Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Pueblo Colorado
616 PM MST Monday Mar 2 2015
issued at 615 PM MST Monday Mar 2 2015
Updated grids/forecast with latest observation and observation trends. Rose
Short term...(this evening through tuesday)
issued at 329 PM MST Monday Mar 2 2015
..strong winter weather system to move across region...
Impressive trough just off the Pacific West Coast was diving
southeast this afternoon. A vortmax within this trough over S calif
was lifting northeast. Baroclinic Leaf associated with this lead
wave was blossoming over the 4 corners region. Heavy snow has
recently redeveloped over Wolf Creek Pass per cdot web cams.
The leading edge of an Arctic air mass (noted by the impressive
pressure rises) was located over northwest Wyoming and was moving
This afternoon through tonight...
Lead shortwave will move across the region this evening into the
early morning hours. This wave will bring heavy snow to the San
Juans between through about midnight...with the snow decreasing
during the early morning hours. I anticipate intense snowfall rates
over the San Juans given all of the favorable parameters in place. I
anticipate we will see several thunder squalls (most or all ice
flashes) go over the San Juans this evening...and this is noted in
the Storm Prediction Center thunder products. I would not be surprised if we see well
over a foot of new snow with this event this evening.
Snow will increase over the central mountains later tonight as the
flow aloft transition from a south-southwest flow to more of a zonal flow...and
6-12 inches of new snow is likely by sunrise.
A couple of relatively brief snow squalls will be possible over the
San Luis valley...with the best chance of snow during the late
evening hours...roughly 8 PM to midnight.
The sangre Delaware cristos will also get into the act...with 3 to 6
inches of snow likely at the highest elevations. The Wet Mountains
and Pikes Peak should see very little accumulating snow with this
event (their snow will come Tuesday evening/night).
As for the plains...although I cannot rule out a rogue shower or
two...especially over the Palmer Divide and Raton Mesa...I do not
expect any accumulate precipitation on the plains when the front GOES through
later tonight. Simulations actually show very dry downslope air
developing behind the Pacific front as it move east over the plains
tonight. This front will scour out any remaining low level moisture
that is on the plains and it will keep the air mixed...so temperatures
tonight will remain relatively mild...some areas may not get below
freezing tonight across the lower elevations.
The Arctic cold front is expected to move across the El Paso County
region around the 10-11 am time frame and will drop south to New
Mexico by middle afternoon. Precipitation will develop behind the front..but
it will likely occur 2-4 hours after the front GOES by. Snow will
likely develop over the higher elevations of the Pikes Peak region
by middle afternoon and the rest of the Pikes Peak region by late
The snow over the San Juans will likely decrease...or even end...for
awhile tomorrow morning...but I anticipate it to redevelop as the 2nd
broader trough moves across the region. Since flow at 700 is
expected to remain W-SW...snow should redevelop over the favored
upslope regions. I do not expect excessive snowfall rates and I also
expect the winds to be much tamer over the higher terrain...so the
current Blizzard Warning will likely be downgraded to a Winter Storm
Warning by later shift.
Snow will continue over the central mountains...especially late in
the day as 700 mb flow GOES more northwesterly and colder air
continues to advect in along with the qg lift associated with the
Long term...(tuesday night through monday)
issued at 329 PM MST Monday Mar 2 2015
..wintry conditions continue through Wednesday...
Tuesday night through Wednesday...models are starting to merge
closer on the timing of events through Wednesday. The most active period
of the extended will occur from Tuesday night through Wednesday...as the upper
trough axis slides east across the 4 corners and the wind flow
shifts from a SW direction for the forecast area...to a brisk north-northwest
flow overnight into Wednesday. Snow will continue across the higher
terrain through Wednesday...but the challenge comes late Tuesday night and Wednesday
with trying to get a handle on what will happen across the Palmer
dvd and east plains. Hi res models indicate that upslope flow 00z Wednesday
will start pushing precipitation across the Palmer dvd and east plains in the
evening...but by 09z a stronger northerly push sweeps across the
Palmer producing a significant increase in snowfall as well as
rapidly deteriorating travel conditions. From 09z through 18z the
front drops south...with the focus area for greater snow accumulate and
dangerous travel conditions dropping south along the i25 corridor.
This should make for a tricky morning commute on Wednesday. The forecast
grids have been pushed in this direction to start reflecting this
next potential event...and current snow amount grids contain
advisory snow amounts. Will let following shifts revisit this for
possible highlights as well as adjustments to windgust grids. As for
temperatures...Wednesday is expected to be the coldest day of the extended period
with maximum temperatures in the teens and 20s. Snow is forecast to diminish
through the night...lingering the longest over the southern mts.
Thursday through Monday...long range models paint a ridge of high
pressure over the western US over the weekend...keeping the state
under northwest flow aloft. There may be some isolated snow over the
central mts on Sat...otherwise conditions should remain generally
dry with a warming trend developing. 30s on Thursday...40s on Friday...then
50s for Sat through Monday. Moore
Aviation...(for the 00z tafs through 00z Tuesday evening)
issued at 531 PM MST Monday Mar 2 2015
Updated taf for als given that precipitation type may stay as rain for
another hour or two before the switch over to snow occurs and IFR
conditions will be possible. This is due to disturbance coming
over the mountains...however the southwesterly origin of this
storm is also a fairly warm one...which could keep precipitation type as
rain for a little while longer. Important to note that if the
switch over to snow occurs...conditions could quickly drop into
the IFR category at kals.
Kcos and kpub tafs still look on track for now. Southerly winds
should cause IFR stratus to redevelop during the evening hours.
Will monitor this and make any adjustments as needed. Once winds
shift around from the southwest as Pacific front crosses the
mountains this should erode the stratus eastward and out of the
kcos and kpub terminals. Conditions should also improve at kals
around 06z. -Kt
Winter Storm Warning until 11 PM MST this evening for coz073.
Winter Weather Advisory until 5 PM MST Tuesday for coz059-064-
Winter Storm Warning until 5 PM MST Tuesday for coz058-060-061-
Blizzard Warning until 5 PM MST Tuesday for coz068.