Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 121732 AAA

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1232 PM CDT Thu Oct 12 2017

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

.AVIATION...Satellite images and surface observations indicate
some mid to high level clouds across northern and extreme western
portions of the CWA early this afternoon. Ceilings were near
3600ft at KAPY to near 4500ft at KBKS. Expect VFR conditions to
prevail across the Rio Grande valley and the northern ranchlands the
rest of the afternoon into this evening with surface high
pressure across east Texas extending into deep south Texas. MVFR
conditions are expected to develop late tonight into early Fri
morning as patchy fog develops with clear skies and light winds.
In addition...a surge of low to mid level moisture will move
across the coastal sections of the CWA Fri morning providing low
clouds and light rain showers across the lower TX coast.

.PREV DISCUSSION... /issued 635 AM CDT Thu Oct 12 2017/
DISCUSSION...Updated for latest aviation discussion below.

AVIATION...Brownsville radar continues to indicate some
convection across portions of the Rio Grande Valley and the lower
Texas Gulf waters. Expect a mix of VFR/MVFR ceilings through the
mid-morning hours with ceilings dropping to around 2500 feet at
times. Full VFR conditions expected by this afternoon as slightly
drier air moves overhead. Light northwest winds this morning will
turn to the northeast and east by late this afternoon.

PREV DISCUSSION... /issued 357 AM CDT Thu Oct 12 2017/

SHORT TERM (Today through Friday): Brownsville radar continues
to indicate some convection across the Gulf waters extending south
of the Rio Grande River with patches of stratiform rainfall
across Cameron county. The combination of a stationary frontal
boundary across the northwest Gulf of Mexico and a coastal trough
across the western Gulf of Mexico will provide scattered showers
and isolated thunderstorms along the lower Texas coast today. The
coastal trough weakens by this evening as the surface flow becomes
easterly late this afternoon. Rain chances will diminish late
this afternoon and tonight as drier air moves overhead. However,
low level moisture will remain in place as deep easterly flow
continues resulting in coastal showers tonight and sea breeze
convection on Friday. Near normal temperatures expected today with
warmer than normal temperatures tonight and Friday.

LONG TERM (Friday Night through Wednesday):

The long term begins with an elongated upper level high centered
across the southeast US, basically stretching across the Gulf
States and off the Atlantic Coastline. As the surface, easterly
flow is expected, which should help the daily sea breeze surge
inland. Although the sea breeze may spark a few diurnal
showers/storms, think that much of the area will remain dry as the
upper high overall limits POPs.

The high will eventually pinch off and slide westward across
northern Mexico. Globals are still bringing a cold front through
the region on Monday as an upper level trough begins to slide
eastward into the southeast. This should increase rainfall chances
early next week, however, we did cap POPs just a bit for
uncertainty in strength/sharpness of the frontal boundary as well
as very subtle differences among medium range models. A cooler
and drier airmass should begin to filter into the region shortly
after the frontal passage. Although high pressure will be largely
in control, there will be some coastal troughing influence, which
may keep some rain chances at the very least in the outer extent
of the marine zones.

MARINE: (Now through Friday): A weak coastal trough across the
western Gulf of Mexico will continue to produce showers and
thunderstorms across the lower Texas coastal waters today. Light
to moderate northeast winds this morning will diminish and become
easterly this afternoon. Light east winds and low seas will
prevail across the lower Texas coastal waters through Friday.

Friday Night through Wednesday): This weekend will be rather
benign in terms of marine weather for the deep south Texas waters.
Pressure gradient will have relaxed a good bit allowing for winds
and seas to calm somewhat. That said, a cold frontal boundary
will begin to slide southward Monday. Northeast flow behind the
front will gradually increase through the day Monday and remain
strong through early Tuesday. With this northeasterly flow,
expect seas to respond with wave heights approaching Small Craft
Advisory levels.

Finally, high pressure will begin to move southward by Tuesday.
Flow will weaken a bit, however, moderate winds and elevated seas
may be possible into midweek next week as moderate northeasterly
flow continues.



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