National Weather Service Forecast Discussion

000
FXUS65 KBOU 091534
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
934 AM MDT Thu Apr 9 2020

.UPDATE...
Issued at 925 AM MDT Thu Apr 9 2020

Clouds have been slower to develop this morning, and expect the
same to hold true for the showers this afternoon and evening.
Consequently, have pushed the timing back by about 3 hours. Also
bumped the max temperatures up by 3 degrees or so with a couple of
hours of additional heating expected.

&&

.SHORT TERM...(Today and tonight)
Issued at 439 AM MDT Thu Apr 9 2020

Northern Colorado is under a negatively tilted upper ridge axis
this morning which is downstream from a cold upper low spinning
over southern California. At lower levels, a weak cold front from
the north moved across the plains last evening which has cooled
off temperatures down to near seasonal normals. The upper low over
southern California will be circulating mid and upper level
moisture over Colorado through today. By this afternoon,
deformation band clouds and showers will develop over the central
part of the state, some of which will be over Park County and the
southern Front Range foothills. The increasing cloudiness through
the day will also keep temperatures about 10 to 15 degrees cooler
than yesterday. Snow levels will be quite high since the moisture
will be coming up from the south. So the forecast will have light
snow over the mountains and rain at lower elevations, starting
after 3 PM and continuing much of tonight. Snow accumulations will
be less than a couple inches. According to high resolution short
range models, most precipitation should be over by about midnight.

.LONG TERM...(Friday through Wednesday)
Issued at 439 AM MDT Thu Apr 9 2020

An upper level low will remain over srn California, on Fri, with
weak west to southwest flow aloft. At the sfc, a lee trough will
develop along the front range. There will still be enough moisture
around to keep in a chc of showers over the higher terrain with a
slight chc over the plains. Highs will be warmer, across nern CO,
with readings in the upper 60s to lower 70s.

On Sat, the upper level low will move into the swrn US, as an
upper level trough moves into the nwrn US. Meanwhile, sfc low pres
will be over ern CO, as a cold front nears the WY-CO border, by
late aftn. Ahead of this front, look for another mild day, with
readings mainly in the 65 to 70 degree range over nern CO. Will
keep in a chc of showers over the higher terrain with a slight chc
over nern CO.

Looking ahead to Sat night into Sun, a significant change will
occur, as the upper level trough will move from the nwrn US into
Colorado on Sun. In addition, a cold front will bring much colder
air to nrn CO as well. Overall, as the upper level trough moves
into the area, will see increasing mid level ascent and upslope
flow behind the cold front. Furthermore, the position of the
upper level jet, would place nrn CO in favored left front
quadrant. Thus, should see a gradual increase in precip Sat night
into Sun. Temps will be cold enough for snow, at lower elevations,
late Sat night into Sun. Depending on how things set up, there
will be some potential for heavy snow, over the mtns and
foothills, with accumulating snow over nern CO as well. Highs on
Sun will only be in the low to mid 30s across the plains.

For Sun night, NW flow aloft will develop with cross-sections
showing decreasing moisture and weakening upslope component. Thus
snow chances will decrease across the area. On Mon, another
disturbance embedded, in NW flow aloft, will move across the area
late in the aftn into Mon evening. In addition, another front
will move across as well, with upslope low level flow. As a
result, may see a period of steadier light snow in the mtns and
across portions of the plains. Temperatures will remain cold on
Mon with readings staying in the 30s across nern Co.

By Tue, NW flow aloft will continue with a decrease in moisture.
However, still will probably see a chc of snow showers in the mtns
with a slight chc across lower elevations.  Temperatures will be
mainly in the 40s over nern CO.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 925 AM MDT Thu Apr 9 2020

Have delayed the onset of lower ceilings until after 21z. Until
that time, VFR. After 21z prevailing ILS restrictions through mid
evening with bkn-ovc ceilings in the 050-060 ft range. best
chance of any showers will be from around 02-06z. North-northeast
winds 8-12 kts will transition to east-southeast around 00z, then
southerly by late evening.

&&

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

$$

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

NWS BOU Office Area Forecast Discussion