Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 180240

Area Forecast Discussion
National Weather Service Denver/Boulder CO
840 PM MDT Tue Oct 17 2017

Issued at 840 PM MDT Tue Oct 17 2017

No need for any updates to the forecast at this time. Dry west-
northwesterly flow aloft continues with some high level moisture
producing lenticular wave clouds at times. Wind speeds at mountain
top level are only about 20-25 knots with stronger flow further
aloft. Hence, winds at the surface are being driven by the weak
surface pressure gradients. Tomorrow looks like another mostly
sunny and warm day. A weak frontal surge is expected over the
northeast plains during the afternoon, but not much impact is


.SHORT TERM...(This evening through Wednesday)
Issued at 223 PM MDT Tue Oct 17 2017

Satellite WV shows an extensive ridge over the southern portions
of the Great Basin with a warm belt of moisture moving up and into
Colorado from the NW. This will help bring in an upper disturbance
and sfc cold front Wednesday afternoon. This will be a dry front
with the main impacts being variable wind directions through the
afternoon tomorrow. For the rest of the evening conditions will be
mostly clear with increasing mid level clouds and lows slightly
warmer than last night. Winds will pick up by the afternoon ahead
of the front from the north on the plains with mostly westerly to
variable directions closer to the foothills with the help of a lee
side low. Temperatures will once again be above average with highs
in the 70s on the plains and 50s to 60s in the mountains and

.LONG TERM...(Wednesday night through Tuesday)
Issued at 311 PM MDT Tue Oct 17 2017

Upper ridging is over the CWA Wednesday night with weak flow
aloft. Weak southwesterly flow aloft will dominate on Thursday
into the evening before a very weak upper trough moves across the
CWA late Thursday night/early Friday morning. Increasing west-
southwesterly flow aloft is progged on Friday into Friday night.
The synoptic scale energy is benign through midday Friday, then
there is weak upward motion indicated Friday afternoon and night.
The low level pressure and wind fields point to normal diurnal
wind patterns Wednesday night and Thursday night. There will be
southerlies on Thursday with a weak Denver cyclone possibly.
Southwesterlies are progged on Friday, with a cold front and
north-northwesterly winds later Friday evening and overnight. For
moisture Wednesday night, it starts out pretty dry, then it
moistens up in the mid and upper levels with an incoming weak
trough. That stays in place Thursday into Thursday evening. It
dries out again overnight into Friday morning. By afternoon
moisture increases again with the next upper trough. A couple of
the models now show a tad of measurable precipitation over the
southwestern CWA late day Thursday. There is also some minor
amounts progged over the mountains Friday night. For pops, will
go with "slight chance"s over the mountains south of I-70 on
Thursday afternoon and evening. Will go with 10-30%s for the
mountains Friday night. For temperatures, Thursday`s highs are
similar to Wednesday`s and Friday`s are a bit warmer than
Thursday`s. For the later days, Saturday through Tuesday, models
bring the upper trough across the CWA on Saturday. By Sunday,
continuing through Tuesday, there is an upper ridge over the
southwestern United States with weak northwesterly flow aloft for
the CWA. There is a bit of moisture and limited pops early
Saturday, then it is dry again into the middle of next week.
Temperatures will be a below seasonal normals on Saturday, then
return to above normals readings Sunday through Tuesday.


.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 840 PM MDT Tue Oct 17 2017

No aviation impacts expected through the next 24 hours as skies
remain mostly clear, except for mountain wave cloudiness. Drainage
winds tonight will give way to east or northeast winds during the




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