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fxus65 kbou 170915 
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Area forecast discussion
National Weather Service Denver/Boulder Colorado
315 am MDT Thu Oct 17 2019

Short term...(today and tonight)
issued at 244 am MDT Thu Oct 17 2019

High pressure ridge axis which is now over Colorado will shift
east into the Central Plains this afternoon as a weak upper trof
pushes into the northern rockies and northern Great Basin. The
resultant flow aloft will be increasing from the southwest across
much of Colorado. At the surface, Lee trof will develop with
increasing south and southeast winds across plains of eastern
Colorado.

Temperatures look to be slightly warmer today with a slight nudge
upwards of 700mb temperatures to around +11c. There will be
varying amounts of high level cloudiness in advance of the trof.
Initially, airmass looks too dry for any showers today, but by
later this evening and especially after midnight, moisture does
increase in the mountains and some support from upper jet and weak
upward ascent noted in qg fields. Cold advection with the trof
over night Thursday through early Friday as 700mb temperatures
drop to around zero. This will result in some snow showers for the
higher mountains but overall accumulations maybe a couple of
inches.

Expect gusty winds will increase later tonight as westerly flow
increases with approaching trof. Cross barrier flow would indicate
gusts in the 30- 50 mph range possible and including exposed east
slopes of the foothills. Lower elevations will remain dry with
the increasing downslope flow.

Long term...(friday through wednesday)
issued at 244 am MDT Thu Oct 17 2019

An upper level trough will move across the area on Fri, with some
mid level ascent, mainly in the morning. Cross-sections show
favorable moisture, in the mtns, thru midday with decreasing
moisture by aftn. Lapse rates are fcst to be in the 5-6 c/km
range. Thus will see periods of snow in the morning with activity
gradually decreasing thru the aftn. Over nern co, a cold front
will move across in the morning. This front combined with the
passage of the upper level trough, will lead to a chc of showers,
in the aftn, mainly along and south of a Denver to Akron line.
High across the plains will drop back into the 60.

For Fri night into Sat, drier air will spread over the area with
no precip expected. Highs will generally remain in the 60s over
nern Colorado.

Looking ahead to Sat night thru sun a stronger upper level trough
will affect the area. An upper level low will eventually develop
on sun over ern Wyoming and then move eastward into the Central Plains
by Sun night. Cross-sections show moisture increasing in the mtns
by Sat night and continuing thru the day on sun. Orographics will
be favorable with lapse rates in the 7-8 c/km range. In addition,
the position of the upper level jet, will put nrn Colorado in the
favorable left front quadrant. Thus there should be decent snow
in the mtns from late Sat night into sun. Across lower elevations,
a strong bora type front, will blast across the plains, on sun,
with the threat of high winds. There also could be some shower
activity, associated with the front, as it moves across the
plains. As for highs, readings will drop back into the 50s over
nern Colorado.

By Sun night, northwest flow aloft will be over the area as drier
air moves into the mtns. This will lead to decreasing snow in the
mtns. Across the plains, depending on the exact locaton of the
upper level low over the Central Plains, there could be some wrap
around precip. Thus areas closer to the Wyoming-NE border area may see
some precip during the evening hours.

On Mon, stg northest flow aloft will remain over the area. A
disturbance embedded in the flow may affect the mtns. Cross-
sections show favorable moisture associated with this feature.
Although lapse rates are rather stable, position of the upper
level jet, could lead to heavier banded snow in some mtn areas.
Across nern co, it will be dry and windy with highs remaining in
the 50s.

By Tue, drier air will spread across the area, in northwest flow
aloft, with only a slight chc of snow showers in the mtns. Highs
over nern Colorado will be near seasonal normals.

&&

Aviation...(for the 06z tafs through 06z Thursday night)
issued at 244 am MDT Thu Oct 17 2019

VFR with varying amounts of high level cloudiness through tonight.
Southwest surface winds expected to shift east and northeast this
afternoon as surface low shifts east of Denver this evening and
then turning northwest this evening.

&&

Fire weather...
issued at 244 am MDT Thu Oct 17 2019

Elevated fire danger increasing this afternoon with increasing
southwest flow aloft. This will result in gusty winds in the
mountains along with very dry conditions and humidity levels
dropping into the teens and higher single digits. There will also
be another area of elevated fire danger over the plains,
especially over Lincoln and Washington counties. However areal
coverage and speed intensity appear marginal for a red flag
warning.

Although winds will be gusty on Friday, temperatures will be
cooler with higher humidity levels which will decrease the fire
danger. On Saturday, fire danger will be elevated over South Park
and across portions of the Palmer Divide, due to gusty winds and
low humidity.



&&

Bou watches/warnings/advisories...
red flag warning from 11 am this morning to 7 PM MDT this
evening for coz211-213-214.

&&

$$

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