Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS65 KBOU 270403

Area Forecast Discussion
National Weather Service Denver/Boulder CO
903 PM MST Sun Feb 26 2017

Issued at 903 PM MST Sun Feb 26 2017

The dry airmass remains in place over the state this evening with
clear or mostly clear skies across the mountains and northeast
plains. Increasing moisture is evident over Idaho and northern
Utah which will be moving eastward overnight. The dry air and
clear skies will allow for chilly temperatures during the pre-dawn
hours. With very little evidence that snow is falling in the
mountains this evening, backed off on the forecast of snow and
blowing snow overnight. As moisture increases by morning, the
chances for snow in the mountains will be going up through
tomorrow morning. Accumulations up to 5 inches are still expected
tomorrow in the high country. The expected increase in winds
overnight looks like it will be limited to the upper ridges, so
conditions in the valleys should remain benign overnight and
tomorrow morning. No other changes to the forecast were necessary
at this time.


.SHORT TERM...(This evening through Monday)
Issued at 345 PM MST Sun Feb 26 2017

A dry subsident airmass covering northern Colorado thanks to a
weak shortwave ridge passing overhead will shift east overnight.
In doing so, the light zonal flow aloft will become southwesterly
and also increase in speed with thermal packing aloft ahead of a
mid-level shortwave trough dropping down over the Great Basin.
Should see west-southwest sfc winds picking up speed through the
evening over the high elevations with the cross mtn wind
component approaching 45 kts by late tonight. Therefore should see
west winds of 25-40 mph in exposed mtn areas and gusts approaching
60 mph up around timberline as the night goes on. The gusty winds
are likely to produce blowing and drifting snow in open areas. At
lower elevations, winds not expected to be an issue except perhaps
near the base of the foothills where we may see an enhanced
downslope flow develop late.

On Monday...Swly flow aloft will continue to strengthen as the
upper trough nears the state. East of the mountain...falling sfc
pressure to our north will combine with the increasing swly flow
aloft to produce warm and gusty south-southwest winds on the
plains...particularly along the Palmer Divide east to Lincoln
County. Dry light fuels in the area...i.e. grasses and light
brush...will be susceptible with fire tomorrow afternoon due to
low RH and gusty winds. For that reason, have issued a Fireweather
Watch for fireweather zones 241...246 and 247 in east central
Colorado. The watch will run from 12 noon MST to 6 PM MST Monday
afternoon. Elsewhere...mid-level moisture will begin spreading
over northwest portions of the forecast area during the afternoon
ahead of the trough with scattered showers developing over higher
elevations. Snow level will gradually lower to the valley floors
by evening. Temperatures during the next 24 hours will run near to
slightly above average.

.LONG TERM...(Monday night through Sunday)
Issued at 345 PM MST Sun Feb 26 2017

Northern Colorado will be under the influence of an approaching
upper level trof Monday night and Tuesday. Improving orographic
flow in the mountains as winds shift w-nw Monday night and
Tuesday and improving lapse rates. Could see advisory type snow
amounts during these periods. Expect an associated cold front will
sweep across the plains late Monday night with shallow upslope
flow developing on Tuesday. As the upper trof kicks out over the
plains on Tuesday looks to be some showers that develop Tuesday
afternoon and evening. Focus still appears to be from Denver
southward down over the Palmer Divide with possible couple inches
of accumulation.

Behind the upper trof, a stronger northwest flow will develop over
much of the region with still some lingering snow showers in the
mountains and gusty winds. Expect an overall drying and warming
trend for all of Colorado, especially on Friday and Saturday.


.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 903 PM MST Sun Feb 26 2017

No aviations impacts are expected over the next 24 hours. A weak
easterly pressure gradient this evening has kept light easterly
winds going up to this point. Expect drainage southerly winds to
kick in over the next couple hours and then continue overnight.
More southerly flow is expected across the Palmer Divide and
northeast Colorado by tomorrow afternoon which will cause Denver
area airports to see increasing South and Southwest winds through
the day. Ceilings and visibilities should remain unrestricted
until later tomorrow night and Tuesday.


Fire Weather Watch Monday afternoon for COZ241-246-247.



LONG TERM...Entrekin
AVIATION...Dankers is the U.S. government's official web portal to all federal, state and local government web resources and services.