Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 210914

Area Forecast Discussion
National Weather Service Denver/Boulder CO
314 AM MDT Tue Aug 21 2018

.SHORT TERM...(Today and tonight)
Issued at 313 AM MDT Tue Aug 21 2018

Upper level ridge over the Southern Rockies will shift east into
Texas today. This will produce a southwest flow aloft over
Colorado. Monsoon moisture will lift out of the Desert Southwest
and into Colorado today. Precipitable water values show this
increase in moisture and climb above an inch along the Front Range
and across the eastern plains. A short wave trough moving into
Arizona this morning will rotate into Colorado this evening. In
addition to the short wave, the right entrance region of the jet
will also provide lift today and tonight.

There is an area of showers at this time that extends from
southeast Wyoming southwest into northern Utah. Appears this is
associated with the jet. The Front Range and eastern plains are
dry at this time with dew points in the lower 40s. Expect the
showers to have a tough time making it over eastern Colorado this
morning. Best chance for showers this morning will be over
northern areas.

Showers and thunderstorms are expected to form over western
Colorado early this afternoon and spread eastward across the state
this afternoon and tonight. Instability will be on the low side,
generally less than 500 J/kg, so convection should not be severe.
Models are in decent agreement with the set up through tonight, so
feel comfortable increasing pops into the 70-80 percent range.

.LONG TERM...(Wednesday through Monday)
Issued at 313 AM MDT Tue Aug 21 2018

It will remain cool and unsettled on Wednesday. The system will be
exiting to the east in the morning, with lingering showers and
thunderstorms over the northeast plains. The models still generate
qpf over the cwa in the afternoon, with the best chance of
precipitation in the mountains with more isolated coverage across
the plains. On Thursday a drier west to northwesterly flow aloft
will be over the cwa. An upper level trough axis will move across
northern Colorado with moderate mid level QG descent by 18z.
Moderate flow aloft coupled with mid level subsidence should allow
for fairly windy conditions in the Front Range Mountains and
Foothills. Above timberline and exposed eastern slopes could see
some gusts around 50 mph, especially in the morning. There could
be some shower activity in the mountains but overall expect just
10-20 percent coverage, primarily west/northwest facing slopes.
The gusty winds will help temperatures climb back to normal in the
afternoon. Friday and Saturday will be mostly dry and warm with
the best chance of thunderstorms over the mountains. A ridge aloft
will be over the state on Friday, it then shifts east on
Saturday, centering itself over ern Texas and Oklahoma. This will
result in a southwesterly flow aloft over Colorado. Subtropical
moisture will increase over western CO late Saturday through
Monday. The models paint the best qpf in the mountains through
this period, so will keep most the pops there. Overall,
temperatures will run at or slightly above normal Thursday through


.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 313 AM MDT Tue Aug 21 2018

Smoke is expected to decrease a little today. Visibility may
still be restricted to 5 miles this morning before improving. An
upper level system is expected to bring showers late this
afternoon and evening. A few storms are expected to be mixed in as
well. After the rain moves off to the east, low clouds with
ceilings below 1000 feet are expected across the Denver area after
06Z Wednesday. There is also a chance for fog with visibility
around a quarter mile towards 12Z Wednesday.




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