Area Forecast Discussion
Issued by NWS Brownsville, TX
FXUS64 KBRO 250903
Area Forecast Discussion
National Weather Service BROWNSVILLE TX
403 AM CDT SAT JUN 25 2016
.SHORT TERM (Today through Sunday): Tropical moisture continues
to increase across the region courtesy of deep southerly flow
between the large upper low over North Central Mexico and Broad
mid level high pressure across the Southern Gulf Coast. Last
evenings sounding indicated 1.88 inches of precipitable water with
the GFS continue to forecast pwats nearing 2.25 inches today. The
abundant tropical moisture to combine with increasing upper
diffluence and lift associated with the northward moving upper low
leading to scattered showers and thunderstorms across the entire
Rio Grande Valley. The convection is starting this morning and is
expected to increase through the afternoon with the daytime
heating. Some thunderstorms will produce brief heavy rain with
isolated nuisance flooding where one of the heavier thunderstorms
may persist for a while. Expect for temperatures to lower 3 to 5
degrees over the last few days with several layers of clouds
Sunday...NAM, GFS and ECMWF all move the upper low farther north
with mid and upper level winds turning southwest to west cutting off
the tropical moisture feed. At the surface drier air also gets
entrained across Deep South Texas which will allow for rain chances
to drop into the 10-20 percent for Sunday. Can not rule out some
streamer showers Saturday night and maybe an isolated shower over
the coastal and central counties Sunday. Temperatures rebound a few
degrees over today with less overall cloudiness.
.LONG TERM (Sunday Night through Friday): Forecast has changed
minimally for the upcoming week as the upper trough dissipates,
but surges of moisture continue to arrive off the Gulf. This
arriving moisture will enhance the seabreeze enough to spark
shower activity, especially Monday and again Wednesday.
Temperatures will fluctuate only slightly through the week, with
slightly cooler conditions Monday before the H5 ridge begins to
exert more influence on south Texas. Most of the remainder of the
week will be dry, with temperatures soaring near 100 degrees.
The moderate onshore flow to slowly relax later today and tonight
with seas gradually subsiding through Sunday as an upper level low
moves farther north and surface high pressure weakening across the
Gulf of Mexico. Showers and a few thunderstorms today to
decreasing in coverage Sunday.
Monday through Friday: More modest winds and seas are forecast for
the upcoming week, with southeast flow generally around 10 knots.
The lighter wind field will bring calmer seas to the northwest
Gulf, generally running 2 feet or less throughout.
.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL 91 79 91 77 / 30 10 10 10
BROWNSVILLE 92 78 93 77 / 40 10 10 10
HARLINGEN 94 77 95 77 / 40 10 10 10
MCALLEN 95 77 97 76 / 30 10 10 10
RIO GRANDE CITY 98 76 100 75 / 30 20 10 10
SOUTH PADRE ISLAND 87 79 87 81 / 30 10 10 10
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