Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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566
FXUS65 KBOU 231704
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1004 AM MST Mon Jan 23 2017

.UPDATE...
Issued at 1005 AM MST Mon Jan 23 2017

Forecast looks on track today. Only adjustments were to reduce
cloud cover along and east of I-25 where latest satellite imagery
show clear skies. Southwest winds from the foothills east to
Kansas are picking up today, and combined with clear skies should
allow temperatures to warm well into the 50s most areas other than
the far northeast, which should top out around 50.

Mountain snow is ongoing and should continue across the western
slope where southwest facing ranges will see light snow most of
the day. Winter Weather Advisory for the Park and northern Gore
Ranges looks good through Tuesday evening.

&&

.SHORT TERM...(Today and tonight)
Issued at 357 AM MST Mon Jan 23 2017

After a round of snow in the mountains last evening, there has
not been much overnight. Low level moisture is gradually
increasing along with some destabilization and increased winds
aloft and we are starting to see an increase in both the ridgetop
orographic snow, and some shallow banding upstream. This should
steadily increase today, and there may even be a little bit of
CAPE to work with this afternoon. However, the winds are never
really enough for much orographic snow and the best lift with this
system will stay north of Colorado. We have issued an advisory for
the Park range which does better in WSW flow and will get a bit
more out of the dynamics as well. The wild card is the showers,
but we are counting on the heavy showers to be transient and more
numerous near the Wyoming border. More populated mountain areas
further south should still see decent snow accumulations over the
next 36 hours, but the threat of heavy snow looks pretty limited.

For the plains there may be some attempts at showers through today
as the increasing moist and unstable airmass moves in. However the
downslope winds will also be increasing, so there should continue
to be a dry layer near the ground. We will have low PoPs through
this evening as there may be some light showers that do surface.
Temperatures will be pretty warm today, so this would be rain on
the plains. The surface low will consolidate northeast of us
tonight, bringing a shift to northerly winds early Tuesday
morning. A better chance of snow showers will begin at that time,
mainly near the northern border.

.LONG TERM...(Tuesday through Sunday)
Issued at 357 AM MST Mon Jan 23 2017

The upper low will be over far northeastern Colorado while the
surface low pushes into southwestern Nebraska. A cold front will
push down over the state while mid and upper level winds turn
northwesterly. Moderate snow will continue over the mountains in
the favored northwest flow, and the plains will see a chance of
snow through the daylight hours as weak upslope flow occurs. The
winds aloft will mix down and produce gusty winds across the
plains, up to 40 mph over the northeastern corner, possibly producing
patchy blowing snow. Amounts are expected to be an inch or less.
Over the mountains, another 2 to 5 inches of snow should fall
during the day before moisture decreases. Maximum temperatures
Tuesday should be 10 to 20 degrees colder behind the front.

With the system pushing east, the snow will come to an end quickly
over the plains during the evening as upslope flow becomes a
drying northwesterly direction. Snow will continue in the
mountains, though at lighter rates as moisture decreases.

A broad trough over central Canada and into the central US will
slowly move east but keep Colorado in northwesterly flow aloft
Wednesday through Friday. This will keep colder than average
temperatures over the region and limited moisture will keep light
snow in the mountains in the favored northwesterly flow. The
plains should remain dry.

An upper ridge will build into the western US this weekend with a
shortwave trough to sink south in northwesterly flow along the lee
of the Rockies on Monday. Look for temperatures to rebound to
near or above average and mostly dry conditions.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1005 AM MST Mon Jan 23 2017

VFR today and tonight with increasing southwest winds during the
day today at all three terminals. Could see gusts at DEN in the
20-25kt range. Tonight winds should decrease as the surface low
develops and shifts east. With the translation east and deepening
of the low, a cold front will reach the three terminals before
sunrise Tuesday. Expect weakening southwest winds transitioning to
light westerly until frontal passage around 10Z or so. Winds will
shift to the north and increase to 10-15 kts or so. Still
expecting possible MVFR conditions midday Tuesday with any snow
showers that develop. The PROB30 in the DEN TAF covers this well
for now. If snow develops, amounts should be an inch or less at
the three terminals.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 5 PM MST Tuesday for COZ031.

&&

$$

UPDATE...Schlatter
SHORT TERM...Gimmestad
LONG TERM...Kriederman
AVIATION...Schlatter



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