patchy fog possible along the coast where
moisture may recover ahead of it. Precipitation chances will be
limited, though, with upper level forcing being north of the area
and very shallow moisture available when the front arrives. Have
kept isolated PoPs for the early morning hours.

Behind the front, northerly flow will quickly return with breezy
conditions possible through the afternoon, especially near the coast
and over the marine areas. During the day temperatures will be near
normal for late March with highs ranging from the lower to middle
80s. Winds will diminish by sunset and shift back to the
south/southeast as surface high pressure moves across the northern
Gulf of Mexico, bringing a return of higher dewpoints Friday

LONG TERM (Friday through Wednesday): A deep mid level low will
be spinning over the four corners Fri, moving slowly east and
producing pressure falls over West Texas. This will keep the deep
South Texas wind machine on for the day, and will support warm
weather with high temps in the 90s. An eastward moving front
associated with the system will move across Texas on Saturday,
with stronger weather over East Texas and weaker, derivative
weather over the CWA Saturday afternoon. Upper diffluence may
destabilize the atmosphere upstream over the RGV Plains Sat night
and Sun morning, always a concern for this area, with showers and
thunderstorms indicated in the upcoming forecast. The mid level
trough axis will swing past on Sunday with drier air and upstream
ridging taking over Sunday night.

A mid level short wave trough will follow-up by diving out of the
Pacific Northwest and into the high plains Monday night, and
pressure falls over the plains will help local winds swing rather
quickly back to southeast. The main system will remain farther
north, over the Central Plains, with a cold front pushing into
Central texas, ahead of high pressure over the four corners
Tuesday night. That front may generate a few showers Wednesday
and Wednesday night, but mainly increased cloud cover.

MARINE (Now through Thursday Night): Winds have diminished this
afternoon across the Lower Texas Coastal Waters with a shift to
the north behind a weak southward-moving surface boundary. Only a
few showers are expected late this afternoon with dry conditions
expected tonight. With strong swells, seas have been much slower
to subside across the far offshore waters (20-60 NM) with a Small
Craft Advisory still in effect. Thursday morning, a weak cold
front will move across the marine areas, bringing isolated showers
or thunderstorms. Another Small Craft Advisory may be needed
behind the front with strong northerly winds expected through the

Friday through Monday: Southeast winds on the Gulf will be
moderate to fresh with elevated seas Friday through Sunday. Winds
and waves may rise above small craft advisory criteria at times. A
front will move into the area on Sunday, shifting winds to north
northwest Sun night, and marginal small craft advisory conditions
may continue on the Gulf into Mon morning. Winds will be less on
the Laguna during the period, though small craft should exercise
caution conditions will be possible at times. Winds will switch
back to mdt southeast quickly, by Monday night, and moderate seas
will persist.



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