Area Forecast Discussion
Issued by NWS San Angelo, TX
FXUS64 KSJT 091154 AAA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN ANGELO TX
554 AM CST MON DEC 9 2013
To expand the Freezing Fog Advisory...
Areas of freezing fog across the Big Country, Heartland and
Northwest Hill country continue to expand to the south and west.
Temperatures are below freezing across the entire area and given
the expansion of the fog, I went ahead and expanded the advisory
to include all of the Big Country and the northern Concho Valley.
The freezing fog could approach areas farther south in the next
few hours, including San Angelo, so I will continue to monitor
trends and these counties may need to eventually be added.
Otherwise, the rest of the forecast looks on track.
Please see the aviation discussion below...
Stratus/fog continues to expand through much of West Central Texas
this morning resulting in IFR to LIFR conditions. KSOA is a bit
more tricky, as the stratus to the south is struggling to expand
northward. For now, I have indicated MVFR ceilings by 14z, and
will continue to monitor. Some improvement in ceilings is forecast
by late morning or early afternoon, with MVFR ceilings returning
to most sites. Winds today will be from the north at 5 to 10 knots
.PREV DISCUSSION... /ISSUED 356 AM CST MON DEC 9 2013/
Today and Tonight
A cold front is currently moving through the Big Country and
should be approaching the Interstate 10 corridor shortly after
sunrise. Winds behind the front will become north and increase to
about 8 to 12 mph, with colder air slowly filtering into West
Central Texas. In addition, areas of freezing fog are evident just
to the east of our area, which has slowly been creeping west. I
expect this freezing fog to expand to a Throckmorton, to Coleman,
to Mason line in the next few hours. A freezing fog advisory is in
effect for parts of the Heartland through 9 AM, and I will
continue to monitor trends for the possibility of expanding it
north into parts of the Big Country and south toward Mason county.
The HRRR is also indicating some post frontal fog across parts of
the Big Country, which will need to be monitored. Stratus should
fill in this morning behind the front, with much of the area
becoming overcast by mid morning. Given the expected cloud cover
and cold air advection, I lowered high temperatures slightly.
Highs will range from the upper 20s north of Interstate 20, to the
mid 40s across the Interstate 10 corridor.
Cloudy skies through much of the overnight period will not
support ideal radiational cooling conditions, but given the cold
airmass that will be filtering into the region, I went ahead and
lowered low temperatures slightly. Tuesday morning low
temperatures will generally be in the teens to lower 20s across
all of West Central Texas.
Tuesday through Sunday
As a fast moving shortwave trough moves through the Great Lakes
region Tuesday night into Wednesday, a cold front will move into
Texas, causing another brief cooling for Wednesday into Thursday.
However, no precipitation is expected with the front. Lee
troughing on Thursday will allow winds to quickly turn back to the
south in our area, allowing temperatures to warm back up across
the area Thursday and especially Friday. An upper level low
initially off the coast of California on Monday will move across
the Desert Southwest and into the Texas panhandle by Friday. As
this low approaches, weak shortwaves will move across the area out
ahead of it, interacting with moisture return and low level warm
air advection, resulting in at least a slight chance for showers
mainly Thursday afternoon and Thursday night, with some lingering
showers moving out of the area on Friday.
The upper level low will then move east towards the Mississippi
Valley by Saturday, sending a cold front into the area. And while
the cold front will slow the warming trend, the air mass behind
the front will not be of arctic origin, so while we have gone
cooler than the MOS guidance for Saturday and Sunday, temperatures
should continue to trend closer to normal values through the
.PRELIMINARY POINT TEMPS/POPS...
Abilene 18 39 27 42 24 / 5 0 0 0 5
San Angelo 19 44 26 46 26 / 5 0 0 0 5
Junction 22 47 24 52 29 / 10 5 0 0 10
FREEZING FOG ADVISORY until 10 AM CST this morning FOR THE
FOLLOWING ZONES: Brown...Callahan...Coke...Coleman...Fisher...