Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Brownsville Texas
359 am CST sun Dec 28 2014
Short term /now through Monday/...upper low pressure trough over
western Texas to traverse Texas today reaching the coastline around
6 PM. Widespread rain and much cooler weather is expected this
morning before drier air filters into south Texas late this
afternoon and tonight eventually pushing the rainfall east of the
region. High pressure settles over the County Warning Area tonight and Monday with
much improved weather.
Today...a roller coaster of weather is in the offering in the short
term with much cooler and wetter weather today. A morning of rain
with deep overcast conditions along with a brisk north winds will
push maximums 25 degrees colder then yesterdays. Southwest flow at or above
850mb overriding the denser cold air at the surface to combine with
a surface wave or low pressure area along the cold over the western
Gulf. This will strengthen the atmospheric lift over much of south
Texas providing the area with a good drenching of rain. Probability of precipitation values
remain very high with most areas seeing rain this morning with a few
heavier down pours and possibly a brief thunderstorm along and east
of Interstate Highway 69e/77. The rain tappers off west to east as
the upper trough steadily tracks eastward.
Tonight...upper trough moves offshore and drier air filters. Surface
low moves well east with the upper support and southwest weakens and
veers more westerly cutting off the overrunning. High pressure
builds overhead...skies clear allowing ND temperatures fall. Model
guidance in good agreement with upper 30s to lower 40s County Warning Area wide so
will not deviate much from these values.
Monday...high pressure to shift steadily eastward with the next
trough already moving into the northern rockies and intermountain
west. Winds to turn easterly by afternoon with slow recovery of
moisture with a deep layer of dry above 850mb. Plenty of sun
expected across the County Warning Area with some late afternoon cumulus build up
later in the afternoon. Temperatures to rebounding 10 to 15 degrees
with middle to upper 60s most locals.
Long term /Monday night through Saturday/...overall...messy. A
series of disturbances riding overhead with a west-southwest to
east-northeast middle-level flow...combined with the formation of an
inverted surface trough of low pressure over the western Gulf of
Mexico...will lead to scattered to numerous showers and patches of
light rain from Tuesday through Thursday night. Given the expected
abundant cloud cover and relatively high chances of precipitation...
below normal temperatures for the daytime and overnight hours are
likely...with daytime high temperatures possibly a few degrees too
warm given the also expected north to northeast winds. However...
time exists to adjust these downward in the near future...if
necessary. The development and quick exit of a weak area of low
pressure will actually bring reduced rain chances...an onshore
flow...and warmer temperatures for Friday...with the passage of
another cold front expected on Saturday.
Marine...now through Monday...low pressure to form along the cold
front that moved through last night strengthening the pressure
gradient. Northwest to north winds to remain strong and even
increase into the early afternoon with seas steadily building
upwards to 8 feet. Small craft advisories to remain in effect for
all coastal waters including the Laguna Madre. Winds over the
Laguna could diminish by 3 PM as the upper trough approaches the
Texas coast accelerating the surface low eastward weaken the
gradient along the immediate coast. The higher winds and seas may
linger longer offshore with the a more substantial improvement of
marine conditions after 9 PM tonight. High pressure to build over
the western Gulf by Monday morning with marine conditions vastly
improved for all of Monday.
Monday night through Saturday...deteriorating marine conditions
are expected Monday night through Tuesday night...with small craft
advisories likely to be needed towards the end of this period...as
an inverted surface trough develops over the western Gulf of Mexico
and steadily increases winds and builds seas along the Lower Texas
coast. Adverse wind and sea conditions will persist Wednesday into
Thursday night as the trough interacts with strong high pressure
building south into deep south Texas and the Rio Grande Valley.
The formation and quick exit of a weak low pressure area along the
Lower Texas coast Friday will actually improve marine conditions...
with a possible return to Small Craft Advisory conditions Saturday
due to the passage of a cold front.
Preliminary point temps/pops...
Bayview/Port Isabel 52 44 63 53 / 80 0 10 20
Brownsville 53 42 65 54 / 80 0 10 20
Harlingen 52 41 65 52 / 80 0 10 20
McAllen 53 41 66 54 / 50 0 0 20
Rio Grande City 56 41 65 50 / 30 0 0 20
South Padre Island 54 50 64 54 / 80 0 10 20
GM...Small Craft Advisory until 6 PM CST this evening for gmz130-132-
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