Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS65 KBOU 252150
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
350 PM MDT Sat Mar 25 2017

.SHORT TERM...(This evening through Sunday)
Issued at 350 PM MDT Sat Mar 25 2017

An upper level low that just crossed the southern NV/UT
borderlines has spread its cirrus shield over the state. As the
system pushes closer to the forecast area and as surface pressure
falls along the lee of the Rockies, southeasterly surface winds
are increasing. The upper low and surface low will deepen over
southeastern Colorado tomorrow morning, helping to wrap moisture
into northeastern Colorado overnight. A few showers will move into
the mountains this evening with snow levels starting around 9500
feet. Instability and increasing upward QG motion will help a few
rain showers spread over the plains later this evening. The main
cold front should push through the high country this evening then
out onto the plains after midnight. Snow levels are expected to
drop to near 7-7.5k feet with some rain/snow mix down to 6500
before sunrise. As the low spins over southeastern Colorado Sunday
morning, slightly cooler temperatures are expected to be pulled
down to bring snow levels possibly down to 6000 feet or slightly
lower. Overall, not expecting snow for most of the metro areas,
with less than an inch of snow for the Palmer Divide and less for
the Cheyenne Ridge. Some snow over the far eastern plains with
richer moisture and colder temperatures away from any downsloping
effects should result in amounts less than an inch as well.

As the system pulls away Sunday, upward QG motion will push east
as well, for a slow pull away of the precipitation. Northwesterly
flow aloft behind the low will keep light snow over the mountains,
for a total of 2 to 6 inches over the 24 hours. Temperatures
should be about 10 degrees colder. Moderate northerly winds on
the backside of the system will gust in the 20 to 35 mph range
over the plains during the morning and early afternoon.

.LONG TERM...(Sunday night through Saturday)
Issued at 350 PM MDT Sat Mar 25 2017

...Active weather pattern will remain in place this upcoming
week...

Upper level trough will continue to push east and out of the area
Sunday evening. Airmass will stabilize with any lingering showers
ending during the evening.

Attention will then turn toward next upper level storm system
digging into the southwestern U.S. Monday night and Tuesday. The
models seem to have slowed a bit more over the past 24 hours. In
advance of this system, we should see a round of convective
showers develop with daytime heating and sufficient moisture
Monday afternoon and night. A lead short wave kicking out ahead of
the main upper level trough may also help increase shower
coverage. At this time, most of the showers are expected to
develop over the mountains in the afternoon and then spread
northeast across the foothills and nearby adjacent plains through
Monday evening, while the eastern plains may stay dry.

Tuesday and Tuesday night, a closed low is expected to cut off in
eastern Arizona, and then drift slowly eastward into New Mexico
through Wednesday. There is large scale lift ahead of this system,
but given the low is so far south, the forecast area stays in
generally weak but persistent Q-G lift. Precipitable water values
of 0.5 to 0.6 inch across the plains are abnormally high, and
forecast lapse rates are neutral to slightly unstable. Therefore,
any type of forcing whether from Q-G or a light upslope flow
should be enough to generate widespread showers. Will also add
some thunder with forecast CAPE near 500 j/kg Tuesday afternoon in
and near the mountains. The wet weather should continue into
Wednesday before tapering off from northwest to southeast across
the area. Overall, this looks like a moderate precipitation event
shaping up across most of the forecast area. Snow levels are
advertised to be quite high with the very moist airmass in place
and lack of significant cold advection. Expect snow levels to
mostly range between 7500 and 8500 feet through this period,
possibly lowering to 6000-6500 feet by Wednesday morning with some
snow on the Palmer Divide area.

After that storm system exits the area, we`ll have a day or so of
drier weather and near normal temperatures for Thursday. Then the
next storm system may bring unsettled weather back into the
picture by late Friday or Saturday. This storm may end up farther
south but will still have above climatology PoPs and cooler
temperatures in the forecast for this period with a trough around.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 350 PM MDT Sat Mar 25 2017

VFR conditions are expected at Denver area air terminals through
tonight before a system pushes in. South- southeast winds of 5-15
kts will prevail through this evening before turning drainage
briefly, before a cold frontal passage after 09z where
northwesterly winds should blow for a few hours before trending
north-northeasterly and increase in speed Sunday morning. Ceilings
are expected to lower to around 6000-7000 ft agl closer to sunrise
and a 30-40 percent chance of rain showers. Ceilings will lower
even more to around 3000-4000 ft AGL after 12z. Showers are
expected to stay rain, except at APA where rain may mix with snow
as temperatures drop to near freezing. Snow accumulation is
expected to remain under half an inch, and occur mainly early to
mid morning.


&&

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

$$

SHORT TERM...Kriederman
LONG TERM...Barjenbruch
AVIATION...Kriederman


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.