Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Grand Junction Colorado
1136 PM MST sun Nov 23 2014
issued at 514 PM MST sun Nov 23 2014
Convective showers diminished quickly as the sunset and the latest
short term models show very little accumulation in the southern
and central Colorado mountains overnight. Therefore we have pulled down
winter highlights there. The northwest Colorado mountains will continue to see some
snowfall and accumulation overnight. All the Colorado high country
may see areas of blowing snow tonight with northwest winds of 20-35 miles per hour.
Snowfall will increase in intensity and coverage again on Monday
but the southern and central mountains are expected to stay below
advisory criteria of 6 inch accumulation.
Short term...(tonight through Monday night)
issued at 253 PM MST sun Nov 23 2014
Afternoon convective showers increased in coverage as anticipated
due to strong cold advection/instability and northwest orographics.
Eastern Utah and far western Colorado have only had isolated to
scattered light showers. Snow levels fall quickly into all valley
bottoms with sunset and remain there until Tuesday.
A downturn in snowfall expected tonight. Air mass stabilizes with
warm advection at 500mb. Orographic snowfall expected to continue
in the northwest Colorado mountains but the central mountains will see less additional
accumulations. But the convective component will keep snow in the
San Juans into the evening hours so have extended the advisories
there until 10pm.
A stronger and colder disturbance in northwest flow works through
western Colorado Monday afternoon and evening. This will again favor the
northwest Colorado mountains with convective snow accumulations. The Grand
Mesa and west elks will also see further accumulations but will be
more spotty in coverage. The overnight shift may evaluate if
highlights are still needed there into Monday. Snow accumulations
will continue Monday night mainly along Colorado northwest-facing slopes.
Long term...(tuesday through sunday)
issued at 253 PM MST sun Nov 23 2014
By Tuesday the trough is south and east of Colorado leaving the
region under northwesterly flow aloft. This pattern favors
orographic snow over the northern and north central mountains of
western Colorado. Winds aloft are quite high along the northern border
and in Wyoming. A few small embedded waves will also travel through the
flow and help with snow production over the northwest mountains of
Colorado Tuesday and Tuesday night.
A ridge slowly moves east over Southern California which will push the
moist air and better jet support to the northeast starting
Wednesday. Snow should decrease during the day Wednesday and into
The pattern remains dry through the end of the week. Temperatures
will increase to near normal or even above normal especially for
the lower valleys. The ridge starts to shift south again as
another storm enters the Pacific northwest. The pattern is more zonal
by Friday. The storm moves over the northern rockies late Friday
into Saturday skirting Colorado. For now the moisture remains north of
the state. Will have to watch this and see how it develops. A few
weak disturbances are indicated by models to quickly move over
eastern Utah and western Colorado and if the moisture drops farther south
than precipitation is possible.
Slight ridging by Sunday as the next system spins up off the Pacific
northwest coast. This would lend itself to dry conditions over the
Aviation...(for the 12z tafs through 12z Monday morning)
issued at 1136 PM MST sun Nov 23 2014
Conditions will deteriorate quickly after 09z this morning with
snow developing over the northern and central
mountains...extending to the southern mountains between 12z-16z.
IFR conditions in the mountains will be common...including the ski
country taf sites at kase...kege...and ktex. Snow lowering
ceilings/visible will be possible at the lower elevatad taf
sites...including kgjt...kril and kmtj. Improving conditions with
rising or dissipating ceilings is expected after 21z Monday afternoon.
Colorado...Winter Storm Warning until 6 PM MST Monday for coz004-005-010-