Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Houston/Galveston Texas
345 PM CDT sun Mar 9 2014
another typical winter 2013-14 day under overcast...cool and damp.
With the 850 mb front washing out near the coast this afternoon...late
day breaks in this cloud cover may actually allow some communities
(closer to the shoreline) to experience the 60s for a brief hour
or two before the sun sets at 730 lt. As many head into their
first few days of Spring break week...weather changes are underway.
The main weather driver will be the large near-stationary upper
low that is churning between the sonara/Chihuahua provinces in
northern Mexico. This low/open wave inverted trough will move east
and be into lower Rio Grande Valley by this time tomorrow. Higher
positive vorticity advection being thrown up ahead of this feature...along with a slight
split in the upper jet structure...may be the impetus to commence
west-southwestern (coastal Bend/Matagorda bay) rain as early as
middle-late Monday afternoon. Of course...the east-northeast movement
and any subsequent shortwave disturbance riding around its eastern
periphery will determine the amount and location of rainfall...but
all indicators are that many over the southern third of the County Warning Area
will pick up on average half inch to an inch through Tuesday morning.
Highest rainfall from episodes of more moderate rain and thunderstorm
activity will be primarily be confined to the offshore waters...or
east of either a weak closed-off low or an inverted trough axis. Probability of precipitation/wx/qpf
currently reflecting a scenario of the low continuing on more of
an eastern-versus-northern trek into the northwestern Gulf by sunrise
Warmth is on the way as early day overcast breaks up through the
day tomorrow...with the exception being closer to the coast...and
thermometers warm into the seasonable lower 70s. The trough axis
will be over Louisiana by Tuesday afternoon and backside subsidence
should clear skies out to partly cloudy to mostly sunny and allow
our local Star to work on US. There may be enough work done by
middle-day Tuesday to realize near 80 f maximum temperature readings.
A strong cold frontal passage Wednesday will be dry rain-wise but
following cold air advection should be enough (near 5 c 800 mb temps) to regulate
warmth into the lower 60s under a moderate north wind. If these
north-NE winds die down enough early Thursday morning...far interior
readings will again chill back down to slightly under 40f (mid-
upper 40s along coast). Thus...after a few days of Spring the
region will fall back to more mild winter standards to close out
the work week. Return flow by late Thursday will increase lower
level moisture values and increase those under-the-cap showers
Friday. West-Central Plains upper troughing developing further
south and southwest...with lowering western Texas surface pressures Saturday
..may allow higher middle-upper vorticity to stream into an increasing
unstable environment ahead of a Sunday frontal passage. Low end chance probability of precipitation
next weekend to account for this situation. 31
a weak coastal trough will maintain a north-northeast wind tonight. As high
pressure drifts east on Monday...winds will veer to the southeast
by afternoon. The gradient will begin to relax tonight but feel
its best to maintain the scec for the offshore waters through 05z.
A weak area of low pressure will move east of the area on Tuesday
and west winds on the back side of this feature will develop over
the coastal waters. A strong cold front will move offshore Wednesday
morning with advisory conditions likely in its wake. Onshore winds
will redevelop next Thursday and persist through next Sunday morning.
Preliminary point temps/pops...
College Station (cll) 45 73 54 77 49 / 10 30 30 10 10
Houston (iah) 48 72 54 75 53 / 10 30 50 30 10
Galveston (gls) 53 69 57 70 57 / 10 30 60 30 10
GM...small craft should exercise caution until 11 PM CDT this evening
for the following zones: waters from Freeport to the
Matagorda Ship Channel 20 nm to 60 nm...waters from
Freeport to the Matagorda Ship Channel out 20 nm...waters
from High Island to Freeport 20 to 60 nm.