Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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243
FXUS65 KBOU 101023
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
323 AM MST Sun Dec 10 2017

.SHORT TERM...(Today and tonight)
Issued at 320 AM MST Sun Dec 10 2017

An abnormally warm and dry antecedent air mass is forecast to
remain over the forecast domain through tonight. A subtle eastward
displacement in the strong blocking ridge pattern over the
western CONUS will lead to a reduction in the northwesterly flow
aloft and thus result in lighter sfc winds today. However, models
indicate an increase in northwesterly wind speeds across the
northeast corner of the CWA late this afternoon through this
evening in response to falling pressure in advance of a weak
pressure surge and slightly cooler, moist air racing south through
ern Wyoming. This hardly noticeable feature on satellite and sfc
pres/wind analyzes at the moment is forecast to brush nern
Colorado between midnight and 6 AM MST tonight. With its passage,
may see some mid-level clouds, an uptick in winds and a sudden
dip in temperature mainly across the nern corner of the CWA.
Otherwise, the forecast area is in for another day of nearly
cloudless skies, unseasonably warm temperatures and low relative
humidity. For that reason, the fire danger will remain elevated,
but not the level observed yesterday with the stronger winds.
High temps on the plains today as much as 21 deg F above average,
and anywhere from 8 to 15 deg F above average in the high
country. The high mtn valleys will again be the slowest to warm
beneath a shallow layer of very cold, nearly saturated air.
However, should see this sfc based inversion layer mix out quickly
by late by this morning with heating and drying from above.


.LONG TERM...(Monday through Saturday)
Issued at 320 AM MST Sun Dec 10 2017

Strong ridge of high pressure will remain parked over the Western
U.S. for much of the upcoming week. This will result in a moderate
northwest flow over Colorado. With this flow, the airmass will
remain dry and warm with readings way above normal (10-20 degrees) for
this time of year. There will be some slight cooling on Monday as
a weak ripple in the flow brushes northeast Colorado and surface
high pressure builds into Colorado from the north. Still some
elevated fire weather concerns on Monday afternoon with breezy
conditions on the northeast plains but humidities not quite dry
enough for any fire hilites. Warmer again on Tuesday but then
more cooling again late Wednesday and Thursday as another weak
system drops into the central plains. Again, airmass still very
dry so no chances of perception.

More uncertainty in the forecast trend for this weekend as long
range models show a weak wave moving through the flow on Saturday.
GFS is the outlier here as it now drops more energy as a closed
low off Southern California on Saturday but still a lot of
variation in the ensemble data. At this point, a chance of snow
in the mountains for late Friday night and Saturday but will keep
forecast dry over lower elevations.

&&

.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 320 AM MST Sun Dec 10 2017

VFR conditions next 24 hours, with generally light winds. Wind
south-southwest this morning, turning northeast in the afternoon,
then back to a light south-southwest drainage wind pattern after
sunset.

&&

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

$$

SHORT TERM...Baker
LONG TERM...Entrekin
AVIATION...Baker



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