Scientific Forecaster Discussion
fxus64 ksjt 082051
Area forecast discussion
National Weather Service San Angelo Texas
251 PM CST sun Dec 8 2019
(tonight and monday)
Zonal flow aloft continues across west central Texas this afternoon,
with water vapor satellite imagery showing upper level moisture
streaming in from the west, which is resulting in scattered to
broken high clouds moving over the region. At the surface, high
pressure to the east and strengthening low pressure over southeast
Colorado is resulting in a decently strong pressure gradient, causing
gusty southwesterly winds of 15 mph with gusts of 20-25 mph.
Temperatures as of 1 PM are roughly 7-13 degrees higher than at this
time yesterday, due to the increase in warm southwesterly flow.
Zonal flow aloft will continue tonight then become southwesterly
Monday as a potent short-wave trough approaches from the west.
Increasing cloud cover and a continued increase in dewpoints will
result in a warmer night tonight, with lows in the low to mid 50s.
Monday, expect mostly cloudy skies with highs in the mid to upper
70s south of the Big Country. Meanwhile, cooler conditions expected
in the Big Country (highs mainly in the low to mid 60s) where a cold
front will be moving through that region by late afternoon.
Increasing lift with the approaching trough in the afternoon will
combine with increasingly deep moisture to bring chances for showers
by late afternoon along and west of an Ozona to Cross Plains line.
(monday night through this weekend)
The aforementioned trough and cold front will push its way into
west central Texas on Monday night through Tuesday. Plenty of lift
is available with the right-rear quadrant of a jet streak
located right over the region. Models are in good agreement of
the axis of the heaviest rain being located roughly from The Big
Bend area to the metroplex. Went with likely to definite precip
chances for this time period as a result. The Fly in the ointment,
however, is just how far south the sub-freezing air advances. At
this point, model soundings are showing a weak (0-1 deg c) warm
nose at 850mb above the subfreezing layer for much of the Big
Country late Monday night. So, we have introduced chances for
snow and sleet between 3am and 9am Tuesday morning. Regardless,
this system should exit the area rapidly by late Tuesday morning,
so anything that develops will be at the tail-end of the event. It
is likely that the ground temperatures will be above freezing and
wet, so any accumulation will be light, and only around a tenth
of an inch in higher-elevation spots where surfaces may be below
freezing. For now, this is below criteria for a Winter Weather
Advisory, so we will defer to the evening and midnight shifts for
For midweek, the forecast looks much quieter. High temperatures on
Tuesday will remain cool due to cloud cover and wet ground, but
should start to recover on Wednesday, with 60s continuing for the
rest of the week. Models are starting to show another front
moving into the Southern Plains on Sunday night into Monday, but
early indications are that this system will be dry.
Preliminary point temps/pops...
Abilene 76 56 65 33 / 0 0 20 90
San Angelo 78 54 73 37 / 0 0 20 100
Junction 76 52 80 41 / 0 0 0 90
Brownwood 77 53 75 35 / 0 0 5 100
Sweetwater 75 54 61 31 / 0 0 30 90
Ozona 73 51 73 39 / 0 0 10 100