Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 211216

Area Forecast Discussion
National Weather Service Grand Junction CO
516 AM MST Tue Feb 21 2017

.SHORT TERM...(Today through Thursday)
Issued at 516 AM MST Tue Feb 21 2017

The old "warm before the storm" phrase will be coming into play
today as we see an increase in west southwest flow across the
region. This will allow for a quick jump in temperatures with a
run into the 60s anticipated for the lower valleys this afternoon.
Bufkit soundings support the warmer than normal temperatures as
southwest winds mix down this afternoon. Gusts up to 25 mph
possible for the valleys this afternoon with slightly stronger
speeds up in the mountains. Some low cloud cover still trapped in
the valleys this morning, but should break out by mid-morning and
IR imagery showing little in the way of mid and high level cloud
cover at this time. So anticipated a period of sunny conditions
which will help get conditions mixing as sfc temps warm.

Cooler weather starts pushing in tonight as we await the next
round of wintry weather. Models in good agreement with sliding
energy, moisture and shot of cooler conditions into the northern
zones Wednesday and Wednesday night. The Eastern Uintah mountains
are in an interesting setup for this period as we see WSW flow
start off the day, but undercutting cold front slides through the
north slopes early Wednesday morning. This will swing surface
winds to the northwest and north and with moisture overrunning
colder air sliding in, should see a period of enhanced
precipitation. Soundings suggest an all snow event for the high
peaks and with a good 24 hours of potential moderate to heavy
snowfall, went ahead and issued a winter storm watch for over a
foot of new snow, favoring north facing slopes. The front will
eventually push across northwest Colorado late Wednesday afternoon
and Wednesday evening. This will get the northern mountains and
possibly the valleys in the snow game as well. Prolonged nature of
this events (starts Wednesday night and lingers through Friday
morning), will result in areas of heavy snowfall with amounts
generally in the 8 to 16 inch range. Lower elevations sites from
Vernal east to Steamboat will also see a rain flipping to snow
event with several inches of wet snow possible. Not as confident
in the lower elevations to issue any highlights just yet, but
potential is there.

The front will be hung up along the Bookcliffs and Flat Tops north
of Interstate 70 until Wednesday evening, before it finally makes
the jump and dives across the remainder of the forecast area. This
will usher in much colder weather by Thursday with daytime highs
dropping back below normal. May see snow levels down to 4k or so
by Thursday morning with snow showers possible on the lower valley
floors, including Grand Junction.

Overall, the pattern is looking active with windy and warm
conditions today replaced by cooler and wetter weather on
Wednesday, followed by cold and snow by Thursday.

.LONG TERM...(Thursday night through Monday)
Issued at 516 AM MST Tue Feb 21 2017

Dirty, flat ridging builds into the Central Rockies Friday and
Saturday with a break in the more widespread precipitation. Not
saying we will be shutdown, just slowed a bit as the west coast
loads up another round of rain and snow that arrives late in the
weekend. The GFS and ECMWF are not exactly in phase, but both
advertise continued unsettled weather as we close out the weekend
and march into the new work week. Confidence is still low on this
and will just keep mention of chance pops delivered with the
blended models. After starting the extending period off on the
cold side, some moderation is anticipated, but still below temps
experienced the past few days.


.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 516 AM MST Tue Feb 21 2017

Increasing winds will be the big story today as warmer weather
sweeps across the region. Winds aloft will be strengthening
throughout the day along and above ridges with some acceleration
of winds expected on east and northeast facing slopes. LLWS
possible at most sites late this afternoon and evening with gusts
up to 50 mph possible just above terminal sites. Winds eventually
reach the valley floors this afternoon and will break through sfc
inversions from time-to-time overnight. Isolated showers also
possible over the mountains which may result in brief mountain
obscuration and ILS cigs. Conditions deteriorate from west to east
on Wednesday as another moisture Pacific storm moves in.


CO...Winter Storm Watch from Wednesday evening through Friday morning
     for COZ003-004-013.

UT...Winter Storm Watch from Wednesday morning through Thursday
 afternoon for UTZ023.



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