Spanish Fork Wind Storm Summary

Yesterday's wind storm is summarized in the cart below. Wind gusts ranged from 25 and 30 mph before noon.

These gusts are nothin' compared to what they experienced in Davis County

In comparison, a category one hurricane has sustained winds of 74 mph.

southern snow

That cold wind from yesterday is moving south and will bring snow to southern Utah and Arizona. Flagstaff is expecting a high of 28 degrees F with up to six inches of snow.

NAM Forecasts: Wednesday 8:00 PM MST
Source: Weather.utah.edu

A Blustery Day

source: KSL.com

The large scale, or synoptic, weather conditions have set up another downslope wind storm for northern Utah. If you live north of Salt Lake City you're pretty familiar with these types of wind storms. These events cause freeway closures, blow over trampolines, and carry your trampoline down the block. These storms occur when a mass of cold air comes into Utah from Wyoming and "waterfalls" down the Wasatch Mountains causing a cold, strong wind. If you live in Utah county you can thank the Uintah mountains for the lighter winds.

Still, winds in Spanish Fork are stronger today than normal on this downslope windstorm type of day. The ten minute averaged winds are around 15 mph and gusts nearing 30 mph.

However, winds are much stronger further north. At the University of Utah, on top of the William Browning Building, ten minute average wind speeds are 25 mph with stronger winds at the mouth of Red Butte Canyon. Gusts are over 55 mph.

And the temperature  just keeps dropping, currently 10 degrees F. That's a cold wind. The wind chill makes it feel like -12 degrees F.

And a little further north, in Farmington, some of the strongest winds have been reported. This station currently is reporting sustained winds of 44 mph with gusts up to 77 mph! Surrounding stations measure similar wind speeds and gusts.

 I remember being told that Lagoon's ferris wheel, the Sky Ride, was built to withstand a hurricane. We don't have hurricanes in Utah (obviously), but we definitely get hurricane strength winds.

Clearfield Traffic Camera with blowing snow.
source: UDOT.utah.gov

source: KSL.com

I-15 is closed to semis due to the high winds and tipped trailers. 

These high winds will last most of the day and into the night. By this evening you may have new snow to shovel while you're neighbor will be lucky enough to have no more snow in their yard. It all depends on where those snow drifts settle.

From the National Weather Service:

High Wind Warning

URGENT - WEATHER MESSAGE
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
202 AM MST TUE DEC 30 2014

UTZ002-302300-
/O.CON.KSLC.HW.W.0011.000000T0000Z-141231T1100Z/
NORTHERN WASATCH FRONT-
INCLUDING THE CITIES OF...BRIGHAM CITY...OGDEN...BOUNTIFUL
202 AM MST TUE DEC 30 2014

...HIGH WIND WARNING REMAINS IN EFFECT UNTIL 4 AM MST WEDNESDAY...

* AFFECTED AREA...THE NORTHERN WASATCH FRONT FROM BRIGHAM CITY
  SOUTHWARD TO NORTH SALT LAKE. THE STRONGEST WINDS ARE OCCURRING
  BETWEEN LAYTON AND BOUNTIFUL...INCLUDING FARMINGTON AND
  CENTERVILLE.

* WINDS...EAST WINDS GUSTING IN EXCESS OF 60 MPH...WITH LOCAL
  GUSTS IN EXCESS OF 75 MPH.

* TIMING...THE STRONGEST WINDS ARE FORECAST TO OCCUR THIS
  MORNING...PEAKING MID TO LATE MORNING...BEFORE GRADUALLY
  DIMINISHING THROUGH TONIGHT.

* IMPACTS...THIS IS A POTENTIALLY DANGEROUS SITUATION. STRONG
  CROSSWINDS ARE OCCURRING ALONG I-15...HIGHWAY 89 AND THE LEGACY
  PARKWAY THROUGH DAVIS AND WEBER COUNTIES WHICH WILL CREATE
  HAZARDOUS TRAVEL FOR HIGH PROFILE VEHICLES AND THOSE WITH
  TRAILERS. SIGNIFICANT BLOWING AND DRIFTING OF SNOW WILL ALSO
  CAUSE GREATLY REDUCED VISIBILITY AND SLICK ROADWAYS. VERY COLD
  WIND CHILLS CAN ALSO BE EXPECTED...WITH READINGS OF 20 TO 25
  DEGREES BELOW ZERO. POWER OUTAGES ARE POSSIBLE... GIVEN THE VERY
  COLD TEMPERATURES HAVE A CONTINGENCY PLAN IN THE EVENT OF A LOSS
  OF HEAT. LOOSE OBJECTS SUCH AS TRASH CANS... TRAMPOLINES AND
  LAWN ORNAMENTS WILL BECOME AIRBORNE RESULTING IN POTENTIAL
  PROPERTY DAMAGE. WIND SENSITIVE OPERATIONS WILL BE AFFECTED.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A HIGH WIND WARNING MEANS A HAZARDOUS HIGH WIND EVENT IS EXPECTED
OR IS OCCURRING. SUSTAINED WIND SPEEDS OF AT LEAST 40 MPH OR
GUSTS OF 58 MPH OR MORE CAN LEAD TO PROPERTY DAMAGE. VEHICLES...
ESPECIALLY HIGH PROFILE VEHICLES...CAN BE DIFFICULT TO CONTROL AT
TIMES IN HIGH WINDS. MOTORISTS SHOULD TAKE EXTRA CAUTION...
ESPECIALLY WHILE CROSSING BRIDGES...OVERPASSES AND UNSHELTERED
AREAS.

