Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
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
000
FXUS65 KBOU 291733
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1133 AM MDT Sat Apr 29 2017

.UPDATE...
Issued at 1133 AM MDT Sat Apr 29 2017

Increasing lift has spread northward across eastern Colorado this
morning, enhancing the snowfall. The most significant snow has
remained over southeastern Colorado, but Denver is on the edge of
this forcing and it has kept the steady light snow going, with
orographic enhancement near the foothills. Boulder has had more
snow this morning than we had overnight, and there have been
significant accumulations in Jefferson and Douglas county. So we
will let the warnings continue for those areas. Still a steady
snow out around Limon as well. The heavier snow over southeastern
Colorado made a run at Lincoln county and then that band faded,
but there is a good chance that will happen again. In any event,
the steady light snow will continue into the evening out there.
We`ll continue to watch for any need to extend that warning later
in time or increase snow further north over Washington county or
the Holyoke area, but at this point the forecast is looking
alright.

&&

.SHORT TERM...(Today and tonight)
Issued at 446 AM MDT Sat Apr 29 2017

Light snow has been falling over the Front Range foothills and
adjacent plains overnight. Snow amounts of 6 to 10 inches have
been received from the foothills of Jefferson and Boulder
Counties. Accumulations around the Denver area and other plains
locations have been in the 2 to 5 inch range. Heavier
accumulations have occurred over the Palmer Divide where the
upslope winds have been enhanced by the higher terrain.

The heaviest part of the storm is well to our south as the center
of the upper low has set up over northern New Mexico. Northeast
Colorado has been left on the northern fringes of the storm
system, which will continue that way through tonight. This means
that additional snow accumulations this morning should be light.
By afternoon, snow should be winding down as the storm system
transitions out onto the southern plains. Since the southern Front
Range foothills and Palmer Divide have received significant
snowfall overnight, and will continue receiving light to moderate
snow this morning, will let the Winter Storm Warning continue.

The mountains may receive a couple inches of additional snow from
scattered snow shower activity, but it will not be enough to
warrant any highlights, so the Winter Weather Advisories have been
cancelled. A similar condition exists in the Denver area and to
the north and northeast. Any additional snow this morning will not
be enough to cause any impacts, so warnings and advisories in
those areas have been dropped.

Improving conditions are expected across the forecast area this
afternoon and evening as the center of the storm system moves into
northern Texas and drier air begins filtering into northern
Colorado. Clearing skies overnight will allow temperatures to drop
some 5 to 10 degrees cooler than this morning. This will probably
warrant a freeze warning, but will let the current weather clear
out of the region first.

.LONG TERM...(Sunday through Friday)
Issued at 446 AM MDT Sat Apr 29 2017

A stg storm system will be over cntrl KS Sunday morning and then
will move ene into IA by Sunday night.  Some wrap around pcpn may
still affect the far ern plains Sun morning and then gradually shift
eastward during the aftn. Pcpn will be snow in the morning and
then may switch back to rain by midday. Across the rest of the
area it will be dry except for a slight chc of aftn snow showers
in the mtns. Highs will be mostly in the 50s across the plains
however areas over the far ern plains may stay in the 40`s due to
lingering pcpn and cloud cover.

By Sun night moisture in nw flow aloft will increase in the mtns and
will lead to a good chc of snow due to favorable orographics.  In
addition pcpn may be enhanced as rgn will be in left fnt quadrant of
an upper level jet.  On Mon moisture will decrease in the mtns in
the morning so snowfall should gradually diminish.  By aftn the flow
aloft will be wnw with lapse rates in the 6-7 c/km range.  Cross-
sections still show enough moisture for sct showers in the mtns.  As
for highs readings across the plains will range from 55 to 60
degrees.

For Mon night the flow aloft will remain wnw with an upper level jet
overhead.  There also could be a wk disturbance moving across
overnight.  Cross-sections show more moisture embedded in the flow
with improving lapse rates.  Thus may see more snow in the mtns with
a slight chc of showers across the plains.

On Tue an upper level trough in nw flow will begin to affect the
area especially in the aftn thru Tue night.  As this feature moves
across there will be decent lapse rates and mid lvl ascent.  In
additon axis of upper level jet will put nrn CO in favored left fnt
quadrant.  Overall should see snow in the mtns Tue aftn into Tue
night with potential for heavy snow.  Across nern CO should see a
good chance of pcpn as well.  Soundings show temps will be wrm
enough for rain although pcpn could mix with snow late Tue night
down to 5000 ft.

For Wed there are some differences between the ECMWF and GFS.  The
ECMWF has the upper level trough se of the area by 12z Wed with
considerabe drying.  Thus it has pcpn ending before 12z.  Meanwhile
the GFS is slower with the upper level trough passage and still has
quite a bit of moisture affecting the area thru Wed morning with
upslope flow.  Thus it continues pcpn thru the morning hours.  For
now will keep in some pops as not sure about overall timing of the
system.

By Thu and Fri an upper level ridge will build into the rgn with dry
conditions expected along with much warmer temperatures.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1133 AM MDT Sat Apr 29 2017

Light snow will persist in the Denver area most of the afternoon,
but ceilings and visibilities are expected to gradually improve.
By 20z, MVFR conditions are expected to prevail, though there may
still be localized IFR. Lower clouds will dissipate between 00z
and 04z with VFR conditions after that.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until 6 PM MDT this evening for COZ036-039-
041-046-047.

&&

$$

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



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