Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 230324
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
924 PM MDT Fri Sep 22 2017

.UPDATE...
Issued at 924 PM MDT Fri Sep 22 2017

The airmass does not have enough instability to support
thunderstorms this evening, so will remove the mention from the
forecast. An initial frontal boundary has moved over the northeast
plains this evening with a few weak showers moving northward on
the strong southerly flow aloft. Any rainfall amounts have been
light. With the upper jet aloft over the state, the light
rainshowers will continue overnight. No other changes to the
forecast are necessary at this time.

&&

.SHORT TERM...(This evening through Saturday)
Issued at 318 PM MDT Fri Sep 22 2017

An upper level trough spinning over the Great Basin and Northern
Rockies will slowly shift eastward tonight and Saturday. Airmass
has becomes unstable over the mountains and nearby plains this
afternoon ahead of the upper level trough. Expect isolated to
scattered showers and storms to move across the higher terrain
through early evening. These storms will be quick moving due to
the strong flow aloft. Brief heavy rain, small hail, and wind
gusts to 50 mph will be possible with the thunderstorms. A cold
front will drop south across the eastern plains late this
afternoon and evening. Moisture will increase behind it. Expect a
few showers and storms to move onto the plains late this
afternoon and evening.

A moist east to southeast low level flow will bring cool and
cloudy conditions Saturday. Models show an area of rain over the
eastern plains during the late morning and afternoon associated
with the right entrance region of the jet. Will have 60-80 pops in
this area. Expect lighter precipitation for the higher terrain
and Front Range. Models have a large difference with temperatures
for Saturday. The NAM is showing upper 40s and lower 50s while the
GFS shows 60s for northeast Colorado. Will lean towards the
cooler NAM because of the expected cloud cover, but will not go as
cold.

.LONG TERM...(Saturday night through Friday)
Issued at 145 PM MDT Fri Sep 22 2017

The upper low will bottom out over Southern Utah by early Sunday
morning providing moderate QG ascent over much of Northern
Colorado. Will have likely pops for much of the area Saturday
night and Sunday with the highest pops over the Eastern plains.
The moisture further west is more shallow as mid levels are
rather dry with the strong southwest flow aloft. Some light snow
expected over higher elevations in the mountains, mainly above
9500 feet.  The low will then begin to slowly weaken and lift out
into Wyoming on Monday. However more troughiness will drop back
into the mean trof position through much of next week. Temperatures
will remain below normal for much of next week with a continued
chance of showers.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 924 PM MDT Fri Sep 22 2017

Northerly surface flow at low levels will continue overnight
Ceilings will remain VFR overnight, but will be lowering to 2000
to 4000 feet by 18z. Rain showers will develop through the
afternoon, with a slight chance of an embedded thunderstorm also
developing.

&&

.FIRE WEATHER...
Issued at 924 PM MDT Fri Sep 22 2017

Red Flag Warning has been allowed to expire, and cooler air is now
moving in from the south. Rain shower will be gradually increasing
overnight and through Saturday, bringing an end to the high fire
danger levels for the forseeable future.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

UPDATE...Dankers
SHORT TERM...Meier
LONG TERM...Entrekin
AVIATION...Dankers
FIRE WEATHER...Dankers


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