Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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838
FXUS65 KBOU 240216
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
816 PM MDT Sun Apr 23 2017

.UPDATE...
Issued at 810 PM MDT Sun Apr 23 2017

Showers will increase in the nrn mtns around midnight
as a disturbance moves across with a few inches of snow
possible abv 10000 ft. These showers should decrease
before 12z. Otherwise no changes needed to previous
fcst.

&&

.SHORT TERM...(This evening through Monday)
Issued at 341 PM MDT Sun Apr 23 2017

Southwest flow aloft across the state has brought warm
temperatures and mostly sunny skies to the forecast area.
Satellite imagery shows high level moisture continuing to work its
way out of Utah and over western Colorado. Deeper moisture is
located over northern Utah and eastern Nevada. The upper trough
associated with the deeper moisture is expected to track across
the mountains later tonight, producing some light snow, beginning
after midnight. Two to three inches of accumulation will be
possible. No precipitation is expected across the plains tomorrow,
but temperatures will be a little cooler in the wake of the
passing upper level disturbance. Gusty winds over the mountain
passes may also develop overnight with passage of the trough.

The mountain areas will see a brief break in snowfall tomorrow
morning, but then moisture and snow will increase again in the
afternoon as the next weather disturbance moves in to the state.

.LONG TERM...(Monday night through Sunday)
Issued at 341 PM MDT Sun Apr 23 2017

Models show a mean upper trough developing over the western
United States Monday night, then moving across the CWA Tuesday
afternoon and evening. The western/central U.S. are still troughy
Wednesday into the extended period.  There is northwesterly flow
aloft for the CWA Wednesday and Wednesday night with speeds of 30
to 65 knots. There is decent upward synoptic scale energy progged
on the QG Omega fields Monday evening well into Tuesday night.
Downward energy is in place Wednesday, then more upward moves in
Wednesday night. The low level wind fields show mostly upslope
flow Monday night well into Wednesday morning. There is a
appreciable cold front to move down late Tuesday afternoon/early
Wednesday evening. More normal diurnal wind patterns look to be in
place Wednesday afternoon and night. Moisture-wise, there is quite
a bit over the CWA monday night, but not much in the lower levels
of the plains. There is some dry late Monday night and Tuesday
morning, then it increases. Moisture is pretty deep for all areas
Tuesday afternoon late and Tuesday evening. It decreases early
Wednesday morning. There is some moisture around both Wednesday
and Wednesday night in the northwesterly flow aloft. There is some
CAPE around Monday night through Tuesday evening; nothing great,
with the highest numbers over the mountains Tuesday afternoon. The
QPF fields show quite a bit of measurable precipitation for the
CWA over the five periods. There are decent amounts over the
mountains Monday night. Another good shot occurs Tuesday afternoon
and evening mainly over the plains. Wednesday looks drier early,
but there is still some convective showers late in the day for
much of the CWA with some QPF. The Tuesday afternoon and evening
periods have some snow east of the mountains, especially over the
Palmer ridge. Will go with "likely" pops in the mountains Monday
night and Tuesday afternoon/evening for much of the CWA. Other-
wise, 10-40% pops will fill in the gaps. For temperatures,
Tuesday`s highs are 7-11 C colder than Monday`s. Wednesday`s highs
are 1-4 C warmer than Tuesday`s. For the later day`s, Thursday
through Sunday, models have Colorado in an upper troughiness
Thursday into Friday, then an upper closed low is around Friday
night into Saturday evening. Some of the models show it in a
favorable position for lots of weather.  By Sunday, most models
bring in upper ridging. Models do not agree very well with each
other by Saturday and Sunday with the positions of the main
features. Temperatures look to be below seasonal normals all four
days. Some of the models are cold enough for a decent snowfall
over the plains, certainly for the urban corridor Friday night and
Saturday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 810 PM MDT Sun Apr 23 2017

Push of nwly winds were approaching the airport and should be
there by 03z. Not exactly sure where these winds are coming from
but will keep them in thru 05z with a gradually change back to ssw
by 06z. Another weak surge may come in around 09z-10z with a brief
shift to nly for a few hours.

&&

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

$$

UPDATE...RPK
SHORT TERM...Dankers
LONG TERM...RJK
AVIATION...RPK



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