Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 161523
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
923 AM MDT Mon Oct 16 2017

.UPDATE...
Issued at 907 AM MDT Mon Oct 16 2017

Northern Colorado remains under a moderate northwest flow pattern
today with some mountain wave cloudiness over East slopes and the
plains. Have adjusted forecast for more cloud cover this morning,
especially from Boulder county southward through Park and
Jefferson counties. May also need to adjust temperatures down just
a bit with the thicker cloud cover. With the mountain wave,
seeing some gusty winds over higher mountains and exposed east
slopes. Generally in the 15-25 mph range and higher gusts up to 45
mph over the peaks. Winds should decrease a bit by later this
afternoon.

&&

.SHORT TERM...(Today and tonight)
Issued at 443 AM MDT Mon Oct 16 2017

A little cirrus is passing over this morning signaling the warm
advection through the depth of the atmosphere. There is a little
enhancement from a Front Range mountain wave. All of this should
decrease later today as the ribbon of lift shifts eastward.
Similar clouds could return later tonight. In between we will be
in the heart of the warm ridge with very dry air aloft getting
mixed down in most areas. Dew points are already below zero above
about 10,000 feet, and this air should mix into the mountain
valleys this afternoon. The drying may a bit less with lighter
winds and deeper surface moisture out on the plains. Winds up to
about 50 mph at Berthoud Pass appear to be wave enhanced with much
less wind further west and below timberline. Expect this to also
diminish as the area of warm advection aloft moves east and flow
aloft decreases slightly.

Forecast temperatures for today look good. Valley cold pools are
about gone, but there will still be colder temperatures tonight in
the low spots and over the snow patches in Grand and Jackson
counties, so I dropped lows tonight a little in those places.

Very low humidities today, but strong winds generally limited to
higher elevations or places that have been cold or had recent
snow. Little area of interface between dry/windy on the east
slopes between about 8 and 10 thousand feet will have very high
fire danger today.

.LONG TERM...(Tuesday through Sunday)
Issued at 443 AM MDT Mon Oct 16 2017

An upper ridge axis moves eastward and across the CWA Tuesday
afternoon. The upper ridge flattens and zonal flow covers the CWA
on Wednesday. There is a weak upper trough to our north moving
eastward late Tuesday night and Wednesday morning. Flat upper
ridging stays around Wednesday night for us and the flow aloft
weakens and is southwesterly. Synoptic scale energy is benign on
Tuesday, Tuesday night, and Wednesday night, with weak downward
vertical velocity noted during the day Wednesday. The boundary
layer flow is south and southwesterly on Tuesday. There is normal
drainage low level flow Tuesday night, then some northwesterly
downsloping on Wednesday for most areas. Easterly winds are
progged late day Wednesday, with normal drainage patterns
Wednesday night. Moisture fields show a dry airmass for the CWA
through at least Wednesday night. Maybe just a bit of high
cloudiness here and there. There is no measurable precipitation on
the QPF fields. No pops. For temperatures, Tuesday`s highs are
quite similar to today`s highs. Wednesday are 0-1.5 C cooler than
Tuesday`s. For the later days, Thursday through Sunday, models
show weak troughiness and weak flow aloft over Colorado Thursday.
Southwesterly flow dominates on Friday with a bit stronger upper
trough to move across late Friday night into early Saturday.
North to northwesterly flow aloft is in place Saturday night with
upper ridging to move in again Sunday and Monday. The Friday
night/Saturday morning trough is not as substantial as it was on
previous model runs. There is some moisture and a chance for
precipitation, mostly over the mountains with the system Friday.
Temperatures stay above normals Thursday and Friday. They cool
off to a bit below normals on Saturday, then back above for
Sunday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 907 AM MDT Mon Oct 16 2017

VFR with continued mountain wave cloudiness through mid afternoon
hours. Surface winds will gradually will shift in a clockwise
manner, to w-nw this am and then around north and northeast by
late afternoon. Speeds should generally remain under 15kt.

&&

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

$$

UPDATE...Entrekin
SHORT TERM...Gimmestad
LONG TERM...RJK
AVIATION...Entrekin



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