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Area forecast discussion 
National Weather Service Brownsville Texas
625 am CDT Tuesday Apr 28 2015

Discussion...updated for latest aviation discussion below.

&&

Aviation...leading edge of the front is moving across the area at
this time with most of the region under a northwest flow with gusts
up to 28 knots especially in Hebbronville and Zapata. The winds will
begin to increase even more in the next hour across the rgv allowing
patchy fog to dissipate. Expect an increase in winds up to 30 kts
through the day as the surge of high pressure moves into the
area. Ceilings will improve to VFR through the day with a few to
scattered high clouds streaming across the area. The gradient will
remain strong in the evening hours keeping gusty winds through
the evening and early night hours. Middle level cloud will be on the
increase overnight but will remain VFR.

&&

Previous discussion... /issued 327 am CDT Tuesday Apr 28 2015/

Short term /now through Wednesday/...the closed 500 mb low currently
over northern Texas continues its trajectory eastward today. Observation at
the surface show the leading edge of the front moving across south
central Texas near San Antonio with northerly winds gusty up to 25
knots. Closer to the region...in the wake of the front NE flow near
the coast is advecting moisture into the lower and Middle Valley which
is enhancing patchy to dense fog from pil west into bro...hrl and
Edinburg. Through sunrise...the northwest flow will begin to increase
as the front makes its way southward. That front will allow for much
dry air to filter into the County Warning Area diminishing the potential for broader
areas with dense fog. The gradient associated with this second high
pressure surging south is a lot stronger inducing the northerly flow
to increase through the day. The changes will begin early sunrise and
continue to pick up in the afternoon hours. As the low continues its
track east into NE Texas and Tennessee Valley by the end of the prd...dry air
aloft warp underneath this low will take control at the middle and upper
levels allowing for less cloud cover in the afternoon hours. Still some
lingering stratus will develop in the middle levels but it will mainly move
into the area by evening and overnight hours.

Tonight...due to the increase in cloud cover lean towards increasing low
temperatures one to two degrees as this cloud deck will limit radiational cooling
and keep temperatures in the upper 50s. As the dry air mass remains in place the
potential for rain is zero. Surface gradient remains tight through the evening
and overnight hours maintaining breeze conditions with gusty winds up to 15
knots the minimum.

Wednesday...the high pressure settles over the region with a much weaker
gradient and its centered near the Sierra Madre. The northerly winds will
begin to relax with weak ridge building from the west. Much more dry air
dominates the region with few to none cloud deck across south Texas. This
will allow for day time heating with abundant sunshine to warm up temperatures to
near 80s across the western counties and upper 70s near the coast.

Long term /Wednesday night through Monday/...500mb ridge across
the west central United States and a 500mb trough across the
eastern U.S. Will continue to provide subsidence across south
Texas Wednesday and Thursday before the upper ridge begins to
flatten across the southwest U.S. Friday. At the surface...high
pressure across the central U.S. Wednesday will settle across
south Texas and the western Gulf of Mexico Thursday. An onshore
flow will return Thursday night into Friday as the surface ridge
moves eastward. Low to middle level moisture across eastern Mexico
Saturday is expected to move northward into Texas through the
weekend into early next week as an upper level trough appears to
be developing across the Pacific coast Sunday into Monday. Will
mention a slight chance of showers and thunderstorms for the end
of the forecast period. Otherwise...dry conditions and slightly
below normal temperatures will prevail through the rest of the
week before humidity and near normal temperatures return for the
weekend.

Marine...
now through Wednesday...the second high pressure surge will make its
way south early in the morning increasing northerly winds across the Gulf and
Laguna early today. Small Craft Advisory have been issued for Laguna and Gulf waters as the seas
will also begin to build closet to 6 to 7 feet by the end of the day. Seas will
built even more this afternoon and into Wednesday as the pg remains strong across
the Gulf waters. The conditions slightly improve over the Laguna but the Small Craft Advisory is
expect to prevail through Wednesday. The winds begin to decrease Wednesday in
the afternoon as the gradient weakens and seas begin to subside
late Wednesday evening.

Wednesday night through Saturday...moderate north winds will
prevail across the coastal waters Wednesday night before the pressure
gradient relaxes across the western Gulf of Mexico Thursday. Light
north winds Thursday will veer to the southeast Friday as the
surface ridge across Texas moves eastward. Light southeast winds
Friday will increase Saturday as low pressure across northwest
Texas and high pressure across the southeast United States
increases the pressure gradient across the Lower Texas coast.

&&

Bro watches/warnings/advisories...
Texas...none.
GM...Small Craft Advisory for winds until 8 PM CDT this evening for
gmz130-132-135.

Small Craft Advisory until 7 am CDT Wednesday for gmz150-155-170-
175.

&&

$$

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