Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 261714 CCA
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
958 AM MST Sun Feb 26 2017

.UPDATE/CORRECTION TO 1ST PARAGRAPH...
Issued at 950 AM MST Sun Feb 26 2017

Subsidence and drying underway beneath a passing weak shortwave
ridge. Gusty southeast winds on the plains earlier this morning will
continue to weaken rest of this morning as the sfc pres gradient
relaxes. Furthermore the lighter zonal flow aloft at the present
time has equated to less wind in the high country. However, later
this afternoon with a shift to stronger southwesterly flow aloft
ahead of the next upper trough swinging down from the Pacific
northwest, should see wind speeds increase and become gusty on the
high ridges and passes resulting in areas of blowing snow,
particularly overnight. Otherwise, current forecast for today and
tonight appears to be on track. So, no noticeable changes to it at
this time.

&&

.SHORT TERM...(Today and tonight)
Issued at 416 AM MST Sun Feb 26 2017

Colorado is again in a dry pocket between short waves today. Weak
ridge axis will move over with winds aloft swinging from WNW to
WSW and decreasing a bit. The mountains will continue to have a
few light showers from a very shallow moisture layer, but amounts
should be minimal. Strong winds over the Front Range should
decrease a bit as flow decreases and shifts to a less favorable
direction for downward transport on the east side. Still, it will
be a cold and windy day above 10,000 feet. Winds on the plains are
a challenge today as there will be west winds along the Cheyenne
Ridge and a poorly defined mountain wave which will mainly be over
the higher elevations of the foothills. There will be some mixing
which could cause west winds to spread off the ridges/foothills a
little ways, but in general expect a trend toward east winds as
the synoptic scale high along our northern border, the tendency
for an anticyclone with the strong west flow through Cheyenne, and
the mountain wave would all point in that direction. Difficulty is
that Denver will be on the edge of all of this. This could affect
the temperatures as it will likely be 5-10 degrees warmer in any
wind spilling off the higher terrain. For now went with the idea
that most of the city will be in the cooler air this afternoon.

Moisture returns to the mountains tonight. Most of the night it
will still be a shallow layer, and the southwest direction is not
favorable for most of our mountains. Some deepening and
destabilization is expected late which should lead to a bit more
snow just before dawn.

.LONG TERM...(Monday through Saturday)
Issued at 416 AM MST Sun Feb 26 2017

Monday and Monday night, one short wave will drop out of the Pacific
Northwest and brush across northern CO, with weak to moderate mid
level qg ascent over the region through Monday evening, with qg
descent developing late. A weak surface low will be over
southeastern WY by 00z Tuesday, will then move into eastern NE by
12z Tuesday. Most of the snowfall with this first system will be
confined to the high country, with a few showers along the
northern border around 00z Tuesday. At the sfc, a shallow cold
front will slip south into late Monday night, in the 06-12z time
frame. Some shallow post frontal moisture around in the morning,
and generally dry aloft through 18z Tuesday. The next system is
progged to move out of northern AZ and across southern and eastern
Tuesday into Tuesday night. By 18z Tue, a weak sfc low will be
developing over sern CO. This feature is progged to move into swrn
KS by 00z Wednesday. Aside fm the snowfall in the mountains, the
mdls develop the best chc of snow south and southeast of Denver as
the moisture deepens with the passage of the next system as it
makes its way across southern CO Tuesday aftn into the evening,
approximately 21z-03z. The best chance of accumulating snowfall
south and southeast of Denver will occur at this time. Increasing
QG descent then sweeps fm west to east across the state after 06z
Wednesday with pcpn winding down across the cwa. Still looks like
snowfall in the mountains will be in the Winter Weather Advisory,
with 5-10 inches over 24 hrs, with enough wind to produce areas of
blowing snow above timberline. Most of this will be in the third
and fourth periods so too early to address with a highlight yet. A
ridge of high pressure over the west will bring another round of
drier and warmer weather to the region Thursday through Sunday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 950 AM MST Sun Feb 26 2017

Clear skies to be expected today under a weak upper level ridge.
The gusty southeast winds across southern and eastern portions of
the Denver metro area will continue to weaken rest of this
morning. By afternoon, light east-southeast winds will prevail. By
nightfall winds will back to a south-southwest winds at 6-14 kts
and remain there overnight. However, could see slightly stronger
west winds develop after midnight near the the foothills, such as
at KBJC.

&&

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

$$

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



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