Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus65 kpub 132152 
afdpub

Area forecast discussion
National Weather Service Pueblo Colorado
252 PM MST Fri Dec 13 2019

Short term...(this evening through saturday)
issued at 251 PM MST Fri Dec 13 2019

Primary near/short range meteorological focus is on the amount of
additional snow over primarily Continental Divide locations from
tonight into Saturday afternoon, with additional issues over the County Warning Area
being winds and temperatures.

County Warning Area currently experiencing snow over Continental Divide locations
such at Leadville, Wolf Creek Pass and Monarch Pass in addition to
gusty winds, with recent winds during the previous few hours
gusting to around 50 mph at locations such as Walsenburg, Bear
Creek, Salida, Aguilar, Weston and Colorado Springs. In addition,
areas east of the Continental Divide are also generally experiencing
above seasonal mid-December temperatures in combination with dry
conditions.

Recent pv analysis, real-time data, computer simulations and
forecast model soundings suggest that snow, heavy at times will
continue over Continental Divide locations, especially from later
tonight into Saturday and have issued a Winter Storm Warning for the
eastern San Juan Mountains beginning at 11 PM tonight.

Also, have maintained the Winter Storm Warning for portions of the
central mountains during the balance of the longer term. At this
time, project that an additional 8 inches or more of snow should be
observed over the Winter Storm Warning locations from tonight into
Saturday afternoon.

Elsewhere, locations east of the Continental Divide should be graced
by basically low-grade to nil pops in combination with above
seasonal temperatures and gusty winds at times during the next 24
hours.



Long term...(saturday night through friday)
issued at 251 PM MST Fri Dec 13 2019

Saturday night through Sunday night...the last in a series of
disturbances will move across the state. Saturday evening, the
models and ensembles are consistent with the flow turning more
southwesterly over the eastern San Juan and La Garita Mountains.
Upgraded the watch for the eastern San Juans to a warning, which
will just continue the warning already in effect. The La Garita
Mountains will have less precipitation from this event. Amounts
are more the high end of an advisory, but for simplicity also
upgraded the la garitas to a warning. Gusty winds will also result
in some blowing and drifting snow. After the trough passes late
Sunday afternoon, flow aloft will become northwesterly which will
favor the mountains of lake and Chaffee counties. Given the
prolonged event, totals up to 2 feet are possible in parts of the
warning areas.

Further east, next challenge is the southeast mountains and Interstate
25 corridor Sunday into early Monday. Latest GFS trended drier
while the ec trended wetter. Collaborated with wpc concerning the
event as they can view many more models and ensemble members. Wpc
stated that there is no trend in the consensus. Used a blend of
nbm and wpc quantitative precipitation forecast grids and slightly decreased snow ratios. Storm
totals are similar to the previous forecasts. Open waves moving
across the region are tricky forecasts as last minute trends can
lead to less or more snowfall. Models have a band of upglide over
the eastern plains with a prolonged period of light snow. Current
ec and GFS have the band centered along the Arkansas River, but
this band can move north or south. Given the significant chances
for snow but with a fair amount of uncertainty, decided to leave
the watch up for the eastern mountains and i25 corridor. Question
for the eastern mountains will more likely be an advisory versus a
warning while impacts are more uncertain further east.

Monday and Tuesday...trough moves to the east with some
lingering light snow Monday morning over the mountains. Air aloft
will be quite chilly. Main weather story will be the cold
temperatures Monday and Tuesday. Monday night will have lows of
the single digits on the plains. With some snow cover,
temperatures could be colder. Below zero temperatures are forecast
for many of the mountains and high valleys.

Wednesday through Friday...a warming trend develops as warmer
air aloft moves into the region. The amount of warming will depend
on the amount of mixing and amount of snow cover. Ensembles and
models show a trough passing over the region sometime around
Thursday. Trough looks to be generally dry and with best chances
for any precipitation over the Continental Divide region. There is
a significant spread in the speed and path of the trough so grids
represent an average of a range of solutions. --Pgw--

&&

Aviation...(for the 00z tafs through 00z Saturday evening)
issued at 251 PM MST Fri Dec 13 2019

Outside of gusty winds nearing or in excess of 25 knots at times
this afternoon at the kals, kcos and kpub taf sites, expect that VFR
conditions will continue over the taf sites into Saturday afternoon.

&&

Pub watches/warnings/advisories...
Winter Storm Warning until 5 PM MST Sunday for coz058>061.

Winter Storm Watch from late Saturday night through late Sunday
night for coz062-063-072>087.

Winter Storm Watch from Saturday afternoon through Sunday
afternoon for coz066-068.

&&

$$

National Weather Service Glossary of Abbreviations