Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Houston/Galveston Texas
835 PM CST sun Dec 21 2014

Update...
astronomical winter began at 5:03 PM CST today...and the first
night of the season looks to be a mild one. Surface analysis at 7
PM showed a developing Lee trough stretching from southwest Texas
north to the Front Range of the Rocky Mountains...with the region
on the western periphery of a surface ridge over the eastern
Continental U.S.. additionally...the cold front prognosticated to make its way into
southeast Texas late Monday into Tuesday morning was shown
stretching from near the Montana/North Dakota border southwest
towards the Rocky Mountains. Evening satellite imagery depicted
generally cloudy skies in place...with an area of clearing
stretching from near Brazoria County into Liberty County.

The surface ridge will continue to lose what little influence it
still has over the region overnight...allowing southeasterly to
southerly return flow to promote low-level moisture advection and
aid in redevelopment of the low cloud deck where clearing has been
observed. Latest hi-res guidance and forecast soundings indicate
enough saturation will be present late tonight into Monday morning
for the development of patchy drizzle. For the evening
update...have added mention of drizzle with the rest of the
forecast for tonight remaining largely on track.

Huffman

&&

Previous discussion... /issued 524 PM CST sun Dec 21 2014/

Discussion...
see 00z aviation discussion.

Aviation...
leaned heavily toward the more pessimistic hrrr/rap for the first
15 hours of the taf package. The GFS did not initialize well with
the NAM looking more like the hrrr. Feel IFR ceilings will develop
between 03-06z and then linger through 15z. After 15z surface winds
should begin to increase as the pressure gradient tightens and
veers to slightly SW-S. Am expecting enough mixing in the afternoon to
produce VFR conds. 43

Previous discussion... /issued 407 PM CST sun Dec 21 2014/

Discussion...
despite a few breaks in the cloud cover across southeast Texas...temperatures
have remained nearly steady in the middle to upper 50s with only a
few locations reaching the lower 60s. Not expecting much of a
diurnal variation in temperature overnight because forecast
soundings suggest cloud cover will fill back in. With a return to
onshore flow beginning late tonight into Monday...think the cloudy
skies will continue.

On Tuesday...a cold front will move through southeast Texas. The GFS and
European model (ecmwf) have sped up the timing of the frontal passage through the
area...with both models having the front through the central
portion of the County Warning Area by 12z. The NAM is slower with the movement of
the front through southeast Texas. Still uncertain on quantitative precipitation forecast coverage...as the
better jet dynamics and upper level support appear to be farther
east. Temperatures during the day on Tuesday will fall through the
40s and ending up in the 30s for many locations by Wednesday
morning. Have trended on the lower end of guidance due to the fact
that both the GFS and European model (ecmwf) show the 540 thickness line making it
to the coast by Wednesday at 12z.

Clear...cold...and dry conditions behind the front for Wednesday
and Thursday will occur before the passage of the next cold front
sometime Friday afternoon. The GFS and European model (ecmwf) disagree on the
timing...with the European model (ecmwf) being the more aggressive of the two
models in bringing it through southeast Texas. 13

Marine...

As the surface high continues to move off to the east low level winds to
continue shifting to the east then southeast tonight through early Monday morning-
ing. Tightening pressure gradient (in response to the next weather system
deepening over the central plains) will help to increase wind speeds
Monday...but not anticipating any flags/advisories for this time frame.
However this is expected to change by Tuesday evening with the passage of a
strong cold front (tues aftn). Gale force wind gusts possible in the
wake of the front so small craft advisories likely. 41

&&

Preliminary point temps/pops...
College Station (cll) 51 71 52 54 36 / 10 10 10 20 10
Houston (iah) 53 73 57 58 39 / 10 10 20 40 10
Galveston (gls) 56 72 62 62 45 / 10 10 20 40 10

&&

Hgx watches/warnings/advisories...
Texas...none.
GM...none.
&&

$$

National Weather Service Glossary of Abbreviations