Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 150917
AFDBRO

Area Forecast Discussion
National Weather Service Brownsville TX
417 AM CDT Sun Apr 15 2018

.SHORT TERM (Now through Monday)...If you like cloudless skies,
pleasantly warm temperatures, and low humidity, the next two days
are for you! Today will be picture perfect in every sense of the
word as high pressure briefly settles in with light winds until the
afternoon sea breeze kicks up a few gusts between 2 and 4 PM,
continuing through 8 or 9 PM before settling back down again. With
dry air and generally dry soils after Saturday`s "flash" dry (strong
north winds combined with afternoon humidity in many areas between
10 and 15 percent), expect maximum dry adiabatic mixing allowing
temperatures to rise into the mid or even upper 80s in most
locations, most in line with the warmer ECMWF.

Clear skies again tonight with lowering but non-zero winds.  Still,
plenty of low level dry air will allow temperatures to gradually
fall back into the 50s for most - and with slightly higher winds
across the Rio Grande Plains values may be fairly uniform throughout
Deep South Texas...Harlingen through Falfurrias and the King Ranch
may be the cool spot while Zapata and Hebbronville end up a couple
degrees higher. For now have 56 to 58 in most locations.

Monday will see a quick kick-up of southeast winds.  Trends have
been for a breezy to perhaps even windy afternoon as gradient
tightens and full sunshine allows full mixing in the still-dry air.
While winds remain below advisory levels (30 gust 40), would not
surprised to see some periods of 25 gusting 35 mph just about
anywhere. For now, favored the mid Valley for the peak winds but
other locations are only a few knots behind.  Atmosphere begins its
warmup as well, but low level temperatures are just "cool" enough to
keep temperatures from soaring well into the 90s. Raised values
along lines of ECMWF which continues to handle the warming best, so
upper 80s to around 90 (west and north) cover it.

LONG TERM (Monday night through Saturday): An H5 ridge axis over
the central United States Monday will move east Tuesday as an H5
trough lifts across the northwest United States. At the surface,
high pressure across south Texas will move east as low pressure
develops on the lee side of the Rockies. Moderate to strong south
winds will create breezy to windy conditions across eastern
sections on Tues. A weak cold front is progged to move into south
and deep South Texas on Wednesday and Thursday, stalling over the
area and sparking a few showers as low level moisture continues
its upward trend. The next mid level ridge, moving over the area
and over the surface front, will inhibit strong weather. The
pressure gradient should weaken across the lower Texas coast as
well, resulting in weaker onshore winds. Another sharp shortwave
trough will dig across the Pacific Northwest Thursday, and the
resulting High Plains storm system that deepens into Thursday
night will bring breezy conditions to the CWA on Friday. A Pacific
front may move through the CWA on Saturday, sparking a brief
period of isolated to scattered showers and thunderstorms, but
ridging and dry air in its wake will quickly clear skies and bring
fair weather for the remainder of the weekend.

&&

.MARINE:

Now through Monday: If you`ve got a day to boat or fish, this is
your window. Winds and seas continue to drop quickly as high
pressure settles in this morning, with Laguna Madre nearly calm
and smooth while seas are only moderate with light winds over the
Gulf. That will remain the case through tonight, though afternoon
sea breeze may kick up winds toward 15 knot gusts over the Bay
today. Light but non-zero southeast winds tonight not enough to
make a difference for early morning boating/fishing trips Monday.
However, tightening pressure gradient quickly arrives by late
morning and early afternoon, with Laguna Madre winds possibly
poking 20 knots from time to time while Gulf winds hang back a bit
courtesy of the Marine layer. Seas will be slow to respond Monday
in the Gulf, remaining on the low end of the moderate level (3
feet or so).

Monday night through Thursday night: Low end small craft advisory
conditions may develop on the Gulf Monday night through Wednesday.
South winds will be moderate to fresh, resulting in seas reaching
around seven feet. High pressure over the Gulf will be interacting
with lower pressure over the Plains. A weak front approaching the
area on Wednesday will allow winds to decrease Wednesday night into
Thursday, but another Plains low pressure system will deepen Thurs
night, with increasing southeast winds and building seas.

&&

.Fire Weather:

Friday`s heat spike set the table for Saturday across areas west
of US 281, where Red Flags were running strong in 20 to 25 mph
wind combined with 80+ degree temperatures, humidity 10 to 15
percent, and dry to critically dry fuels. Today`s lighter winds
will reduce threat for rapid spread initially as humidity crashes
back into the teens west and 20s east. One thing to keep in mind
is the afternoon easterly sea breeze, which will be able to gust
close to 20 mph mainly along and east of US 281. Bottom line? Any
planned burns should be up and down by 2 PM before these winds
kick in, as erratic behavior could become problematic even though
parameters are below danger levels.

That situation changes on Monday. Aforementioned tightening
pressure gradient comes with remaining deep dry air which in the
past can create a critical fire weather day even in south to
southeast flow. ECMWF and NAM appear to handle the combination of
gusty winds and remaining dry air, which along with warming
temperatures to around 90 will push afternoon humidity to between
17 and 25 percent along/west of US 281. This time, 20 foot winds
have good potential to reach 20 mph (sustained) with 25 mph gusts
in all areas - and fuels will easily remain dry to critically dry,
particularly grasses and small brush. For all these reasons, have
issued a Fire Weather Watch for Brooks/Hidalgo west during the
afternoon Monday.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  81  59  83  67 /   0   0   0   0
BROWNSVILLE          83  58  84  66 /   0   0   0   0
HARLINGEN            84  56  86  64 /   0   0   0   0
MCALLEN              86  58  88  66 /   0   0   0   0
RIO GRANDE CITY      86  56  89  64 /   0   0   0   0
SOUTH PADRE ISLAND   78  62  79  69 /   0   0   0   0

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...Fire Weather Watch from Monday afternoon through Monday evening
     for TXZ248>250-252-253.

GM...None.

&&

$$

This product is also available on the web at:
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