Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 191706 AAB
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1206 PM CDT Wed Jun 19 2019

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

&&

.AVIATION...Current VFR conditions under sunny skies with
moderate to breezy southeast winds. VFR conditions will persist
the rest of today with surface high pressure in control. A few
high clouds will be possible. Recurring morning low clouds will
develop again on Thursday, with brief periods of MVFR ceilings
possible.

&&

.PREV DISCUSSION... /issued 629 AM CDT Wed Jun 19 2019/

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...Only change to the previous suite of TAFs was to
indicate MVFR at MFE in initial conditions. Otherwise, VFR will
generally continue to be the rule. Moderate to breezy surface
winds are also expected.

PREV DISCUSSION... /issued 358 AM CDT Wed Jun 19 2019/

SHORT TERM (Now through Thursday): 500 mb high pressure will remain
centered along the east coast of Mexico and extended over Deep South
Texas and the Rio Grande Valley. As a result of the proximity of the
mid-level high, heat will be an issue during this portion of the
forecast. A Heat Advisory is in effect this afternoon for the entire
inland portion of the BRO CWFA except the immediate coastal portions
of Cameron, Willacy, and Kenedy counties. Another Heat Advisory is
likely on Thursday. The mid-level ridge will also serve to produce
dry weather with no opportunity for rain expected.

LONG TERM (Thursday night through Tuesday): Mid-level high
pressure will dominate the pattern for much of the long term
period, leaving little room for heat relief or rainfall across
Deep South Texas. Starting at the end of the week, 500mb ridge
axis will gradually move eastward across the Gulf of Mexico, with
a series of shortwave troughs digging across the Four Corners
Region and into the Central Plains. Most of these waves will
remain well to the west or north from the CWA, but it will lead to
breezy to windy conditions each day. MOS guidance consistently
shows sustained winds exceeding 25mph across the lower RGV from
Friday night through the early part of next week. Will have to
monitor LLJ trends for a possible Wind Advisory, particularly on
Saturday.

The main story will be the heat. Maintaining most of what the
previous forecast had, we are looking at possible Heat Advisories
with dangerous heat indices, mainly from Friday through Sunday.
Afternoon high temperatures will range from 95 to 100F across the
eastern half of Deep South Texas (minus the coast) and from 100
to 107F across the western half. Models keep dew points relatively
high with strong SE flow and more modest moisture from 850 to
700mb. Therefore, less mixing of dry air may lead to heat indices
of 110 to 115F, and possibly locally higher. For what it`s worth,
we may also be looking at record high minimum temperatures
(historically-warm mornings). For BRO, we are currently
forecasting record high minimum temperatures Saturday, Sunday and
Monday.

Though most locations won`t see much rainfall, we can`t rule out
a slight chance of convection that may roll off of the higher
terrain of Sierra Madre Oriental, due to terrain differences and
weak shortwave troughiness existing. Surface flow may be too
strong for much of a seabreeze, but low (10-20%) rain chances
will occur Sunday into Tuesday for the RGV with slightly deeper
moisture available.

MARINE (Now through Thursday): Buoy 42020 reported south winds
around 14 knots gusting to around 16 knots with seas slightly under
3.5 feet with a period of 6 seconds at 250 CDT/750 UTC. Increasingly
adverse marine conditions are anticipated along the Lower Texas
Coast due to an intensifying pressure gradient. Small Craft Exercise
Caution and Small Craft Advisory for Winds are likely to be needed
at times for the lower Texas coastal waters.

Thursday night through Tuesday: Hazardous marine conditions can be
expected through the long term period, as a series of storm
systems in the Plains and troughing across West Texas results in
strong southeast winds across the Western Gulf of Mexico. Small
Craft Advisories will be likely through early next week for all of
the lower Texas coastal waters. By mid-week next week, the fetch
appears to wane a bit, which may improve conditions across the
Bay, but small craft will likely need to exercise caution.

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...Heat Advisory until 7 PM CDT this evening for TXZ248>255-353.

GM...None.
&&

$$

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