Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 211042

Area Forecast Discussion
National Weather Service Denver/Boulder CO
442 AM MDT Wed Mar 21 2018

.SHORT TERM...(Today and tonight)
Issued at 442 AM MDT Wed Mar 21 2018

Water vapor and IR imagery show a flat upper level ridge building
over the Central Rockies. Warm advection continues, and snow has
all but ended in the mountains earlier this morning. However,
there is another batch of mid/upper level moisture now moving into
Utah per current satellite imagery and radars, so expect a few
snow showers to move back into the mountains later this morning
into early afternoon before dissipating again. Wouldn`t expect
more than an inch of snow in the far northern mountains as
orographics are poor (southwest flow aloft), and airmass is
quite stable (lapse rates 4-5C/km).

On the plains, the mid/upper level clouds will thicken later this
morning into the afternoon but there`s no threat of precipitation.
High temperatures will respond to the warm advection, although
cloud deck will likely limit highs to around 60F for most of the
plains. With the ridging aloft and weak surface gradient, winds
will be lighter today.

.LONG TERM...(Thursday through Tuesday)
Issued at 442 AM MDT Wed Mar 21 2018

Medium range forecast models show a gradual progression from upper
ridging over Colorado to southwesterly flow aloft and then an
upper low over the southwestern U.S. over the next seven days. The
upper ridging is forecast to continue over the state from Thursday
through Saturday with a quick passage of a short wave disturbance
Friday afternoon and evening. The upper ridging with warm
temperatures aloft will be accompanied by low pressure at the
surface that will draw in warm air from Texas and western
Oklahoma. High temperatures on the plains will be well into the
70s on both Thursday and Friday. In the mountains, moisture will
be moving into the region, downstream from the moist upper trough
producing weather problems over southern California. The
combination of southwesterly flow and subtropical origin of the
moisture will cause snow levels in the mountains to be quite high
through Thursday night and only slightly lower on Friday. Shower
activity over the mountains Friday morning will decrease through
the day as the upper ridge rebuilds over the mountains.

Saturday will be a little cooler than Friday, but dry over the
mountains and onto the plains as the upper ridge begins moving
eastward. Come Sunday and Monday, an upper trough off the Pacific
Northwest coast will move ashore and begin dropping southward as
it intensifies. This will spread moist southwesterly flow aloft
over Colorado. The airmass will be cooler by that time which will
result in lower mountain snow levels than Friday. At some point on
Monday, a cold front is expected to move over northeast Colorado
which will help to moisten the airmass over the plains. Aloft, the
upper low will be over Utah Monday evening with deep southerly
flow over Colorado. This should spread precipitation out over
northeast Colorado Monday night. After midnight, the airmas could
be cool enough for snow to develop on the plains. The upper low is
forecast to drop further south into northwest Mexico next
Wednesday which will keep an unsettled southerly flow pattern in
place over Colorado. Mountain areas should continue to see some
light snow, but it is hard to say how much precipitation will
continue on the plains.

All in all, the snowfall amounts over the mountains does not look
too threatening at this point, even though several days of the
forecast period will see light rain or snow. Plains locations
should only see precipitation Monday night.

Thursday and Friday`s warm temperatures on the plains will
produce low humidities, especially over southern Lincoln County,
which could elevate Fire Danger levels. However, only modest
westerly winds are expected, so no fire weather highlights are
expected at this time.


.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 442 AM MDT Wed Mar 21 2018

VFR conditions will persist with only scattered to broken clouds
above 9000 feet. Southerly winds around 10 knots should persist
through most of this period, with a more easterly component
expected 19Z-01Z.




SHORT TERM...Barjenbruch
LONG TERM...Dankers
AVIATION...Barjenbruch is the U.S. government's official web portal to all federal, state and local government web resources and services.