Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/19/18
Area Forecast Discussion
National Weather Service Fort Worth TX
837 PM CST Thu Jan 18 2018
Made a few adjustments to the ongoing forecast to account for
observed trends in cloud cover and temperatures. Satellite data
shows a few areas of cloud cover. The first is the cloud deck
which was over much of the area around 00Z. This cloud deck is
advecting eastward for the most part. This will enable much of
the region tonight to see mostly clear or partly cloudy skies for
the majority of the night. The second area is a deck of high
cloud cover, streaming in from the northwest.
The third area observed on satellite and radar, is a disturbance
moving through the upper level trough. This disturbance is located
near Austin at 02Z, and will continue to move slowly northeast
and east overnight. A few observation sites in Central Texas have
reported brief light rain, so a few light showers are possible
across our far southern areas, especially Bell, Milam, Robertson
and Leon Counties. However, the extremely dry air at the surface
will likely keep widespread rain from ever reaching the ground.
Have therefore kept out the mention of rain in the forecast
update, yet it does remain a low possibility.
.AVIATION... /Issued 529 PM CST Thu Jan 18 2018/
A VFR cloud deck remains in place over all TAF sites
this evening, but will move east of DFW Metroplex sites in the
next couple of hours. Meanwhile, a swath of MVFR stratus continues
to surge northward through the Texas Hill Country which will
pivot northeastward overnight. This may result in a couple hours
of MVFR cigs at Waco around daybreak, but expect most cigs to
remain VFR around 3-4 kft. Otherwise, south winds will be on the
increase at 10-20 kts throughout much of Friday. Towards the end
of the TAF period (late Friday afternoon or evening), cigs around
2-3 kft should begin overspreading all TAF sites; MVFR conditions
are likely thereafter.
.SHORT TERM... /Issued 347 PM CST Thu Jan 18 2018/
/Tonight through sunrise Friday/
Main weather concern during the short term time period will be
the areal coverage of cloud cover and its impact on overnight low
temperatures. Otherwise, tranquil conditions are anticipated.
Satellite and surface observations this afternoon indicate that
the initial surge of shallow, low level moisture continues to
stream northward. This moisture appears to be centered around
850-925mb as evidenced in RAP soundings across the area. Flow
within and just below this layer will increase this evening and
into the overnight hours in response to pressure/height falls
across the upper midwest. The increase in low level flow coupled
with an increase in low level moisture should lead to "warmer"
overnight conditions with most areas falling into the 20s and 30s
areawide. A few of the sheltered/low lying areas may fall into the
upper teens, however. The low level flow will also help to
transport additional moisture and stratus northward. While there
is some uncertainty in the northern extent of the cloud shield, it
looks like a guarantee for mostly cloudy skies down across
eastern and southeastern zones. As a result, I`ve kept
temperatures a little higher across this part of the FA with
readings near or just above freezing. The breezy conditions just
above the surface should mitigate any potential for fog, but if
moisture deepens enough, there may be a few sprinkles or drizzle.
For now, this threat is too low to include in the forecast.
.LONG TERM... /Issued 347 PM CST Thu Jan 18 2018/
/Friday through Thursday/
Friday morning will start out considerably warmer than the
previous few mornings with most areas near freezing, but southerly
winds well established. Cloud cover that has spread over the
region this afternoon will thin some overnight, although thicker
low cloud cover associated with a slug of deeper moisture will
spread north overnight primarily affecting the southeast counties.
This is likely to persist through the day Friday and will hamper
a more significant warmup across the eastern and southern parts of
the CWA. Highs on Friday are likely to remain in the upper 40s
and lower 50s across the southeast tomorrow while areas farther
north and west warm into the lower 60s. The increase in moisture
atop some already cool air in place will likely result in some
areas of light rain or drizzle late Friday night into Saturday
morning, especially east of I-35.
By Saturday, a strong upper trough will dig into the southwest
U.S. resulting in surface pressure falls across much of the
Central Plains. Southerly winds will increase in response and
continue to transport moisture northward. A few areas of light
rain or showers may develop mainly east of I-35 where we`ll have
20% PoPs. Strong southwest winds above the surface will aide in
warming with highs expected to climb into the 60s and lower 70s.
The extensive low clouds will also be accompanied by very low rain
chances overnight Saturday night.
By Sunday, as the upper trough ejects into the Central Plains, a
Pacific front/dryline will advance eastward into North Texas. Low
level flow will veer rather quickly during the late morning hours.
Despite strong forcing for ascent spreading across the region, the
veering flow and relatively weak lapse rates will result in little
instability across North Texas. Showers and a few thunderstorms
may develop by midday into early afternoon mainly east of I-35.
