Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Houston/Galveston Texas
528 PM CST Wednesday Dec 24 2014
see the 00z aviation discussion below.
high pressure over far southern Texas and northern Mexico will
move into the western and northern Gulf of Mexico tonight and
Thursday. By late Thursday morning...the pressure gradient will
tighten enough for breezy southerly winds to develop over all the
inland sites. The winds may gust to between 20 and 25 knots
during the afternoon. Otherwise...VFR conditions are expected.
Previous discussion... /issued 307 PM CST Wednesday Dec 24 2014/
a rather cool afternoon with maximum temperatures struggling to warm into the
upper 50s. Cloud cover over the eastern half of the area will exit
the region by sunset leaving clear skies overnight. Winds will
also decouple as surface high pressure over northern Mexico drifts
east. The high will be east of the region on Thursday and winds
will become onshore and strengthen as low pressure over southeast
Colorado deepens. Moisture levels will deepen on Friday as onshore
winds persist. Precipitable water values on Friday reach 1.10 and forecast soundings
saturate to around 800 mb. Moisture looks deep enough to generate
a few showers by Friday afternoon. Precipitable water values reach 1.40 inches on Saturday
ahead of another cold front. The front will trigger scattered
showers and thunderstorms as it crosses the area. Post frontal
rain will likely persist Sat night into early Sunday as the flow
aloft remains out of the southwest and surface winds will be north.
Isentropic upglide should be maximized Sat night. A shortwave trough
will approach the Pacific coast on Saturday night and this
feature will nudge another shortwave over SW Texas eastward. The Texas
shortwave fills as it moves east and the flow aloft becomes zonal by
Monday 00z. The set up for isentropic upglide on Sunday which looked
extremely favorable 24 hours ago looks considerably less favorable
now. The Canadian continues to show some potential for isentropic
upglide while the GFS and European model (ecmwf) have backed off. Global models
continue to show southeast Texas in a potent 155 knots rrq which should enhance
precipitation through early Sun afternoon. Subsidence in the wake of the
departing shortwave should allow for a brief period of dry weather and
clearing skies on Monday. Another upper trough will develop over
the SW U.S. And isentropic upglide develops again on Tuesday with
clouds and light rain returning. The European model (ecmwf) is bringing very cold
air into Texas around the new years Holiday and forecast soundings do
show some potential for sleet/freeze rain north of a Bryan to
exercise caution statement will remain necessary into the early
evening with winds...although winds will diminish through the
evening before turning to onshore flow Christmas morning.
Southerly winds will likely reach cautionary or even approach Small Craft Advisory
criteria by Thursday night tomorrow...especially for the outer
waters. Another cold front will cross the area late Saturday
bringing a return of unsettled weather for the weekend.
Tides are currently about 1 foot below normal in the upper bays.
However...as we move out of low tide and winds diminish later today
expect any low tide issues to abate by early this evening.
Preliminary point temps/pops...
College Station (cll) 35 61 49 69 59 / 0 0 10 20 40
Houston (iah) 36 62 54 71 61 / 0 0 10 20 40
Galveston (gls) 48 62 62 69 63 / 0 0 10 20 30