Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Brownsville Texas
1139 am CST Tuesday Dec 10 2013
Discussion...updated for latest aviation discussion below.
Aviation...satellite images and surface observations indicate low
to middle level clouds across the eastern and southern portions of
the County Warning Area late this morning with middle to high level clouds across the
northern and western portions. Ceilings were near 1700 at kspl to
near 8000ft at kbks. Expect MVFR conditions to continue across
the coastal sections of deep south Texas and spread inland tonight
as 850mb winds veer from the east to southeast allowing moisture
aloft to move across the shallow colder air at the surface.
Previous discussion... /issued 940 am CST Tuesday Dec 10 2013/
discussion...updated for latest marine discussion below.
Marine...seas were near 11 feet with north winds near 22 knots
with gusts to near 30 knots at buoy020 this morning. Strong north
to northeast winds will prevail across the coastal waters the rest
of the morning into the afternoon as the pressure gradient remains
strong across the western Gulf of Mexico today. Have allowed Gale
Warning to expire and small craft advisories are now in effect for
the Lower Texas coastal waters. Winds will diminish tonight but
seas will remain high offshore the Lower Texas coast.
Previous discussion... /issued 522 am CST Tuesday Dec 10 2013/
discussion...updated for latest aviation discussion below.
Aviation...MVFR is a few hours away from making it to valley
airports as drier air is working in courtesy of high pressure in
northern Texas and weakening isentropic lift. Drizzle and light
rain will continue through middle morning but will dissipate and move
offshore as the morning progresses. MVFR will return after middle
morning with VFR conds likely this afternoon with a cloud deck
around 6k feet. Guidance differs on MVFR ceilings after 00z and will
take worst case and bring back in MVFR ceilings at the end of the taf.
Strong winds will continue today with gusts to 25 knots possible.
Winds will decrease to under 10 knots by sunset.
Previous discussion... /issued 334 am CST Tuesday Dec 10 2013/
Short term /now through Wednesday/...fresh surge from a 1033 mb
high pressure is working into the region currently...with cold air
advection across much of the area and winds becoming gusty across
most of the area and some gusts approaching 25 miles per hour. Temperatures
to our north in Duval...Jim Wells...and Kleberg counties are
decreasing into the upper 30s with wind chills in the lower 30s.
With a few more hours of cooling and winds expected to slightly
increase...will keep Wind Chill Advisory as is /runs 3 am to 9 am
across all of deep south Texas/.
Light rain and drizzle continues across the lower and Middle Valley
and adjacent ranch lands areas. As the surge continues southward...it
is expected to help push the stationary boundary to our south
further south and isentropic upglide will weaken significantly.
Inherited probability of precipitation looked good...slight chance probability of precipitation were kept in the
middle and Lower Valley and this area will shift to the coastal
waters later today. Isentropic upglide doesn/T end completely...
upglide gets going again Tuesday night and Wednesday with chance
probability of precipitation being introduced in the coastal waters with slight chance
mainly east of Highway 281.
Drier air works into the northern and western sections of our area
and should see more sun in that area than points east. However...
strength of cold air advection will keep highs today in the upper
40s and lower 50s area wide. Clouds in the Lower Valley and east
of Highway 281 will keep lows tonight in the upper 30s to lower 40s.
In the ranch lands...radiational cooling will drop temperatures to
the middle 30s. Met/mav guidance reveals lows tomorrow night will
stay above freezing and winds will be relatively light so no
freeze warning or wind chill advisories expected. Moisture
increases on Wednesday /especially east of 77 and in the valley/
so highs on Wednesday will be warmer /3-5 degrees in the ranch
lands with 6-10 degrees in the valley/.
Long term /Wednesday night through Sunday night/...broad middle level
troughing will preside over the eastern United States Wednesday
night...above 1039 mb high pressure over the middle Mississippi Valley
and a cut off low over Southern California/baja. The same high
pressure will extend back over east and central Texas...with cooler
air filtering south capped under southwest flow aloft...leading to
overcast skies and stabilizing temperatures for the day. Lows will be near
normal but high temperatures Thursday will be cooler than normal by about
10 degrees as cooler high pressure filters over the area and coastal
troughing produces light showers along the coast. Thursday night
will be slightly warmer but Friday should be the turning point as
winds shift to southeast and capping strengthens due to the approach
of the ejecting upstream cut off low heading east into West Texas...
with a 1006 mb surface low over the Panhandle...supporting an influx
of moisture to East Texas but a bit too far north of the lower Rio
Grande Valley. Temperatures Friday should warm into the lower 70s Lower
Valley and the lower 60s across the ranch lands...and near normal
overall. Friday night as well should even be warmer than normal with
the friendly return of southeast winds.
Look for a front to arrive Saturday morning however...as the middle
level trough exits over East Texas and lower latitude drier air is
pulled around the backside of exiting lower pressure and downstream
of ridging building over the West Coast. Skies will clear through
the day Saturday...with light northwest winds becoming moderate
north. High temperatures will be pleasant in the 60s and 70s. Any
lingering rain chances over the Gulf will get swept offshore through
the day. Temperatures Saturday night will cool back down to normal under
mostly clear skies...with a cooler...but pleasant and sunny Sunday.
now through Wednesday...much anticipated surge of high pressure
is working into the Lower Texas coastal waters with current observation at
kmzg and kbbf showing gale force gusts at 08z/2am. Gale Warning in
effect across the Lower Texas coastal waters through 15z/9am looks
good based on gale force gusts working into our waters from the
north. After 15z/9am...small craft advisories are in effect as
strong winds and high seas continue through Tuesday and Tuesday
night. Wednesday morning and early afternoon appear better for
marine activity but winds begin to increase later Wednesday
Wednesday night through Friday night...1039 mb high pressure will
shift south from the middle Mississippi Valley toward the north Gulf
Coast Wednesday night...bolstering light to moderate northeast
winds toward 20 knots and Small Craft Advisory criteria. Coastal
troughing will keep light precipitation in the picture. Small
Craft Advisory conditions will be probable late Wednesday night
through Thursday when the high pressure slides east and the
gradient weakens. MDT northeast winds will veer to southeast
Thursday night with seas maintaining moderate heights along the
way. Lower pressure upstream over the Texas Panhandle will tighten
the gradient enough for at least exercise caution conditions over
the Gulf waters Friday. Low pressure will fill and shift east as
the next cold front approaches from the northwest Friday night.
Light rain will continue as long as winds remain northeast...then
tending to end Thursday night into Friday.
GM...Small Craft Advisory for winds until 3 PM CST this afternoon for
Small Craft Advisory until midnight CST tonight for gmz150-155-
This product is also available on the web at: