Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 111557

Area Forecast Discussion
National Weather Service Denver/Boulder CO
957 AM MDT Sun Mar 11 2018

Issued at 957 AM MDT Sun Mar 11 2018

High pressure continues to bring lots of sunshine and lighter
winds to the forecast area. Cirrus shield to our southwest is
eroding nicely as it enters the upper level ridge axis. Forecast
is on track.


.SHORT TERM...(Today and tonight)
Issued at 400 AM MDT Sun Mar 11 2018

Short wave ridging will move across Colorado today. This will
bring mostly sunny skies and light winds. Airmass behind
yesterday`s cold front will be a little cooler with highs
slightly below normal. However, mostly sunny skies and light
winds will make for a pleasant early spring day.

A short wave trough moves into Wyoming tonight. Cloud cover is
expected to increase over the northern mountains late tonight
with the approach of this system. It will be a cool night with
readings in the upper teens and lower 20s.

.LONG TERM...(Monday through Saturday)
Issued at 400 AM MDT Sun Mar 11 2018

The latest model run continues to show a weak shortwave and
associated 65-75kt speed max swinging sewrd over nern CO during
the afternoon and evening hours on Monday. The right entrance
region of this jet is fcst to pass over the CWA sometime between
21z-01z. Moisture accompanying this system appears shallow and
largely confined to the 700-500mb layer, with the underlying layer
remaining fairly dry. Although model cross sections indicate some
moistening of the boundary layer east of the mtns during the
evening hours with an east-southeast low-level flow. For now,
will keep a chance of snow showers in the mountains and foothills
during the above mentioned period, and add a slight chance of
light rain showers along the base of the foothills and Palmer
Divide around the time of the passing speed max. Furthermore,
cloud cover and slight cooling aloft should hold temps down some
on Monday, though max temps should manage to warm 4-8 degs f
above readings predicted today.

For Tuesday and Wednesday, a tall upper level ridge is progged to
pass over the Rocky Mtn region bringing with it much warmer and
drier air. Lighter winds will also accompany this system.
Modest warming is expected on Tuesday as the flow aloft will
still be northwesterly. By Wednesday, should see temperatures
spike up as the ridge axis passes overhead, with upper 60s and
lower 70s for highs on the plains. Temp guidance has been creeping
up with each model run, and with the anticipated lack of cloud
cover and light winds, Wednesday could end up being the warmest
day of the week.

Looking ahead to the end of the week, models remain in good
agreement with a longwave trough off the Pacific West Coast on
Thursday and the periodic ejection of weak shortwaves from the
base of this trough. Predicting when and where these pertabations
will track, remains the biggest challenge at this time. Models
offer as variety of possibilities. Large scale features on the GFS
and ECMWF appear reasonably similar, while the Canadian model
appears faster and farther south with them. GFS and EC show the
deepening West Coast trough moving inland Friday into Saturday
which places Colorado under a unusually strong and fairly dry
southwest flow. The Canadian, on the other hand, shows the trough
moving over the western CONUS in pieces, with the principle
business end of the trough tracking east across the Desert
Southwest on Saturday. What does all this mean for north central
and northeast Colorado? Well in general terms, cooler
temperatures, an increase in cloud cover, and the possibility of
measurable snowfall for the high country sometime Friday through
Sunday, and a chance of showers at lower elevations by Saturday,
or possibly not until Sunday. Difficult to say. For now, will go
with this as I`m sure the models will undergo many more iterations
during the next few days.


.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 957 AM MDT Sun Mar 11 2018

VFR conditions will prevail through tonight under mostly clear
skies. Winds will be at or less than 10 knots, and conform to
normal diurnal wind patterns.




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