Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 201730 AAB

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1130 AM CST Sat Jan 20 2018

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


.AVIATION...Fog has lifted at all locations finally, but low cloud
deck remains right in the vicinity of KMFE. Satellite trends show
clearing should arrive there within an hour. KBRO and KHRL are
mostly clear, with few to sct daytime cu expected to develop
through the afternoon. Breezes just off the surface have been
able to mix lower for areas without cloud cover, so winds around
15kts should continue through the day. Surface winds will remain
elevated through the night as the llvl jet increases aloft.
Breezes should keep fog from thickening tonight, but some light br
still possible, but too low confidence to add to TAFs yet.


.PREV DISCUSSION... /issued 529 AM CST Sat Jan 20 2018/

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...LIFR is prevailing at the aerodromes right now
courtesy of dense fog. Conditions will improve around mid-morning
and especially this afternoon due to increasing sunshine and
surface winds. Moderate surface winds tonight should prevent the
formation of fog, with MVFR cloud decks.

PREV DISCUSSION... /issued 320 AM CST Sat Jan 20 2018/

SHORT TERM Now through Sunday): Fog is the main concern right now.
Surface observations indicate that visibilities have dropped within
Deep South Texas and the Rio Grande Valley over the past several
hours, and in-situ web cameras suggest that visibilities may be low
enough to warrant a Dense Fog Advisory for portions or all of the
inland section of the BRO CWFA. Will make a decision on the Advisory
before the official forecast is generated. Otherwise, 500 mb high
pressure will transition from west to east across the Lone Star
State as closed 500 mb low pressure follows closely on its heels
over the Four Corners area. This pattern will lead to reduced cloud
cover with dry weather during the forecast period. An intensifying
onshore flow will result in rapidly warming temperatures from today
to tomorrow, and the intensity of the onshore flow may be such on
Sunday that a Wind Advisory may be needed for the three immediate
coastal counties. Will monitor model trends and see how that shakes
out over the next 24 hours.

LONG TERM (Sunday Night through Friday): The next cold front
(from a milder source region) arrives Sunday night bringing
slightly cooler and drier air behind it. Some showers will be
possible with the front Sunday night into Monday morning, mainly
near the coast and across the Gulf waters. Rain-free conditions
are expected Monday and Tuesday as surface high pressure settles
across deep south Texas. Rain chances begin to increase Tuesday
night and Wednesday as a surface trough/coastal low develops and
interacts with an approaching upper level disturbance. Rain
chances diminish Thursday night into Friday as the next mid level
short wave moves east and surface high pressure builds into the
region. Near normal temperatures are expected through late next
week. Another 500mb short wave trough digs into the southwest
United States next weekend and pushes the associated cold front
into the region Saturday night.

MARINE: (Now through Sunday): Buoy 42019 reported south-southeast
winds around 19 knots gusting to around 23 knots with seas slightly
under 6 feet with a period of 6 seconds at 02 CST/08 UTC. Strong
surface high pressure over the Gulf of Mexico will interact with a
cold front that will move into Texas during the period. Winds will
likely be strong enough, and seas high enough, to warrant a Small
Craft Exercise Caution for the Lower Texas coastal waters,
especially the Gulf of Mexico. However, a Small Craft Advisory for
Winds may be needed in lieu of the Small Craft Exercise Caution on
Sunday for the Laguna Madre.

Sunday Night through Wednesday Night:  A cold front will move
through the lower Texas coastal waters late Sunday bringing moderate
north winds and moderate to high seas Monday and Monday night.
Marine Conditions will improve Tuesday and Tuesday night as high
pressure spreads across the area. Northeast winds will increase
Wednesday and Wednesday night as surface high pressure across the
northwest Gulf interacts with surface low pressure in the western
Gulf. Periods of Small Craft Should Exercise conditons to low end
Small Craft Advisory conditions likely Sunday night through
Wednesday night.




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