Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Brownsville Texas
652 am CDT Wednesday Apr 1 2015
Discussion...updated for latest aviation discussion below.
Aviation...current bro radar shows isolated showers across deep
south Texas this morning. Will mention vcsh at valley airports
this morning but will hold off on the mention of thunderstorms in the vicinity for now.
Latest satellite images and surface observations indicate high
cirrus streaming overhead with low cloud decks across portions of
deep south Texas. Ceilings were near 900 feet at bro and around
1200 feet at t65/ebg with VFR ceilings elsewhere. Will mention a
tempo at hrl and mfe for breaks in the ceilings resulting in brief
VFR skies. Cloudy skies will continue today with ceilings rising
by late morning into the afternoon. Breezy conditions expected
again later today with sustained winds of 15 to 20 knots with
gusts around 25 knots. Winds decrease this evening with MVFR
ceilings late this evening and possible IFR ceilings overnight.
Previous discussion... /issued 423 am CDT Wednesday Apr 1 2015/
Short term /now through Thursday/...current water vapor imagery
shows a middle to upper shortwave trough over northern Mexico near the
Texas Big Bend. Bro radar shows ongoing virga/elevated shower
activity across northern tamaulipas. This activity is associated
with the disturbance approaching the region from the west. This
activity will move across the Rio Grande River in the next few
hours. Latest hrrr indicates that the heaviest activity may impact
portions of Starr and Hidalgo counties now through sunrise. Light to
moderate southeast winds prevail across the area this morning
courtesy of surface high pressure over the eastern Gulf of Mexico.
The bro 0z sounding shows an abundance of drier air...especially
between 650 to 850 mb with an inversion around 1900 feet. This
inversion along with the southeast flow advecting Gulf moisture into
the lower levels has allowed low stratus to develop across deep
south Texas and patchy fog across portions of the Rio Grande Valley
this morning. Temperatures will remain steady in the upper 60s to
lower 70s through sunrise.
Low clouds and patchy fog will lift by middle morning as southeast
winds increase. The weak 500 mb trough will move overhead from west
to east today. This will generate a slight chance of showers and
thunderstorms across the Rio Grande Valley with a chance of
convection across the northern ranchlands today. Will lean towards
the super blend for probability of precipitation today...which is close to the latest
met/mav and ecwmf MOS. The Storm Prediction Center has all of deep
south Texas in a general thunderstorm outlook for today. High
temperatures today will be in low to middle 80s...except for the 70s
along the beaches...due to the abundant cloud cover and some shower
activity. Moderate to breezy southeast winds can be expected across
the region today.
The weak 500 mb trough moves east of the area tonight with partial
clearing possible from west to east. Low temperatures tonight will
range from the upper 60s across the ranchlands to the lower 70s near
the coast. Light southeast winds will prevail under partly to mostly
The middle-level flow becomes more zonal on Thursday which will ensure
dry weather across deep south Texas for Thursday. Abundant sunshine
will allow for very warm conditions across the area for Thursday.
High temperatures will range from the middle to upper 70s along the
beaches...low to middle 80s across the low to Middle Valley and the upper
80s to around 90 across the Upper Valley and the west. Moderate to
breezy southeast winds will prevail across the region on Thursday.
Long term /Thursday night through Tuesday/...the most significant
weather feature to affect deep south Texas and the Rio Grande
Valley in the long term portion of the forecast will be the
passage of a cold front during the very early pre-dawn morning
hours of Saturday. The passage of the front...and the subsequent
and brief formation of an inverted surface trough of low pressure
along the Lower Texas coast...will produce generally scattered
showers and thunderstorms from Friday night through Sunday.
Otherwise...the remainder of the long term forecast period will be
dry. Temperatures will be tempered to well below normal levels on
Saturday due to the passage of the front...with near to above
normal temperatures for the remainder of the forecast period.
Marine...now through Thursday...latest marine observation platforms
indicate light to moderate southeast winds prevail along the Lower
Texas coast this morning. Buoy 42020 currently shows seas near 3.9
feet with southeast winds around 18 knots. A few showers and
thunderstorms may develop later today as a upper level disturbance
moves overhead. The interaction between high pressure over the
Gulf of Mexico and a low pressure across West Texas will create
moderate to breezy winds and moderate to rough seas for the Lower
Texas coastal waters today through Thursday. Small craft exercise
caution conditions is likely on the Laguna Madre each afternoon
and over the Gulf waters tonight.
Thursday night through Tuesday...small craft exercise caution will
likely be needed along the Lower Texas coast Thursday night through
Friday night in advance of the very early Saturday morning passage
of a cold front. Small Craft Advisory winds and/or seas are likely
Saturday and Saturday night due to the passage of the front. Strong
winds and rough seas will persist Sunday through Tuesday due high
pressure over the Gulf of Mexico interacting with low pressure in
the Central Plains...with additional small craft exercise
cautions and small craft advisories likely for that time period.
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