Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 171017
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
317 AM MST Fri Feb 17 2017

.SHORT TERM...(Today and tonight)
Issued at 221 AM MST Fri Feb 17 2017

Satellite imagery showing increasing clouds over the western
portions of the state with the approaching deformation. This will
increase cloud cover over the high country through the evening
into the morning hours increasing mid and upper level moisture on
the plains through the day. The entrenched ridge will move east
bringing a weak cold front over the plains between 9 and 10 am.
This will cool temperatures down into the 60s with 700 mb temp up
to 8C degrees cooler. There is minimal moisture with this push
but winds will accompany the front with gusts up to 30 mph on the
plains by the afternoon. This combined with the dry conditions on
the plains will increase fire weather concerns. More on that in
the fire weather section. For tonight increasing mid level
moisture will keep a cloud deck helping to moderate overnight
temperatures with lows in the mid 30s over the urban corridor. In
the high country the increased moisture and weak QG lift will
allow for a chance of light snow. Amounts will remain very light
with little to no accumulation expected.

.LONG TERM...(Saturday through Thursday)
Issued at 221 AM MST Fri Feb 17 2017

Unseasonably warm weather will continue through much of this
period, even with a few showers entering the forecast picture.

On Saturday, the powerful storm moving across southern California
and into the deep Desert Southwest will allow short wave ridging
over the state. There should be a shield of mid/high level
cloudiness spreading across Colorado ahead of this system, but
inversions will be shallow so temperatures should still warm into
the lower to mid 60s over most of the plains. In the mountains,
due to the short wave ridging, we`ll have to wait for some
destabilization in the afternoon for any chance of showers, and
those would be light with drier low levels still in place.

On Sunday, the powerful Southwest U.S. storm system will open up
and weaken as it lifts across the Central/Southern Rockies. There
is some weak Q-G lift noted and the airmass moistens and destabilizes
ahead of this system during the afternoon. As a result, we expect
to see more numerous showers develop over the mountains with a
few of these developing or spreading onto the plains late in the
afternoon or evening. Temperatures warm enough to support rain
showers into the high mountain valleys in the afternoon and early
evening, but then it turns cold enough to change over to snow
later in the evening. Accumulations in the high country appear to
be limited to a few inches given the short period of time
combining orographics, deeper moisture, and cold advection Sunday
night.

Monday and Tuesday, drier weather will re-establish itself. A flat
upper level ridge and lee trough will likely bring a return of
near 70F degree readings on the plains by Tuesday. Fire danger is
also expected to increase during this period with potential for
gusty winds as flow aloft strengthens.

The various medium range models are still showing another storm
system reaching the forecast area toward late Wednesday and
Thursday. They are still suggesting the track and thus main
precipitation shield of this storm to pass just to our north. That
track would still favor the mountains for accumulating snowfall,
but just a few showers and gusty winds on the plains. Will keep a
chance of precipitation in the forecast for now and watch for any
potential track changes over the next few days.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 221 AM MST Fri Feb 17 2017

VFR conditions are expected for the next 24 hours. Mid level
moisture will gradually increase with winds switching to SE then
east with the onset of anticyclonic flow from a cold front in the
morning. A building surface low will move winds back southerly
before returning to drainage. Speeds will remain between 10 and
15kt through the afternoon.

&&

.FIRE WEATHER...
Issued at 221 AM MST Fri Feb 17 2017

Near critical fire weather conditions exist for today with the
combination of poor RH recovery from yesterday and increasing
winds during the afternoon hours. A dry cold front will drop down
in the morning helping to decrease temperatures but increasing
wind gusts on the plains to 30 mph at times. Near critical fire
weather conditions will exist between 18 and 21z...especially over
portions of Lincoln county. Areas that saw some activity
yesterday will also be vulnerable with dry fuels however some
areas will see higher RH values.

&&

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

$$

SHORT TERM...Bowen
LONG TERM...Barjenbruch
AVIATION...Bowen
FIRE WEATHER...Bowen



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