Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Denver/Boulder Colorado
347 am MDT Friday Mar 14 2014
Short term...sunny skies expected again today as dry air advects
across the region. Cross sections from the NAM show relative
humidities at or less than 60 percent through the entire
atmosphere until at least 03z. After that...moisture from the next
weather disturbance begins moving over northwest Colorado.
Pressure gradients across the state will be light through this
evening...meaning even less wind than yesterday. Moisture and
cloudiness from the weak upper low over Arizona and New Mexico is
expected to stay over southwest Colorado as that system progresses
eastward through Saturday morning.
In the first 24 hours of the forecast the only precipitation that
is mentioned is over the northern mountains after 06z tonight as
the leading edge of tomorrow/S weather disturbance approaches the
state. The main impact of this system will be felt during the day
tomorrow. Temperatures across the forecast area should be
comparable to what we saw yesterday.
Long term...another fast moving upper level trough will move across
the area on Sat along with a cold front. Cross-sections show decent
moisture in the mountains along with favorable orgraphics especially
through early afternoon. Thus should see areas of snow along with some
blowing snow. Accumulations should be generally in the 3 to 6 inch
range although a few spots could reach advisory criteria.
At lower elevations the low level flow over northestern Colorado will be mainly north-northwest
so upslope component will be lacking. However combination of some
middle level ascent and decent lapse rates may still allow for a chance of
rain and snow showers in the afternoon however do not expect any
accumulations at this time. Winds will be gusty with speeds to 40
miles per hour at times which could produce some blowing dust over the
plains. Highs on Sat will occur before noon with readings in the
45 to 50 degree range across northestern Colorado.
By Sat evening the upper level trough will move southeast of the area with
drier air spreading across northern Colorado. Thus precipitation should end by early
evening. For sun dry north-northwest flow aloft will be over the area. Once
again will see gusty winds at times over the mountains...foothills and
plains. Highs on sun should rise into the 55 to 60 degree range
over northestern Colorado.
For Sun night into Monday the flow aloft will gradually become more west-northwest
as a surface Lee trough intensifies east of the mountains winds will remain
gusty at times in the mountains and foothills and across the plains
especially near the Wyoming-NE border. With downslope low level flow temperatures
should warm quite a bit over northestern Colorado with readings in the middle 60s to
lower 70s. Some moisture will increase in the mountains by late afternoon
north of I-70 which could lead to a slight chance of showers.
By Monday night and Tuesday the European model (ecmwf) and GFS now show an upper level
trough affecting the area. The GFS now has a strong upper level low
closing off over eastern Colorado late Monday night which moves rapidly into
central Kansas by 18z Tuesday while the European model (ecmwf) has a more diffuse looking
trough affecting the area for the same time period. Overall should
see a good chance of snow in the mountains no matter what happens. Over
northestern Colorado the GFS solution would lead to a quick shot of precipitation late
Monday night into early Tuesday morning over the plains with less of a
chance in and near the foothills. Meanwhile the European model (ecmwf) would allow for a
better chance of precipitation in and near the foothills. For now will just keep
probability of precipitation in the slight chance category over northestern Colorado and adjust
By Wednesday and Thursday both the European model (ecmwf) and GFS show drier air spreading
across the area in west-northwest flow aloft so will have a dry forecast with
a warming trend.
Aviation...no aviation impacts today or tonight. Skies will be
clear with just a little bit of high cirrus at times. Winds will
remain less that 12 kts through the day as they trend to west and
southwesterly through the late morning and afternoon.