Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 241748
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1137 AM MDT Sat Sep 24 2016

.UPDATE...
Issued at 1033 AM MDT Sat Sep 24 2016

Upper level trough of low pressure moving across Colorado is
producing isolated to numerous rain and snow showers in the high
country...most numerous in zone 31. The snow level is around 10
thousand feet with little accumulation expected. However...another
inch of snow will be possible through the day over favorable west
facing slopes. Cool temperatures are expected today with highs in
the 60s on the plains with only isolated showers possible mainly
along the Wyoming border. Only minor changes made to the grids.

&&

.SHORT TERM...(Today and tonight)
Issued at 215 AM MDT Sat Sep 24 2016

As upper low moves northeast today and tonight...we will
initially have southwest flow aloft to start the day...but by this
evening we will have northwest flow. This will allow the surface
high to build into northeast Colorado. Cold advection today and
tonight will allow scattered snow showers to continue over the
northern mountains. Will continue the advisory for zone 31...we
have had no reports in the area...but southeast of Laramie in
Wyoming 4 inches of snow has fallen. The precipitation has ended
on the plains...and downslope flow will keep it dry there today.

Temperatures today looked good...but with cold advection
tonight...lowered mins a few degrees closer to guidance
temperatures. koco is 18 degrees this early morning...and do not
expect it to be any warmer tonight.

.LONG TERM...(Sunday through Friday)
Issued at 215 AM MDT Sat Sep 24 2016

The elongated upper trough stretched north to south across the
state will push east Sunday with dry northerly flow left in its
wake. There may be a few light showers in the high mountains in
the early morning hours, but these should dissipate quickly. High
surface pressure will keep cool northeasterly flow into the state
to produce highs a few degrees cooler than today under mostly
clear skies.

The upper trough will leave a piece of energy that digs south
into Mexico while an upper ridge over the west coast pushes east
over the state Monday through Wednesday morning. This will bring dry
and warming conditions over the area. The leftover piece of energy
will retrograde back into California then get picked up in
southwesterly flow aloft and move into the Great Basin on
Wednesday. Both the GFS and ECMWF have slowed the easterly
movement of the weak upper low and the upper ridge axis over the
state, so I decreased the chance of precipitation on Wednesday.
The upper low will open into a wave and push northeast across
Wyoming, bringing enough moisture for scattered showers across the
area and slight chance of storms over the plains on Thursday.

Southwest flow aloft will continue Friday and Saturday as another
upper trough pushes in from the Pacific Northwest. This will bring
continued warm temperatures, around 10 degrees above average for
this time of year, and a slight chance of showers.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1033 AM MDT Sat Sep 24 2016

VFR conditions expected across local airports with winds shifting
to the northwest around 19z

&&

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

$$

UPDATE...jk
SHORT TERM...RTG
LONG TERM...Kriederman
AVIATION...jk


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