Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Brownsville Texas
358 am CDT Wednesday Jul 23 2014
Short term /Wednesday through Thursday/...strong 600 Dam Ridge
at 500 mb dominates most of the Desert Southwest while weak low
over the northern Gulf Coast retrogrades slowly westward through
the short term period. Quiet weather will prevail today with light
to moderate winds and dry conditions. Latest water vapor imagery
shows a stream of dry middle-level air moving across the region
keeping deep south Texas hot and dry. High temperatures will warm
up into the middle to upper 90s along the coast and the triple digits
out west with heat index or "feel like" temperatures between 105 to 108
today. Conditions begin to change a bit tonight as the middle level
low and its associated moisture gradually moves into the area.
This will enhance a few isolated showers over the Gulf waters and
gradually progress inland into early Thursday. Low temperatures
will remain in the upper 70s and in the 80s along coast.
Unfortunately for US...the low will be fighting the upper ridge
and it looks like this feature will be somewhat stretched or
sheared as it heads toward our corner of the world. Still though
..low-level moisture is expected to deepen with precipitable
water values peaking around the 2 inch mark. This may result in an
enhancement of the seabreeze by the time Thursday rolls around.
High temperatures will rise between 100 to 104 degrees west of
Highway 77 and upper 90s along the coastal counties. Heat index
values will range between 102 to 106 Thursday.
Long term /Thursday night through Tuesday/...the long term
forecast will be focused on the struggle between the strong
summertime ridge to the west and the stationary trough stretching
southward across the northern Gulf. A piece of the trough breaks
off and wraps westward around the southern edge of the ridge
across south Texas Friday. With precipitable water values still indicated at 1.8
inches...should be just enough instability and moisture to spark a
few showers along the seabreeze during the afternoon. After
Friday...the trough drifts further east...allowing the ridge to
build across south Texas. Moisture decreases...with precipitable water values
falling well below normal for this time of year. This will shut
off rainfall chances for the region through the middle of next
week and allow temperatures to continue to climb...with temperatures
about 5 degrees above where they should be this time of
year...with heat index values 105 to 110 each afternoon. Hot any
way you slice it.
Marine...Wednesday through Thursday...strong high pressure
dominating most of the Desert Southwest will keep a weak surface
pressure gradient over the Gulf waters today and Thursday allowing
for southeast winds to remain light over the Gulf waters. Seas will
be between 2 to 3 feet and less than 2 feet into Thursday. The ridge
will begin to build and shifts eastward shifting winds more easterly
into Thursday. An area of low pressure over the northern Gulf Coast
will retrograde westward and weaken but a few isolated showers could
still develop Thursday over the Gulf waters.
Thursday night through Sunday...the weekend marine forecast looks
reasonable for boaters as southeast winds generally run around1 5
knots...producing seas no higher than 4 feet with a long period. A
few showers are possible Friday morning with a midlevel
disturbance...but rain chances end for the weekend.
Preliminary point temps/pops...
Bayview/Port Isabel 94 78 94 78 / 10 10 20 10
Brownsville 96 78 96 78 / 10 10 20 10
Harlingen 98 76 98 76 / 10 10 20 10
McAllen 101 77 101 78 / 10 10 20 10
Rio Grande City 102 78 102 79 / 10 10 20 20
South Padre Island 90 79 90 79 / 10 20 20 10
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