High Wind Watch 9, NWS Denver/Boulder, CO

550 
WWUS75 KBOU 281707
NPWBOU

URGENT - WEATHER MESSAGE
National Weather Service Denver/Boulder CO
1007 AM MST Thu Dec 28 2017

...HIGH WINDS FOR THE FRONT RANGE MOUNTAINS AND FOOTHILLS TONIGHT
THROUGH EARLY AFTERNOON FRIDAY...

.Strong and potentially damaging winds are expected to develop 
across portions of the Front Range Mountains and Foothills late 
tonight. Wind gusts in excess of 75 mph can be expected in wind
prone areas, with some gusts near 85 mph over places such as 
Berthoud Pass, the I-70 corridor near Georgetown, and higher 
ridges in the foothills west of Boulder. 

The winds may be quite variable and erratic at times, with light 
winds followed by sudden bursts of very strong and damaging winds.
That will also create hazardous and difficult driving conditions 
especially for drivers of high profile vehicles. Strong winds will
also cause areas of blowing snow and reduced visibilities in 
exposed areas. 

COZ033>036-290115-
/O.UPG.KBOU.HW.A.0009.171229T0700Z-171229T1900Z/
/O.NEW.KBOU.HW.W.0014.171229T0700Z-171229T2200Z/
South and East Jackson/Larimer/North and Northeast Grand/
Northwest Boulder Counties Above 9000 Feet-
South and Southeast Grand/West Central and Southwest Boulder/
Gilpin/Clear Creek/Summit/North and West Park Counties Above
9000 Feet-Larimer and Boulder Counties Between 6000 and 9000 Feet-
Jefferson and West Douglas Counties Above 6000 Feet/Gilpin/Clear
Creek/Northeast Park Counties Below 9000 Feet-
Including the cities of Cameron Pass, 
Laramie and Medicine Bow Mountains, Rabbit Ears Range, 
Rocky Mountain National Park, Willow Creek Pass, Berthoud Pass, 
Breckenridge, East Slopes Mosquito Range, 
East Slopes Southern Gore Range, Eisenhower Tunnel, Indian Peaks,
Kenosha Mountains, Mount Evans, Williams Fork Mountains, 
Winter Park, Estes Park, Glendevey, Nederland, Red Feather Lakes,
Bailey, Central City, Evergreen, Georgetown, Idaho Springs, 
and Westcreek
1007 AM MST Thu Dec 28 2017

...HIGH WIND WARNING IN EFFECT FROM MIDNIGHT TONIGHT TO 3 PM MST
FRIDAY...

The National Weather Service in Denver has issued a High Wind
Warning, which is in effect from midnight tonight to 3 PM MST
Friday. The High Wind Watch is no longer in effect. 

* TIMING...After some decrease in the winds today, strong winds
  will redevelop tonight. The strongest winds are expected to
  occur from just after midnight tonight through Friday morning. 
  Winds should slowly subside Friday afternoon. 

* WINDS...West winds 25 to 45 mph with gusts around 85 mph in 
  wind prone areas. 

* IMPACTS...Travel will be hazardous over high mountain passes 
  and along the Peak To Peak Highway due to very strong and 
  sudden crosswinds. Drivers of high profile vehicles should 
  avoid traveling I-70 west of Denver and Highway 40 over 
  Berthoud Pass. Power outages will also be possible from trees 
  blowing onto power lines. Areas of blowing snow will reduce 
  visibilities as well. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A High Wind Warning means a hazardous high wind event is expected
or occurring. Sustained wind speeds of at least 40 mph or gusts 
of 58 mph or more can lead to property damage.

&&

$$

Area Forecast Discussion
National Weather Service Denver/Boulder CO
913 PM MST Wed Dec 27 2017

.UPDATE...
Issued at 913 PM MST Wed Dec 27 2017

No changes to the forecast necessary at this time. Breezy
conditions continue in the mountains and at some valley locations
as strong northwest flow aloft continues. Moisture traed over the
northern mountains is producing only isolated snow shower
activity, but blowing snow is also occurring over the ridges. On
the plains, clouds will continue diminishing overnight. Another
breezy day looks to be in store for tomorrow up and down the Front
Range, as the pattern is similar to what was in place earlier
today.

&&

.SHORT TERM...(This evening through Thursday)
Issued at 218 PM MST Wed Dec 27 2017

Strong northwest flow pattern will continue across Northern
Colorado tonight and Thursday with a northwest to southeast
oriented strong jet over Wyoming and Nebraska. With this regime
expect continued strong and gusty winds over the mountains and
foothills at times. Wind gusts expected to be in the 40 to 65 mph
range in the mountains but will keep winds below wind high
criteria with only marginal surface gradients and weak marginal
mountain top stability. Low temperatures will be much warmer
in/near the foothills tonight with the downslope flow while low
lying areas on the plains will remain much colder. Continued mild
temperatures on Thursday with the downslope flow.

