National Weather Service Forecast Discussion

000
FXUS65 KBOU 180332
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
832 PM MST Thu Jan 17 2019

.UPDATE...
Issued at 812 PM MST Thu Jan 17 2019

Broad upper trof will continue to move across the state tonight
and during the day on Friday. The initial first wave has moved out
of the mountains already, with some diminishment of snowfall seen
up along the divide per radar and webcams. Appears most of the
significant snow was over zone 31 and where Steamboat Springs
picked up about 4 inches so far. However, more snow is on the way
as regional radars showing next blob of moisture is already moving
into northwest Colorado this evening and more convective snowfall
over northern Utah. This should pick up snowfall rates over
Northern mountains later tonight and into Friday morning. Will let
current warnings and advisories run the course.

Across the northeast plains, a few rain and snow showers near the
Wyoming border for the rest of the evening with this initial wave.
Otherwise mainly dry tonight until the front arrives late Friday
morning. Appears best chance of any accumulating snowfall on the
plains will be along the Palmer Divide with the strong northerly
flow resulting in some upslope component south of Denver. Current
forecasts has this thinking built into forecast. Will also add
some fog over the far northeast plains tonight with moist,
southeast flow and dewpoints in the lower 30s.

&&

.SHORT TERM...(This evening through Friday)
Issued at 330 PM MST Thu Jan 17 2019

The big moisture blob continues to spread eastward, with clouds
over the northern mountains lowering and areas of light snow
starting to develop at this hour. The main area of more
significant snow with the shortwave trough is currently over Grand
Junction. This will work its way eastward during the night,
providing a period of moderate to briefly heavy snowfall as it
passes. Behind that there will be decent WNW orographic snowfall
for a few hours, then the flow will go more northerly and lighter by
late Friday morning. This will reduce the orographic snow and
shift it to favor different areas. This means the heaviest snow in
most areas will be with the band during the middle and later parts
of tonight, with lighter snow on Friday. Places that do well in
NW-NNW flow, like Summit county, may see accumulating snow last
longer during the day Friday though it doesn`t look particularly
heavy. The main adjustment to the forecast this afternoon was to
shift the timing of the snow with more tonight and less on Friday.

For the plains, everything looks a little faster than what was
previously advertised. The cold front will come in the morning
with some cooling and gusty north winds. Morning highs are likely,
but temperatures will still likely be in the 30s or maybe some
upper 20s later in the afternoon. Still expecting a decent area of
showers, mainly from about Denver southward, without much
accumulation. A combination of enhancement and a longer period of
snow from upslope on the Palmer Divide means there may be a better
chance of getting a couple inches of snow there.

.LONG TERM...(Friday night through Thursday) Issued at 330 PM MST
Thu Jan 17 2019

For Friday night into Saturday, the base of the upper trough will be
over the TX panhandle with the main cold push through the region.
Strong northerly winds on the plains will persist into the evening
hours on Friday with NW flow into the mountains. Lingering moisture
and lift provided by a 130 kt jet will keep light snow showers over
the mountains into Saturday morning. For the plains, light snow will
continue Friday evening with the main focus being areas with good
orographic influence from the North such as the Palmer Divide and
east into Elbert and Lincoln counties through midnight. For the
mountains an additional 1 to 2 inches will be possible overnight
into early Saturday with just a trace possible for the plains. By
mid-day Saturday the best energy will be over OK with increased
subsidence moving into Colorado. Upper level ridging will increase
over the region and help to increase temperatures and dry things
out for the weekend. Temperature-wise, lows in the 20s will
increase into the upper 40s and low 50s for Saturday and close to
60 by Sunday under mostly sunny skies.

The next weather system will be approaching the Pacific NW by Sunday
afternoon with decent model agreement that it will start to impact
CO 24 hours later. The positively tilted trough is expected to move
into the Great Basin Monday afternoon with a 115 kt jet rounding the
base of the trough with the left exit region over the central
mountains. Snow is expected to start in the mountains by Monday
afternoon and increase in coverage and intensity into Tuesday. A
cold push from the North will push into the Northern plains by
Monday evening. 700 mb model projections have temperatures dropping
into the -15 C range that would bring snow to the plains with lows
in the lower teens Monday night into Tuesday and possibly lower.
Amounts are still in question at this point but some accumulation
is expected. Temperatures on Tuesday will be in the lower 30s with
clearing in the afternoon on the plains. The mountains will still
see a slight chance of light snow with moisture laden NW flow and
orographics through Tuesday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 812 PM MST Thu Jan 17 2019

Surface winds have been rather erratic this evening but now seem
to be settling back to a drainage component from the south and
southeast. Cold front will arrive late Friday morning with
increasing northerly winds and brief chance of snow showers Friday
afternoon. Best chance of snow will be at APA with preferred
upslope northerly winds. Could see some higher gusts up to 35kt at
KDEN behind the front.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 5 PM MST Friday for COZ033-034.

Winter Storm Warning until 5 PM MST Friday for COZ031.

&&

$$

UPDATE...Entrekin
SHORT TERM...Gimmestad
LONG TERM...Bowen
AVIATION...Entrekin

NWS BOU Office Area Forecast Discussion