Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 301024

Area Forecast Discussion
National Weather Service Denver/Boulder CO
424 AM MDT Fri Sep 30 2016

.SHORT TERM...(Today and tonight)
Issued at 424 AM MDT Fri Sep 30 2016

A stream of moist air is moving over the state this morning,
mainly over the mountains. Shower activity over the mountains
early this morning should increase through today as diurnal
warming helps the airmass become slightly unstable. Light radar
echoes have developed over the north central mountain counties,
but the heavier echoes so far have been over the west slope. The
moisture is moving over the state on deep south to southwesterly
flow as an upper ridge axis holds its position over western
Kansas. The southerly fetch will make it difficult for much
precipitation to move over northeast Colorado until later this
afternoon and evening. And even then, areas along the I-25
corridor may be the only ones to see any rainfall. The forecast
will have the highest chances of precipitation over the mountains.
By afternoon, the atmosphere may become unstable enough to support
thunderstorm activity, but only moderate rainfall is expected.

Temperatures today will be held back by the increasing cloud
cover, but still a couple degrees warmer than normal. Later
tonight, temperatures in the mountains will cool enough for snow
to fall at elevations above 8000 feet. Shower activity will be
winding down at that time, so no significant accumulations are

.LONG TERM...(Saturday through Thursday)
Issued at 424 AM MDT Fri Sep 30 2016

A flat upper level ridge will be over the area on Sat and will
become more swly on Sun as an upper level trough deepens over the
Pacific NW.  There will be some mid lvl moisture over the rgn on
Sat with not as much on Sun. Over instability is not that great
either day with capes aob blo 500 j/kg. Overall the best chc of
convection looks to be on Sat over the higher terrain with only
isold activity over the plains. Temps will remain abv normal both
days with readings in the upper 70s to lower 80s across nern CO.

On Mon swly flow aloft will increase as an upper level low moves
into the Great Basin.  Surface low pres will intensify east of the
mtns with gusty ssw winds expected over the plains with increasing
fire danger.  Moisture will increase in the mtns by aftn mainly west
of the divide which will lead to a chc of showers and storms as some
mid lvl qg ascent moves in.  As for highs temps will remain above
normal especially across nern CO as highs reach the lower to mid

For Mon Night into Tue the upper level low will move ene across WY
with the flow aloft becoming more wnw across nrn CO.  Cross-sections
show best moisture will stay to the north of the area with downward
forcing in place.  Will keep in a chc of showers mainly north of I-
70 across the higher terrain.  Temps will be cold enough for some
snow in the mtns with a mix across the higher valleys.  Over nern CO
will keep in a slight chc of rain showers.  Winds will increase in
the foothills and across the plains as a bora type fnt moves across
late Mon Night into Tue morning.  As for highs readings will drop
into the 60s across the plains.

By Tue Night into Wed the upper level low will move into the wrn
Dakota`s with wnw flow aloft remaining over the area.  There are
some differences between the ECMWF and GFS with handling of
moisture. The GFS shows an increase in moisture Tue night into
early Wed morning while the ECMWF has this moisture increase late
Tue night thru the day on Wed. Overall should see a better chc of
snow in the mtns Tue night possibly into Wed depending on the
timing of this moisture as orographics will be favorable. Over the
nern CO will see a slight chc of showers. Winds will remain gusty
across the area as well. Highs over nern CO will remain in the

For Wed Night into Thu the flow aloft will continue wnw as drier air
spreads across the area.  This should lead to a dry pattern with
temps warming back to nr seasonal levels.


.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 424 AM MDT Fri Sep 30 2016

Mountain areas to the west of Denver will be receiving rainfall
through much of the day as moisture streams over the state from
the south. However, the Denver area won`t see much precipitation
until the afternoon, and most of this will fall over the western
suburbs. A few showers may move over the Denver airports with high
ceilings and light rainfall amounts. Ceilings should remain above
6000 feet through the afternoon and evening. Winds will be
generally light as a weak lee trough forms along the Front Range,
but pressure gradients across the state remain weak. Aviation
impacts should be minimal and the TAF package will only mention
VCSH for the time being.




SHORT TERM...Dankers
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