.LONG TERM...(Thursday night through Wednesday)
Issued at 218 PM MST Wed Dec 27 2017

For Thursday night into Friday the models maintain a strong NW flow
aloft with a persistent ridge over the western coast. A section of
the upper jet will move south bringing the more subsident portion of
the right exit region over the Northern Mountains starting around
midnight Friday and continuing into the afternoon. Model upper air
soundings show a stable layer developing near mountain top after
midnight Friday, relaxing and moving north in the morning and then
moving south once again by the late morning. A critical layer
develops that will help to bring increased winds down into the lower
foothills. Wind gust speeds up to 80 mph will be possible at
mountain top with 65-70 mph possible over the foothills by Friday
morning into the afternoon. Will hold off any highlights at this
time to allow for one more model run but expect a possible Watch for
winds in the mountains Friday. Conditions on the plains will be
breezy but below any criteria with temperatures increasing once
again into the upper 50s to low 60s given the warming downslope
winds helping to push out the evening cold air inversion.

Saturday and Sunday will see continued winds in the mountains, but
below watch criteria. Light snow will be possible with increasing
moisture ahead of the next incoming upper trough. The high pressure
center that was in place over the western coast will transition over
the Great Basin with an upper trough diving SE out of the Pacific NW
bringing cold air and precipitation to the region by midnight
Sunday. Mountains will continue to see snow Saturday night and
through Sunday. A cold front will drop south after midnight Sunday
bringing highs in the 20s and teens on the plains with a chance of
snow during the morning hours. Most areas on the plains will see
less than an inch with 2-4 inches for the mountains. Conditions will
dry out on the plains for the start of the week with temperatures
slowly rebounding back into the upper 30s to lower 40s.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 913 PM MST Wed Dec 27 2017

Drainage winds have set up at KDEN which are expected to continue
overnight. Gusty winds are also expected to continue at KBJC. No
aviation impacts are expected through tonight and tomorrow except
for the gusty winds on the west side of town.

&&

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

UPDATE...Dankers
SHORT TERM...Entrekin
LONG TERM...Bowen
AVIATION...Dankers

Hazardous Weather Outlook
National Weather Service Denver/Boulder CO
1015 AM MST Wed Dec 27 2017

COZ030>051-281715-
Jackson County Below 9000 Feet-
West Jackson and West Grand Counties Above 9000 Feet-
Grand and Summit Counties Below 9000 Feet-
South and East Jackson/Larimer/North and Northeast Grand/
Northwest Boulder Counties Above 9000 Feet-
South and Southeast Grand/West Central and Southwest Boulder/
Gilpin/Clear Creek/Summit/North and West Park Counties Above
9000 Feet-Larimer and Boulder Counties Between 6000 and 9000 Feet-
Jefferson and West Douglas Counties Above 6000 Feet/Gilpin/Clear
Creek/Northeast Park Counties Below 9000 Feet-
Central and Southeast Park County-
Larimer County Below 6000 Feet/Northwest Weld County-
Boulder And Jefferson Counties Below 6000 Feet/West Broomfield
County-
North Douglas County Below 6000 Feet/Denver/West Adams and
Arapahoe Counties/East Broomfield County-
Elbert/Central and East Douglas Counties Above 6000 Feet-
Northeast Weld County-Central and South Weld County-Morgan County-
Central and East Adams and Arapahoe Counties-
North and Northeast Elbert County Below 6000 Feet/North Lincoln
County-
Southeast Elbert County Below 6000 Feet/South Lincoln County-
Logan County-Washington County-Sedgwick County-Phillips County-
1015 AM MST Wed Dec 27 2017

This hazardous weather outlook is for northeast and north central
Colorado.

.DAY ONE...Today and Tonight

Expect very windy conditions through this evening in the
mountains and Front Range Foothills. Wind gusts from 40 to 70 mph
will be possible in the normal wind prone areas this afternoon and
evening. The strong winds will also create areas of blowing snow
and poor visibilities, especially along north and south oriented
roadways. Use extra caution on the Peak to Peak highway and along
Highway 93 between Golden and Boulder. The blowing snow may also
create icy and snowpacked spots on unsheltered roadways.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

Thursday and Friday, strong winds will develop in the mountains
and higher foothills. There will be a chance of some light snow,
mainly over the higher north and west facing slopes. Temperatures
over the northeast plains will warm into the 40s both days. It
will be a little cooler on Saturday, then much colder for Sunday
and Monday as an Arctic airmass backs into the Front Range from
the northeast. Over the weekend, it will be windy with areas of
snow in the high country, then a slight chance over the Interstate
25 Corridor and northeast plains, Saturday night into Sunday. For
next week light snow will continue to be possible for the
mountains while staying dry on the plains with temperatures around
normal.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed today or tonight.