Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 241129 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
629 AM CDT Mon Apr 24 2017

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

&&

.AVIATION...No change in the ongoing aviation forecast, as high
pressure keeps low clouds from forming, while a shortwave aloft
spreads high clouds across the region. Southeast winds will come
up to 10 to 15 knots later this afternoon, mainly along the coast,
and remain steady around 10 knots overnight tonight areawide.

&&

.PREV DISCUSSION... /issued 359 AM CDT Mon Apr 24 2017/

SHORT TERM (Today through Tuesday):Surface high pressure has
settled into south Texas this morning, with mostly clear skies and
Spring-like temperatures in the 50s. High cirrus spreading well
overhead due to a weak shortwave moving across the Big Bend region.
This will only serve to dim the bright sunshine expected today.
Highs will recover well this afternoon, reaching the 80s. Southeast
flow returns in the afternoon, and will continue through the night,
bringing Gulf moisture back into the region. Tuesday will see warmer
temperatures as the weak dryline tries to intrude on the western
counties. Highs will be in the 90s for most all but the immediate
coastal cities, with 100 degrees possible near Falcon Lake.

LONG TERM (Tuesday Night through Sunday):Mid level flow across
the Lower 48 during the long term will be dominated by a long wave
trough covering the Western two-thirds with blocking ridge off the
Southeast coast. While most of the active/adverse weather
(Tstms/snow) is expected across the Rockies and Plains, Deep South
Texas the RGV will see its share of sensible weather in form of
heat and wind. No rain is forecast for the long term with the
atmosphere staying relatively dry with west to southwest flow south
of the mean trough.

Wednesday looks like the hottest day of the week an intense
dryline extends south into the Rio Grande Plains from a deepening
Plains lows. Models suggest the dryline to move well east into the
Mid RGV with downslope NW winds in wake of the dryline and south
to southwest winds in advance of the low pressure trough. Expect
temperatures to soar through the afternoon with most locations
west of 69E exceeding 100 degrees. GFS MAV/MEX and ECMWF are
advertising some extreme numbers...GFS 106 for MFE, Edinburg
104...ECMWF 102 HRL, 99 BRO for example. Latest forecast
approaches some of these numbers but not confident enough to touch
them.

Surface winds shifts off the Gulf Wednesday night and Thursday as
the Plain states low/storm system lifts northeast allowing for the
dryline to retreat West and weak surface ridge settling over
northeast Texas. Temperatures retreat with near normal minimums
and not as Highs Thursday. A series of low pressure areas then
form along a quasi-stationary front over the front range and
Plains Friday and Saturday with the RGV wind machine and heat
cranking up. GFS/ECMWF show 850mb temperatures ranging from 26-29C
which can translate to surface temperatures well over 100 degrees.
Add in some higher dewpoints in the Mid and Lower Valley with a
more S-SE wind heat indices could approach or even exceed 110
degrees for the first time this year. Relief might be on the way
but we will have to wait until Sunday or Monday as the potential
stronger Plains storm system pushes a cold front through the
region.

MARINE:(Today through Tuesday): High pressure moving across the
northern Gulf will gradually turn winds back to the southeast during
the day Monday. Winds will generally remain around 10 knots, so seas
will remain 2 feet or less, with a minimal chop on the Laguna.
Southerly flow picks up quickly after midnight as the next low moves
across Oklahoma, interacting with the Gulf ridge. Winds will
increase to around 20 knots after midnight and continue through the
day Tuesday. Advisories are likely for the Gulf waters later tonight
and for all zones Tuesday.

Tuesday night through Friday...Winds and seas will be initially
adverse with possible SCA`s in effect Tuesday night into early
Wednesday strong surface low moves out of the Southern Plains and
into the Central plains. The moderately strong onshore flow
diminishes Wednesday and backs easterly Thursday as the pressure
gradient slackens with the approach of low pressure trough/cold
front over Central Texas. A stronger southerly flow becomes
reestablished Friday and Saturday with possible small craft
advisory conditions. No rain is expected this week.

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&

$$

This product is also available on the web at:
HTTP://WEATHER.GOV/RGV

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