We`ll have PoPs at 50-70% for areas mainly east of I-35 Sunday
afternoon. The lack of instability and quickly veering flow should
result in a relatively low severe weather threat. Any
precipitation should quickly end from west to east Sunday evening.
After the passage of the front, we should enter a period of
relatively quiet weather next week with high pressure settling in
through mid week and temperatures just slightly above normal.
We`ll be watching another strong upper trough dig into the western
U.S. toward the end of next week which could bring additional rain
chances to the region.
.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth 32 57 47 68 55 / 0 0 10 5 20
Waco 29 54 45 70 55 / 0 0 20 10 20
Paris 26 53 43 65 54 / 0 0 20 20 20
Denton 27 59 46 69 54 / 0 0 5 5 10
McKinney 25 55 45 68 54 / 0 0 20 10 20
Dallas 32 57 49 68 56 / 0 0 20 10 20
Terrell 28 53 47 68 54 / 0 0 20 20 20
Corsicana 28 51 48 68 55 / 0 0 20 20 20
Temple 29 52 46 70 54 / 10 5 20 10 20
Mineral Wells 27 63 43 72 51 / 0 0 0 5 5
Area Forecast Discussion
National Weather Service San Angelo TX
921 PM CST Thu Jan 18 2018
Updated for stratus and slightly warmer overnight lows, along and
east of a San Angelo to Sonora line. Short range models bring
stratus northwest overnight affecting areas as far west and
northwest as Sonora and San Angelo by morning. Low level moisture
is very shallow, however, and clouds should break up quickly mid
.PREV DISCUSSION... /issued 551 PM CST Thu Jan 18 2018/
Short range models including the GLAMP25 and HRRR seem to have
the best handle current placement of low level moisture and
clouds, advecting them northward back Sonora, Junction, and San
Angelo after midnight, with clearing midmorning. Kept KJCT in
MVFR ceilings overnight, although models suggests ceilings may
temporarily rise above 3000 FT later this evening, before falling
back to MVFR after midnight. Otherwise south winds may gust over
20 KTS at KABI and KSJT by noon Friday as lee trough develops.
PREV DISCUSSION... /issued 242 PM CST Thu Jan 18 2018/
(Friday Night through next Thursday)
The main weather concern is with the heightened fire weather
potential for Sunday. Weak upper ridging over Texas Friday night
will be followed by southwest flow aloft Saturday and Saturday
night, as a strong upper trough moves east across the western CONUS
and into the Rockies. With an increase in south winds, lows Friday
night will not be as cold (in the 35-40 degree range). With lee
surface trough to our west and increased surface pressure gradient,
breezy south-southwest winds are expected Saturday and Saturday
night. Temperatures will be well-above normal Saturday with highs in
the 70-75 degree range across most of our area, with upper 60s/near
70 along the I-10 corridor where some morning low cloud cover is
With the aforementioned upper trough, a closed low is progged to
develop, and move from the Colorado/New Mexico border northeast into
Kansas on Sunday. Marginally sufficient moisture return will support
a slight chance of showers across the area east of a Brownwood to
Junction line Sunday morning, with the approach of a Pacific
front/dryline. The Pacific front/dryline will advance east of our
area by midday or early Sunday afternoon, ending any rain chances.
Increased and gusty west winds will follow its passage and continue
through late Sunday afternoon. The combination of these winds with
above normal temperatures (in the mid/upper 60s for much of our
area), and an intrusion of very dry air is expected to result in
elevated to critical fire weather conditions. The main area of
concern will be across the area along/north of a Sterling City to
Brownwood line, in the Noon to 6 PM time frame on Sunday. We will
continue to monitor, as model changes in the track, timing and
strength of this system will affect where the heightened fire
weather potential will be.
Temperatures will be a little cooler and closer to normal on Monday.
The forecast looks dry Tuesday into Thursday of next week across our
area. Lows are expected to be in the upper 20s to lower 30s Tuesday,
mostly in the lower 30s Wednesday, and in the mid to upper 30s
Thursday. Highs are expected to be generally in the 60-65 degree
range across much of our area during that time.
.PRELIMINARY POINT TEMPS/POPS...
Abilene 31 62 40 73 / 0 0 0 0
San Angelo 30 62 37 75 / 0 0 0 0
Junction 35 59 38 72 / 0 0 0 0
Brownwood 31 62 40 73 / 0 0 0 0
Sweetwater 28 63 39 74 / 0 0 0 0
Ozona 29 57 35 70 / 0 0 0 0