Scientific Forecaster Discussion
fxus65 kpub 221726
Area forecast discussion
National Weather Service Pueblo Colorado
1026 am MST Fri Nov 22 2019
Short term...(today and tonight)
issued at 350 am MST Fri Nov 22 2019
An occluding cyclone will be over the eastern plains at the
beginning of the short term forecast period (5am MST friday). The
response to the occluding cyclone's location will be longer lasting
snowfall over the eastern plains and eastern mountains, as compared
to the previous forecast package. The isentropic lift on the
backside of the low pressure center will create another round of
light snowfall starting over El Paso County and will travel south
over I-25 corridor throughout the morning and afternoon hours.
Expect snow to stop around 11am MST over El Paso County, followed by
Pueblo and Fremont counties by around 3pm, and Huerfano and Las
Animas counties by 7pm MST or so. The result will be an additional
inch of snow over the adjacent plains and lower amounts further
east. The eastern mountains are expected to see the higher amounts
of snow from the occluding cyclone, with an additional 3 to 5 inches
over the higher elevations throughout the day.
The prolonged snowfall and widespread cloud cover will keep high
temperatures well below average over the plains with values only
reaching the mid-30s. The upper Arkansas River valley and the San
Luis valley will be closer to seasonal, but still cool, with high
temperatures in the upper 30s to lower 40s.
The backside of this low pressure center will have significantly
lower precipitable water values. The lack of moisture will clear the skies
overnight and keep dew points very low, resulting in efficient
radiative cooling over the San Luis valley and the upper Rio
Grande River valley, and minimum temperature values in the single
digits. The upper Arkansas River valley and the eastern plains
will be in the lower to mid 20s. As the dry air aloft settles
over the region, there is the possibility for some fog over the
San Luis valley during the overnight hours. Forecast model
soundings show a very shallow layer of saturation up to 750hpa
with a distinct decoupled atmosphere above that layer, accompanied
with weak surface flow. Confidence is low right now, but the
possibility is there.
Long term...(saturday through thursday)
issued at 350 am MST Fri Nov 22 2019
Sat morning an upper disturbance will exit the area to the south and
for the rest of the day, there will be dry northerly flow aloft.
Temps will be warmer on Sat, especially over the eastern plains.
Highs will be in the 40s in the high valleys and in Teller County,
with lower and mid 50s across the plains.
Dry weather will continue through sun, although an upper level
disturbance will move south over the area on sun. Temps on sun will
likely be slightly warmer than on Sat.
Mon an upper level shortwave trof will approach the area from the
northwest, with some slight timing differences between forecast
models. It looks like by midday we could see some precip move
into the central mtns and maybe into the Pikes Peak region by
evening. The disturbance is forecast to move across the area Mon
night and into early Tue. The best dynamics and moisture with
this system is currently expected to be over the northern half of
co, and thus for our forecast area, the highest chances for precip
are expected over the sawatch and mosquito mtns and over Pikes
Peak, Teller County and the Palmer dvd. This system moves out of
the area by Tue afternoon, with drying conditions expected,
although there could be some lingering light showers over some of
Tue night and Wed and upper low and its associated trof are expected
to move over the West Coast. Ahead of this system, it appears that
precip will move into the mtn and high valleys of Colorado on Wed. The
upper low will be slow to move, but is expected to move south over
either northern or central California by Thu evening, with precip continuing
over the mtns and high valleys of co, especially along the
Aviation...(for the 18z tafs through 18z Saturday afternoon)
issued at 1019 am MST Fri Nov 22 2019
Upper low is gradually pulling east out of Colorado this morning.
Bands of snow along the I-25 corriodr and eastern plains are
expected to diminish through the aftn from west to east as the
upper system continues to move away.
Kcos and kpub: IFR to LIFR conditions through 22z this aftn due to
low clouds, fog and ongoing snow. Improving conditions between 22z
and 24z, then VFR conditions expected through the end of the
forecast period. West to northwest sfc winds at kpub and north to
northwest winds at kcos tonight should N IL any fog threat.
Kals: VFR conditions expected over the next 24 hrs.
Winter Weather Advisory until 11 am MST this morning for coz058-