Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 101659

Area Forecast Discussion
National Weather Service Denver/Boulder CO
959 AM MST Sat Mar 10 2018

Issued at 958 AM MST Sat Mar 10 2018

Cold front is moving across the Denver metro area this morning,
and a few degrees of cooling have been noted. We`ll cool temps a
couple degrees based on the amount of cooling seen to the north,
as temps are only in the mid to upper 30s in southeast Wyoming.
Airmass will become convective with the passing short wave to our
north, cold advection aloft, and daytime heating/destabilization.
We`re already getting some showers moving across the foothills,
and should see a few of these be capable of spreading southeast onto
the adjacent plains through the afternoon. Low levels are still
quite dry, so only light precipitation expected in lower
elevations. Could even see a few snow flurries as wet bulb zero
levels drop to near 5500 feet. Gusty northerly winds up to 45 mph
still expected across most of the eastern plains.

In the mountains, snow showers are bringing some accumulating snow
as expected. Overall, coverage will decrease this afternoon but
still expect local 1-2" snowfall given the convective nature of
the showers.


.SHORT TERM...(Today and tonight)
Issued at 345 AM MST Sat Mar 10 2018

Web cameras showing light snowfall has occurred over most of the
mountains. Accumulations appear light, less than 3 inches. Snow
showers will continue this morning and then end this afternoon.
Additional snowfall of up to 3 inches will be possible, with most
locations expected to see just a light dusting. East of the
mountains, cross sections show it should become unstable and moist
enough for showers to form. However, lower levels of the airmass
remain quite dry. If any precipitation reaches the ground, only
expect a few hundredths at most. Will have isolated showers in the
forecast for late this morning and early afternoon. By sunset,
airmass dries out across the area with mostly clear skies for the
overnight hours. It will be windy today behind a weak cold front.
Northerly winds are expected to gust to 45 mph over the eastern
plains. Highs today will be about 10 degrees cooler than
yesterday. Expect a chilly night due to a cooler airmass in place
and good radiational cooling. Lows should fall into the 20s across
northeast Colorado.

.LONG TERM...(Sunday through Friday)
Issued at 345 AM MST Sat Mar 10 2018

A swift mid-latitude undulating flow will provide a variety of
weather during days 2 through 7. It should start out dry but cool on
Sunday with a passing shortwave ridge. Winds will generally be light
although the eastern fringe of the CWA could see northerly winds of
15-25 mph during the late morning and afternoon hours. Sunday max
temps some 4-7 degs lower than those expected today. By Sunday
night, models show the sfc to 700 mb flow east of the mtns turning
nely/upslope in response to height and pressure falls on the West
Slope in advance of the mid-level shortwave trough containing a fair
amount of moisture swinging out of the lower Great Basin/Desert
Southwest. Model consensus shows this feature passing over western
Colorado early on Monday and across the state`s high country during
the day, apparently losing much of its energy and moisture along the
way. Matter of fact, the ECMWF shows little indication of this
feature by the time it reaches the CWA, possibly no more than some
mid and high-level clouds. The EC solution looks a bit underdone
with the moisture, and the NAM, GFS, Canadian and EC models all show
a 40-50kt speed max accompanying this wave on its passage. For now,
will hang onto the slight chance/chance PoPs for the high country
from late Sunday night through Monday evening with the best chance
for precip (no more than 45 pct) at the highest elevations Monday
afternoon. During this period, the chance of precip east of the
Front Range will be less than 10 pct, and that near the base of the

Tuesday night, as this dying wave exits the forecast area, strong
height rises over the Intermountain West signifying strong warming
aloft advance towards Colorado. By Wednesday, a high amplitude upper
ridge takes hold the Rocky Mtn region sending daytime temperatures
12 to 16 deg F above average. Mountains and high valleys are likely
to see their warmest temperatures on Wednesday with a warm southwest
flow and plenty of sunshine. That`s assuming the moisture/clouds
associated with another shortwave disturbance hangs back over the 4-
corners region for one more day. The plains and Palmer Divide will
likely see their warmest readings on Thursday when gusty west-
southwest winds spread down off the Front Range mtns. That`s
assuming the lee slope mtn wave clouds don`t become as thick as some
model cross sections indicate. That said, could the mercury topping
out in the lower 70s at many locations on the plains Thursday. As
this shortwave moisture spreads over the state, shower chances for
the the high country are expected to gradually increase starting
late on Wednesday. Snow levels will start quite high before lowering
Thursday into Friday with the passing shortwave. The plains should
see its cool down (albeit a small one) on Friday. However, it`s not
until Saturday when models generally agree in moving a cold front
and deeper moisture across the region. There`s much uncertainty in
the models regarding where and when precip will occur Friday and
Saturday. For now will trend temps down all areas on Saturday and
introduce higher PoPS for the high country and low PoPS for the
plains. It may be cold enough for precip on the plains to start out
as snow Saturday morning.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 958 AM MST Sat Mar 10 2018

VFR conditions will continue through Saturday morning. As a front
works its way southward through Colorado, winds will veer more
northerly and will prevail from 360 to 030 degrees by 18Z, with
sustained speeds around 15-18 knots with gusts to around 28 knots.
Have added VCSH into the DEN TAF as models are coming into
agreement with showers entering the area around 19Z. The beginning
wave of showers has already developed south of Laramie and will
work their way southeastward over the next few hours. As these
showers move through, winds may briefly gust between 30 to 35

By the evening, winds will decrease and will stay light from the
northeast through the day tomorrow. Skies will clear as well early
this evening.


Issued at 958 AM MST Sat Mar 10 2018

Winds will increase with gusts to 45 mph on the plains through
the afternoon. Humidities, however, will stay above 20% in most
areas given the cold advection. Nonetheless, grassland fire
danger will be elevated til around 6 PM when winds decrease.




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