Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion...updated 
National Weather Service Brownsville Texas
541 am CST Friday Nov 27 2015

Discussion...updated for latest aviation discussion below.


Aviation...extensive overcast skies through the day and overnight
as a surge of moisture invades the region from a eastern Pacific
hurricane. The atmosphere from the surface to well above 10000
feet remain nearly saturated and will produce multi-layered
clouds. Prevailing MVFR ceilings are the mostly likely broken to overcast
conditions with some tempo IFR at times this morning and VFR this
afternoon. A few showers may increase in coverage as the day
progresses as the moisture from the Pacific tropical cylcone
continues to stream over south texa. Southeast surface winds to
increase by afternoon as gradient strengthens in advance of a cold
front that is enter central Texas.


Previous discussion... /issued 346 am CST Friday Nov 27 2015/

Short term /now through Saturday/...the forecast remains virtually
the same as yesterday but there continues to be a lot of uncertainty.
Challenges remains amount of and placement of precipitation and the
speed/progress of the cold front over central Texas expected to slow
down as it moves into south Texas tonight and Saturday.

Deep south Texas remains under a deep southwest tropical flow
between a quasi-stationary upper low over the intermountain west and
expansive upper ridge over the Gulf of Mexico. Deep tropical
moisture is in place with forecast precipitable waters exceeding 2 inches by 12z
this morning and showing a continue climb nearing 2.15 inches or
close if not over 3 Standard deviations above normal. The anomalous
moisture content is due to the plume of moisture from east Pacific
Hurricane Sandra which is forecast to weaken before a Mexican
landfall but remnant moisture will continue to flow over Texas
through the forecast period. Even with all the moisture lifting of
the moisture remains limited with our region under the influence of
the upper ridge centered over the Gulf. West areas to see slightly
better chances with the slightly better moisture content. Inherited
forecast and latest guidance continue to indicate scattered showers
with an isolated shot of a clap of thunder. Temperatures to do not
have much to climb with overnight lows not falling to much with the
clouds cover and subtle southeast surface flow. Temperatures to run
into the low to middle 80s even with the dense overcast.

Models continue their timing differences with a cold front moving
into north central Texas. The front is expected to slow down
considerable as it moves into south Texas Saturday. Just the pure
density of the cold air could be enough to push the front off the
lower coast by Sunday morning but this continues to look like a
struggle. The latest forecast pushes the front into the northwest
counties Saturday afternoon with possible a Big Range of
temperatures from Zapata and Hebbronville to Brownsville. The other
uncertainty is the rain chances. The front should act as a decent
forcing mechanism and the rain chances do go up. However the
precipitation amounts remain rather low and weather prediction
center keeps the quantitative precipitation forecast near zero for Saturday which is difficult to
grasp with all the moisture and front. Any subtle disturbance within
the southwest flow could tip the bucket to a much more dynamic
rainfall event in deep south Texas. Will continue to monitor.

Coastal flooding...little change in the onshore flow and the high
swell conditions across the Lower Texas coast. Will continue to play
up the tidal overwash with tides still around 1 foot above normal
and the next high tide at 630ish this evening. Have extended the
coastal flood statement and will refer the decision off an upgrade to
an advisory for the day crew once the sun rises and they can monitor
the beach cams.

Long term /Saturday night through Thursday/...the intrusion of a
weak cold front into deep south Texas and the Rio Grande Valley
during the weekend...and the passage of a much more robust cold
front Wednesday through Wednesday night...continue to the best
opportunities for precipitation during the long term portion of
the forecast...with scattered showers forecast for these time
periods. Not much cold air exists with the weekend front...and it
is expected that temperatures will prevail at near normal levels
at that time and into early in the week. The middle-week cold front
is a bit chillier and will help to knock temperatures at well
below normal levels in its wake. through Saturday...a persistent east-southeast flow over the
entire Gulf continues to drive a long period swell towards the
Lower Texas coast. Model projections show little change of these
conditions over the next 24 hours. The moderate winds and higher
swells warrant an extension of the small craft advisories for the
Gulf waters through at least Saturday morning. A cold front
working its way through central Texas is expected to slow down
considerably Saturday and have a difficult time working its way
offshore. Winds will diminish slightly but swell/sea conditions
will be much slower to subside.

Saturday night through Thursday...generally moderate winds and
seas are forecast along the Lower Texas coast Saturday night
through Wednesday as a weak cold front intrudes into deep south
Texas and the Rio Grande Valley during the weekend. Stronger winds
and higher seas are likely Wednesday night through Thursday...with
small craft advisories a more potent cold front
moves from north to south through the Lower Texas coastal waters.


Bro watches/warnings/advisories...
GM...Small Craft Advisory until noon CST Saturday for gmz150-155-170-



This product is also available on the web at:


National Weather Service Glossary of Abbreviations