Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 181709

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1109 AM MDT Sun Mar 18 2018

Issued at 1055 AM MDT Sun Mar 18 2018

Will slow down the cloudiness, pops, temerptures and weather in
the GFE grids based on radar, satellite, web cameras and
observations. Satellite pictures are now showing a closed
circulation developing at the bottom of the upper trough just
southwest of the four corners right now. Aside from those
alterations, will keep things as is in the GFE grids from 20Z


.SHORT TERM...(Today and tonight)
Issued at 327 AM MDT Sun Mar 18 2018

A vigorous upper level trough will move from the Great Basin across
Colorado with a closed low developing over sern CO/nern NM by early
this evening.  The low will then move quickly into the srn plains by
late tonight.  Overall will see decent mid level ascent as the
trough moves across later today and this evening with favorable
lapse rates.  Soundings show enough instability for some tstms as
well later this aftn and evening.

At the sfc, a low will intensify over sern CO this aftn and then
move eastward tonight. Low lvl flow over nern CO will become
mainly northerly this evening with gusty winds overnight. Big
question still remains as to how fast rain will change to snow at
lower elevations. Buffer soundings range from 03z along the front
range to around midnight further east. The wildcard is expected
convection which could turn rain to snow an hour or two earlier.
This would lead to potentially higher snow amounts than what I`m
currently forecasting. Thus overall confidence is still rather low
as to what may transpire. Naturally if convection ends up being
snow, snowfall rates of 2 to 3 inches per hour could occur for a
few hours in some places from Denver east and south. With
northerly low lvl flow my highest confidence would be over the
Palmer Divide towards Limon so will issue an advisory for those
areas. Other areas further north (Denver Metro for example) may
need an advisory as well but as mentioned above confidence is not
as high.

For later tonight the upper level system will move quickly eastward
with snow ending from west to east across the plains overnight.  In
the mountains orographic component will be favorable overnight and
cross-sections still show quite a bit of moisture so expect periods
of lighter snow will continue through the night.

.LONG TERM...(Monday through Saturday)
Issued at 327 AM MDT Sun Mar 18 2018

Storm system will be shifting east rather quickly and exiting the
eastern plains Monday morning. Still expect some light snow and
blowing snow over the eastern plains through mid to late morning,
but additional accumulations should be an inch or less. In the
mountains, scattered snow showers will likely continue off/on
through the day with modest orographics, moisture, and decent
instability. By afternoon, enough daytime heating and
destabilization combining with cold advection aloft may allow a
few light snow showers to spread from the higher terrain back
into the I-25 Corridor. Gusty north/northwest winds will continue
across the plains with gusts to 35-40 mph expected.

By Monday night, mainly dry conditions should prevail although
there`s still sufficient mid level moisture to keep a few snow
showers in the forecast across the mountains. Don`t expect more
than an inch or so of accumulation.

For Tuesday and Wednesday, look for drier and warmer weather to
redevelop as a flat upper level ridge builds over the Central
Rockies. Temperatures should rebound to above normal levels by
Wednesday as 700 mb temps warm above 0C. That should push highs
into the lower 60s over most of the plains.

Warm advection continues into Thursday when highs should push into
the lower 70s across the plains. Meanwhile, in the mountains a
subtropical plume of moisture arrives which should bring mostly
light rain and snow showers given the warm advection and southwest
flow aloft. There is an opportunity for accumulating snowfall
Thursday night into Friday across the mountains, depending on
strength of an embedded short wave and cold advection aloft.

Medium range models including the EC and GFS are still showing
potential for cooling and a chance of rain/snow by next weekend.
So far models seem rather progressive, but there`s still potential
for a deeper trough development.


.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1047 AM MDT Sun Mar 18 2018

The winds have come around to northeasterlies at DIA. Models keep
that until about 00Z, then more northerly winds much of tonight.
Current taf is pretty good with this. May postpone the onset of
lower ceilings in the TAF, maybe an hour or so. Ceilings should
get above BKN060 by 12Z.


Issued at 327 AM MDT Sun Mar 18 2018

Elevated fire danger will develop over Lincoln county this afternoon
due to gusty south to southwest winds and low humidity levels.  Fire
danger will decrease this evening as a cold front moves across.


Winter Weather Advisory until noon MDT Monday for COZ031-033>035.

Winter Weather Advisory from 7 PM this evening to 6 AM MDT
Monday for COZ041-046.



LONG TERM...Barjenbruch
FIRE WEATHER...RPK is the U.S. government's official web portal to all federal, state and local government web resources and services.