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Area forecast discussion 
National Weather Service Denver/Boulder Colorado
332 am MST sun Dec 28 2014

Short term...(today through tonight )
issued at 332 am MST sun Dec 28 2014

An increasing westerly flow aloft will be over Colorado today
ahead of an upper trough located over the northern rockies this
morning. Temperatures will be cool today but relatively mild in
comparison to what is coming. Across the northeast plains middle 20s
to middle 30s can be expected. Some wind will be possible in the
mountains and foothills. Open areas will be susceptible to blowing
snow especially through this morning. In the high country...
moisture will increase today through tonight with increasing middle
level qg ascent developing from the northwest. Overall
however...snow amounts will be light...in the 2 to 5 inch range
range. The higher amounts will favor zone 31. Have backed off the
onset of snow in the urban corridor and northeast plains until after
06z. Models are slow to develop snow. The Arctic front will push into
the Denver area towards 12z Monday...so best chance of snow will
occur after 09z.

Long term...(monday through saturday)
issued at 332 am MST sun Dec 28 2014

A broad longwave trough will be over North America Monday. A short
wave trough on the backside of it will continue to dive south across
the western states. For Colorado...an Arctic cold front will push
south across eastern Colorado early Monday. Temperatures will slowly
fall behind it through the day. A northeast upslope flow will
produce light snow across northeast Colorado starting Monday
morning. A jet overhead will also add lift.

A northeast to east upslope flow will continue around an Arctic
surface high as is dives southeast through Tuesday night. This will
cause light snow and cold air advection to persist Monday night and
Tuesday. Snowfall will be light...but with the long duration of
light snow could see 3 to 6 inches of snow along the Front Range and
a little more over the foothills.

Highs on Tuesday may struggle to climb above zero...especially is
the European model (ecmwf) is correct. It is about 4-5c colder in lower levels of the
airmass than the nam12 and GFS. On 06z Wednesday...a 1050mb surface
high is prognosticated to be over far northeast Colorado. Lows Tuesday
night will be well below zero in locations...and a few record lows
will be possible. The high will continue to dive southeast of
Colorado and southerly flow around it will start to warm
temperatures and bring any snow to an end Wednesday.

In the meantime...a closed off upper level low will be over the
Desert Southwest Wednesday. As it move east across the southern
rockies Thursday and Friday...it is expected to bring snow to
southern Colorado. Will have some low probability of precipitation in the mountains for
this. Chances for mountain snow will be better late Friday and into
next weekend as a northwest flow aloft develop develops behind the
exiting low. The northwest flow will keep temperatures cool and
below normal.

&&

Aviation...(for the tafs through 12z Monday morning)
issued at 332 am MST sun Dec 28 2014

VFR conditions will continue through 06z...with ils ceilings of 050-060
feet above ground level developing after in the 09-11z time frame. IFR ceilings/visibilities
will develop following the passage of an Arctic cold front 11-14z
Monday morning...with chance of snow at that time as well. A surface
trough along the Front Range this morning with south-southwesterly winds at
kden and kapa...could see occasional gusty westerly wind at kbjc in the 12z-
16z window. North-northeasterly wind shift will occur with the frontal passage
around 12z Monday morning.

&&

Bou watches/warnings/advisories...
none.
&&

$$

Short term...Cooper
long term...meier
aviation...Cooper

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