Area Forecast Discussion
Issued by NWS Brownsville, TX

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438
FXUS64 KBRO 221743 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service BROWNSVILLE TX
1243 PM CDT MON AUG 22 2016

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

&&

.AVIATION...mid level high pressure to build over the Western Gulf
and Eastern Texas increasing the subsidence across the region.
Much drier mid level air to keep any chance of rain close to zero.
VFR conditions to prevail with daytime cumulus field to dissipate
overnight and reform mid to late morning as low level moisture
remains sufficient for sct daytime clouds between 3000-5000 feet.
Surface winds remains gusty near 25 knots this afternoon before
decoupling this evening becoming light overnight. Southeasterly
winds to rebound with daytime mixing Tuesday with gusts slightly
lower expected to be around 20-22 knots.

&&

.PREV DISCUSSION... /issued 654 AM CDT MON AUG 22 2016/

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...The convection that impacted the northern counties a
few hours ago has moved north out of Deep South TX leaving behind
general VFR conditions for all three RGV airports. As the 500 mb
ridging from the Gulf of Mexico builds west over the Texas
coastline over the next 24 hours expect the drier and more stable
airmass to maintain VFR conditions for most of the upcoming TAF
period. Some brief reductions of visibilities down to MVFR levels
may be possible late in the TAF period due to lingering boundary
layer moisture.

PREV DISCUSSION... /issued 419 AM CDT MON AUG 22 2016/

SHORT TERM (Now through Tuesday): KBRO radar shows some scattered
showers and thunderstorms over mainly the northern counties this
morning. This convection is due to lingering moisture and
instability in place over the region as indicated by the 00z BRO
sounding which showed a PWAT of 2.11 inches and a CAPE of 4444 j/kg.
Short term model guidance showed some weak 500 mb PVA moving from
south to north over the region providing some decent divergence
aloft. The 500 mb ridging in place over the Gulf of Mex should build
west today and Tuesday which will dry out and stabilize the atms
over the region reducing the conv chcs. As the 500 mb ridging builds
over the region temps should warm up a bit through Tuesday as the
1000-500 mb thicknesses increase and the diurnal heating builds.
Will lean a little above temp guidance mainly on highs through
Tuesday.

LONG TERM (Tuesday Night through Sunday): A strong...broad upper
level ridge of high pressure will centered across the northern
Gulf to start the long term period. This system will keep much
drier air and subsidence across Deep South Texas through Thursday.
The ridge will begin to retreat north into the SE CONUS by Friday
and a more easterly flow regime will return. Somewhat deeper
moisture levels and weak impulses or troughing will approach the
region Friday and through the weekend. With better on-shore
flow...do expect any initial precipiation to be generated by the
seabreeze. Showers and isolated thunderstorms will be more hit and
miss in nature especially for Friday and Saturday. Slightly
higher moisture values and a deeper inverted trough will begin
moving across the Bay of Campeche on Sunday. Have left Sunday with
the highest chances for rainfall...but still only around 20 to 30
percent for now.

As far as temperatures...have continued the trend of above normal
readings given the magnitude of the high pressure and dry air
available for mixing down.

MARINE:

Now through Tuesday: The PGF over the western Gulf of Mexico and
the lower Texas coastline looks to weaken a bit through Tuesday
despite the surface high in place over the Gulf waters. This may
allow the winds and seas to weaken slightly through the short
term. A light to moderate s-se surface flow will prevail with seas
staying below SCA criteria through Tuesday.

Tuesday Night through Friday Night: Strong upper level high
pressure will dominate the northern Gulf waters through the
period. South to southeast winds will remain generally light to
moderate as broad surface high pressure over the Gulf keeps the
pressure gradient relaxed. Seas may remain more moderate through
Wednesday given the possibility of a longer SSE fetch and any
subsequent swell. However...seas will become low...generally 2
feet or less through Friday.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  94  80  93  80 /  10   0  10   0
BROWNSVILLE          96  79  95  79 /  10   0  10   0
HARLINGEN            98  78  98  78 /  10   0  10   0
MCALLEN             101  79 101  79 /  10   0   0   0
RIO GRANDE CITY      99  77 100  78 /  10   0   0   0
SOUTH PADRE ISLAND   90  82  88  81 /  10   0  10   0

&&

.BRO Watches/Warnings/Advisories...
TX...None.
GM...None.
&&

$$

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