Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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296
FXUS65 KBOU 240351
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
851 PM MST Thu Nov 23 2017

.UPDATE...
Issued at 850 PM MST Thu Nov 23 2017

Current forecast package appears to be on track with gradual
clearing out of mid and high-level mountain wave cloud band and
reduction in wind speeds. Have observed occasional burst of 15-20
kt westerly winds in and near the base of the Front Range
foothills in the couple of hours, but they too have decrease in
frequency. Otherwise, at this time plan to make just a few
minor adjustments to overnight temperatures and winds.

&&

.SHORT TERM...(This evening through Friday)
Issued at 133 PM MST Thu Nov 23 2017

A shortwave will bring stronger flow aloft with some increase in
the mountain winds and wave clouds overnight, then a cold front
and a little cooling aloft and mid level moisture by midday
Friday. The moisture layer should be pretty shallow, so the
forecast of scattered light showers still looks appropriate. Could
be an inch or two accumulation in some spots. Temperatures should
still be mild ahead of the front with highs slightly cooler than
today ahead of the front. Expecting temperatures on the plains to
drop into the 50s in the afternoon behind the front. All of this
is well covered in the current forecast.

.LONG TERM...(Friday night through Thursday)
Issued at 345 PM MST Thu Nov 23 2017

Models have a jet maximum of northwesterly flow aloft over the
CWA Friday night into Saturday afternoon. The flow aloft decreases
Saturday night as an upper ridge moves into Colorado. The ridge
axis is over the eastern border of Colorado late Sunday afternoon,
with the flow aloft become southwesterly Sunday night. There is
benign synoptic scale energy on the GS Omega fields Friday night
through Sunday night. For moisture, there is some in the upper
level mainly here and there Friday overnight through Sunday night.
The QPF fields show a tad of measurable precipitation over the
high mountains early Friday evening, then nothing through Sunday
night. Will keep some minor pops there. For temperatures,
Saturday`s highs will be 2-5 C colder than Friday`s highs.
Sunday`s highs are 4-7 C warmer than Saturday`s. For the later
day`s Monday through Thursday, models have strong southwesterly
flow aloft Monday. There is an upper trough with closed
circulation at it`s base near the four corners Tuesday at 12Z.
This weakens and pushes eastward into southwesterly Kansas by 12Z
Wednesday morning. There is upper ridging over the state
Wednesday, then another upper trough into Thursday, while the GFS
and Canadian have another upper trough move across Colorado on
Thursday. The medium range models are not in good sync, timing-
wise, with this system. Pops seem reasonable later Monday into
Tuesday, especially in the mountains.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 850 PM MST Thu Nov 23 2017

Drainage wind pattern has set up over the Denver metro area and
is likely to remain in place for the remainder of the night.
However, may still see the occasional west-southwest wind of
12-18kts near the base of the foothills, such as at KBJC.
Otherwise, VFR conditions are likely overnight.

&&

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

$$

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



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