270 
FXUS64 KBRO 042013
AFDBRO

Area Forecast Discussion
National Weather Service Brownsville TX
313 PM CDT Sun Aug 4 2019

...The Heat Builds This Week as the Dog Days of August
Intensify...

.SHORT TERM (Tonight through Monday Night): Another hot summer day across 
the region out there with surface high pressure generally in control 
of our weather. Although the high is in control, sea breeze activity 
has yet again developed generally right along the I69E corridor from 
Cameron to Kenedy Counties. PWAT values in this area are between 1.5-
2" so a brief heavier shower or two is not impossible, but certainly 
the exception rather than the rule. Think this activity could get as 
far west of I69C but, CAMs or more specifically the ARW want to keep 
the better rain chances across the coastal counties for now. Blended 
HRRR/ARW with globals through the near term period. 

A warm/humid night is expected, but as stated high pressure is 
mostly in control so after diurnal heating think that overall rain 
chances drop significantly, especially the further inland you go.

Monday looks very similar to today, however, a bit drier air may 
nose into the region. This will lead fewer showers/convection so 
decided to drop POPs for much of the inland areas. Did keep some 
mention in the coastal counties where there is a nonzero prob for 
precip. Beyond this there is very little change in the short term 
period. Synoptics are very similar to days prior with the dominant 
high pressure across the Desert Southwest. Hot conditions continue 
with mostly light winds through the forecast period. 


.LONG TERM (Tuesday through Sunday): The story continues to be the
classic position and intensity of the "La Canicula" 500 mb ridge,
which re-centers over southern/western New Mexico through
Chihuahua state (Mexico) Tuesday...then eases into southwest 
Texas through Coahuila state Thursday. The ridge center then
stretches east and southeast into south and central
Texas...bringing even drier (and perhaps a touch hotter) air with
it, including across the Rio Grande Valley. 

As the upper ridge stretches southeast, a slightly stronger
surface high in the central/eastern Gulf will develop with it
while the thermal trough ("heat low") intensifies a bit each
afternoon/evening in the lee of the Sierra Madre. This will return
the summer version of the Valley Wind Machine (moderate and gusty
southeast winds by day and fresh evening/overnight breezes)
beginning Wednesday and continuing through the weekend.  

Increasing sunshine and lowering dewpoints especially west of US 
77 will bring even higher temperatures but allow humidity to fall
a bit, which should keep heat index values in check in the 105 to
110 range most afternoon...hot but not to the point of heat
advisory (111 or higher) issuances. Actual temperatures will
continue to climb the ladder, likely peaking Thursday through
Sunday with triple digits in all areas except mainly east of US
77. Upper 100s (107/108) are possible across the upper Valley and
Rio Grande Plains during this time.

For the beach, expect some level of upwelling to develop later in
the week and into the weekend but intensity of the surf
temperature drop remains to be seen. Either way, cooler waters
against the hotter than average land should cut winds 10 to 20
mph (lower) at the beach than in the "wind machine" areas each
day.

One more issue to be aware of late this week is the potential for
elevated fire danger across the Jim Hogg/Starr/Zapata and perhaps
Brooks County area beginning as early as Thursday and becoming 
more pronounced Friday through the weekend. 20 foot winds should 
reach 15 to 20 mph with higher gusts all three days in these areas
and there is a possibility for afternoon humidity to fall into 
the teens which could push values toward Red Flag Warning 
conditions.


&&

.MARINE: (Today through Monday): Favorable marine conditions expected 
through the short term with generally less than 2 ft wave heights 
expected. Winds should also be generally less than 10 knots, which 
will limit overall wave heights. Can't rule out a stray shower or 
T'storm, however, this looks to be the exception rather than the 
rule. 

(Tuesday through Friday Night)...The gradually building gradient
will increase overnight winds on the Gulf and afternoon winds on
the Bay...with caution conditions (15 to 20 knots and gusty)
likely arriving Wednesday and persisting through the end of the
week. Seas in the Gulf will become moderate due to the nighttime
winds (and initial daytime winds over pre-upwelled water) and
winds could reach caution overnight across the Gulf beginning
Wednesday night, dropping back with diurnal trends to 10 to 15
knots by day. Wavewatch is a bit slow to respond seas...so 4 feet
could arrive a bit sooner than forecast but should occur at some
point between Wednesday night and Friday.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  80  93  81  95 /  10  20  20  10 
BROWNSVILLE          80  96  80  97 /  10  20  20  10 
HARLINGEN            79  98  78 100 /  10  20  10  10 
MCALLEN              80 100  81 102 /  10  20  10  10 
RIO GRANDE CITY      79 102  80 103 /  10  10  10  10 
SOUTH PADRE ISLAND   82  89  83  90 /  20  20  20  10 

&&

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

$$

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

Short Term...55/RF
Long Term...52/BSG
Marine...55/52
Graphic Update/Addition...52/BSG