National Weather Service Forecast Discussion

000
FXUS65 KBOU 200323
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
923 PM MDT Tue Mar 19 2019

.UPDATE...
Issued at 918 PM MDT Tue Mar 19 2019

It has cleared out across the CWA at this time. I made appropriate
adjustment to the grids. Models are still indicate regular
drainage wind patterns to set up by 06Z.

&&

.SHORT TERM...(This evening through Wednesday)
Issued at 300 PM MDT Tue Mar 19 2019

Cold upper level Low spinning over western Nebraska is helping to
produce the convective cumulus field across the forecast area as
the trough axis passes over. Surface high pressure over Wyoming is
pushing gusty north-northwest winds across the plains, turning
northeasterly upslope near the Front Range foothills to create
weak rain/snow showers. It is pretty dry out there, so not too
much more than virga or a trace of snow, though temperatures in
the mid 40s will quickly melt it, if it was able to fall as snow.
Could see a little bit more over the foothills and ridge of the
Palmer Divide, but not more than an inch.  A few stronger showers
over the northeastern plains may cause some restrictions in
visibility with up to half an inch of snow. All this activity
should die down by sunset, with skies clearing from the northwest.
This will allow temperatures to cool quickly, with some very cold
spots expected in the high mountain valleys. The northwest winds
over the east plains will likely stay a bit breezy into the
evening hours before decreasing, but should see the normal cold
spots near Greeley and Limon.

Expect clear skies Wednesday and temperatures about 10 degrees
warmer for a nice spring day on the vernal equinox.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 345 PM MDT Tue Mar 19 2019

Meridional flow will setup across much of North America during the
long term period. A strong, digging trough over the northeast U.S.
will stall the flow across the western U.S. through the beginning
of the weekend. Consequently, a trough which will move onshore
over California tonight will slow as it moves over the four
corners region Thursday night. This system will bring a chance of
rain and snow showers to the mountains during the late afternoon
on Thursday through Saturday morning. Due to the higher snow
levels of up to 9000 feet at times, snowfall amounts will be on
the light side with the highest amounts in and near the mountains
of Summit County. A shortwave trough will rotate around the base
of the larger scale trough on Friday which will provide enough
forcing to create rain showers and a few thunderstorms across the
eastern plains. Models are indicating dew points getting into the
low 40s across the far eastern plains and with relatively cold mid
level air associated with the trough moving over the area, there
may be some instability and small amounts of CAPE. No severe
weather is expected but some people who live on the eastern plains
will be hearing thunder for the first time in 2019. Some models
indicate over an inch of rain could fall in a couple locations but
there is low confidence in that at the moment.

Westerly flow over the weekend will keep a chance of lingering
snow showers going in the mountains before the next system arrives
from the west. A high pressure system moving southward over the
northern plains early on Monday will shift the low level winds to
the northeast as colder air moves in. With the colder, upslope
flow at the surface and a trough moving overhead, rain and/or
snow showers will be possible across much of the CWA Sunday night
into Monday. There is low confidence in this system as models
disagree on its strength.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 918 PM MDT Tue Mar 19 2019

Models all indicate that, weak, normal drainage wind patterns
should kick in at DIA by midnight. There will be no ceiling
issues, and likely, no clouds at all overnight.

&&

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

$$

UPDATE.......RJK
SHORT TERM...Kriederman
LONG TERM....Danielson
AVIATION.....RJK

NWS BOU Office Area Forecast Discussion