Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus64 kbro 270902 

Area forecast discussion
National Weather Service Brownsville Texas
402 am CDT Thu Jul 27 2017

Short term (now through friday): ample moisture remains in place
across deep south Texas this morning, with GOES sounder noting precipitable water
value around 2.1 inches still. Main difference between yesterday
and today will be the departure of the inverted trough as it
drifts west underneath the dominant US ridge. As the ridge builds
in, some drier air will return to the region between 5000 and
10000 feet. This will help cap off the atmosphere through most of
the day, keeping convection minimized. Highs will yet again reach
the upper 90s and low 100s for the region. Forecast precipitable water values will
be down to near 1.5 inches by dawn Friday, continuing the dry and
hot forecast. Highs will tick upwards a few degrees Friday, with
100 degree temps reaching to the us77 corridor.

Long term (friday night through wednesday):long term forecast
remains on track with models consensus in good agreement and
consistency. A very hot and dry weekend is in store then hopefully
a slight temperature reprieve as the chance of rain continues to
ramp up next week.

The mid-level 500mb ridge expands across the western states and
Texas while a strong mid level trough digs along the eastern
Seaboard. A cold front, associated with the eastern trough, works
its way unusually far south moving into the northern Gulf of
Mexico late Sunday/Monday with fair agreement among the GFS,
Canadian and European model (ecmwf) pushing the weakening front into our coastal
waters Tuesday. Moisture to begin to increase as early as Monday
but with higher moisture content in the vicinity of the frontal
boundary Tuesday looks like the best chance of rain for most
areas. With plenty of uncertainty on this front, since it is the
end of July and fronts are not very common this time of year, will
continue to broad brush pops at 20 percent Monday through
Wednesday. Temperatures peak this weekend with McAllen possibly
seeing one or two records being broken while Harlingen and
Brownsville look to be below record levels, but none the less the
heat will be on. As mentioned, some reprieve in the heat next
week as the chance of rain increases. Heat indices to remain just
below advisory levels (110+) this weekend with dewpoints lower
then usually with the building ridge and increased subsidence. As
surface moisture increases though next week and the isolated
nature of the rain chances could spell out higher hi numbers.


Marine:(now through friday): winds have steadily decreased across
the Gulf waters overnight, allowing seas to begin to relax. Lighter
southeast flow today and tomorrow will remain near 10 knots, keeping
swells 3 feet or less through the period. Drier air return aloft
later today, ending any rainfall threat through the rest of the

Friday night through Monday...weak surface ridge over the Gulf
waters to settle over the western Gulf this weekend while a weak
cold front works its way into the western Gulf next week keeping
the pressure gradient weak. Light to occasional moderate southeast
winds this weekend becoming east later Monday and Tuesday.
Relative rainfree conditions Saturday and Sunday with isolated
to scattered showers and thunderstorms next week are anticipated
with the approach of the front.


Preliminary point temps/pops...
Bayview/Port Isabel 93 78 95 79 / 10 10 10 0
Brownsville 94 78 95 79 / 10 10 10 0
Harlingen 97 77 99 78 / 20 10 10 0
McAllen 100 78 103 78 / 20 10 10 0
Rio Grande City 102 76 105 77 / 10 10 10 0
South Padre Island 88 81 88 81 / 10 10 0 0


Bro watches/warnings/advisories...


This product is also available on the web at:

National Weather Service Glossary of Abbreviations