Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 230201

Area Forecast Discussion
National Weather Service Denver/Boulder CO
801 PM MDT Sat Jul 22 2017

Issued at 754 PM MDT Sat Jul 22 2017

Tstm activity has ended over the CWA except for
a lone storm nr the CO-WY border. The HRRR and RAP
have been showing a trend for a few storms to dvlp
across nrn areas of the Urban Corridor between 9 pm
and 11 pm.  If the storm nr the CO-WY border holds
together and moves south then there is some potential
for this happening so will leave in a slight chc of
storms thru midnight.


.SHORT TERM...(This evening through Sunday)
Issued at 230 PM MDT Sat Jul 22 2017

A ridge of high pressure aloft will be over the Great Basin with
a weak northwesterly flow aloft over the cwa. Two areas of showers
and tstms, one exiting eastern CO at this time, with another area
extending from northern Weld County into Park County. This area
is expected to weaken as it moves slowly east the rest of this
aftn and early evening. Additional showers may develop as outflow
boundaries get generated but overall pops will only be the 10-20
percent range. Overnight, the airmass will stabilize and dry out.
On Sunday, upper ridge with weak north/northwesterly flow aloft
over the area. Less cloud cover will lead to warmer temperatures
and will adjust them up by a degree or two. Best chance of showers
and thunderstorms will be late in the day and located in or near
the higher terrain, too stable for storms over the northeast

.LONG TERM...(Sunday night through Saturday)
Issued at 230 PM MDT Sat Jul 22 2017

The upper ridge axis will shift a bit eastward and flatten a bit
Sunday evening. Enough embedded moisture and instability in the
flow to keep a few showers and storms going over the mountains
into the evening hours, with a low chance of an isolated high
based storm drifting off the Front Range into the nearby plains
before dissipating.

On Monday, the latest model forecast show a flatter ridge
orientation over the Great Basin and Central Rockies. It will
certainly turn warmer again, with above normal temperatures and highs
likely pushing into the mid 90s on the plains. The more westerly
flow could allow a few late day thunderstorms to sneak out of the
mountains each day, but overall most of the storms will be confined
to the high country.

By late Tuesday and Wednesday, the medium range models still
suggest the next push of monsoonal moisture to arrive. The 700-500
mb specific humidity and Precipitable Water (PW) progs show this
well. We will continue to point to the better PoPs for Wednesday
into Thursday, but even then the best potential for more
meaningful rainfall would remain in the mountains. We should see
temperatures return to near normal levels during this period.

For Friday into next weekend, the upper level ridge may begin to
retrograde and amplify into the Great Basin. This would result in
drier northwest flow aloft. Temperatures at this time are
expected hold near normal values.


.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 754 PM MDT Sat Jul 22 2017

An outflow bndry has moved across the airport with sely winds
developing. Winds will continue sely for the next few hours and
then go more sly by 06z. Latest hi res data shows some potential
for isold storms between 10 pm and midnight. For now will keep any
mention of storms out of taf and see how things evolve the next
few hours.




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