Also be aware of the elevated avalanche danger today:

THIS AVALANCHE WARNING IS FOR CANYON MOUTHS AND FOOTHILLS OF
CACHE...DAVIS...WEBER AND EASTERN SALT LAKE COUNTIES. STRONG WIND
WILL CREATE POTENTIALLY DANGEROUS WIND SLAB AVALANCHE CONDITIONS
IN LOW ELEVATION AREAS WHERE PEOPLE DO NOT NORMALLY SEE
AVALANCHES. AVALANCHE DANGER IS EXPECTED TO INCREASE TODAY AND
CONTINUE INTO WEDNESDAY.

THIS WARNING DOES NOT INCLUDE SKI AREAS OR HIGHWAYS WHERE
AVALANCHE CONTROL IS NORMALLY DONE.

Skiing :) New Snow and Rime

Before Christmas I went on a ski trip with my cousins to Brundage Mountain. Brundage is a ski resort near McCall, Idaho. They claim to have the "Best Snow in Idaho." The days we skied didn't have the best snow, but I'd say the view is one of the best!

The day before skiing the mountain received about of foot of new snow. After the first ride up the Bluebird lift it was apparent there was a lot more weather going on the night before than just snow. Everything at the top of the mountain was covered in thick rime. The wind sensor on top of the ski patrol hut was surely not working properly.

Ski Patrol at the top of the mountain.

Rime is caused when the temperatures are below freezing, but the cloud droplets aren't quite frozen--the cloud is still liquid. Water doesn't necessarily freeze at 0 degrees Celsius. It needs something to freeze onto. For example, water will freeze onto dust particles (I suppose this is why as a kid I was always told that snow is dirty when it falls from the sky).

Liquid cloud droplets below freezing are called supercooled. Riming occurs when supercooled droplets hit something they can freeze onto. The droplets then freeze on contact. From all the riming on all the trees, chairlifts, towers, and buildings, it is apparent that the clouds last night were supercooled.

A general wind direction can also be inferred based on the side of the object the rime is located. You can see in the picture below that most of the rime is on one side of the post. That is the direction the wind was blowing. The wind blew the supercooled droplets onto one side of the post.

Also notice the detail in the rime. This isn't the same thing as snow. It's not made of flakes. Instead, it looks a lot like the frost build up you would see in an old freezer.
Snow flakes can also be rimed. Since the top parts of a cloud are much colder than the bottom, ice crystals are common at the top of a cloud while the bottom of the cloud can be made of supercooled droplets. As the snowflake falls through the cloud it collides with the supercooled droplets and we get graupel! Those soft, hail-like snow pellets.

Below are pictures of snow flakes taken by a multi-angle snow flake camera. On the left is a normal snowflake, the middle is a flake that is lightly covered in rime, and the right picture is a flake completely covered by rime, otherwise known as graupel.

More pictures of skiing:

On the way home from Idaho my cousin and I had to rent a car in Boise to drive to Salt Lake. We took rode the Frontrunner the rest of the way home. We looked like a pair of ski bums carrying all our gear and Christmas packages.

And just a few days after Christmas I took my younger brothers skiing at Sundance. It was the first time for two of them, and they caught on quick. I'll have to take them up again. Hopefully we'll have better snow this week. It was a really icy. 

This is what it looked like on the University of Utah campus Monday morning. Probably wont get much more between now and next ski trip.

Snow today, cold and windy tomorrow

It finally looks like winter with some snow on the ground, and tomorrow it will start to feel like winter. Today we'll have a high in the low 30s, tomorrow the high will be in the low 20s! 

The fridged trough stretching over Utah will bring cold Candian air to our state until after the new year.

12 km NAM Forecast, Tuesday 11:00 AM
Source: weather.utah.edu

These synoptic conditions are the recipe for another downslope windstorm for areas north of Salt Lake. The high resolution NAM forecast shows sustained winds up to 15 meters per second (~30 MPH)

4 km NAM forecast, Tuesday 11:00 AM
Source: weather.utah.edu

The National Weather Service has issued a wind advisory for December 30-31

Source: NWS