Model Score

Today on Facebook I saw once again a criticism of meteorologist: "Chance of showers today, they said....."

Yeah, it's an old joke (sometimes appropriate, but many times not).

In my environmental stats class we looked at how well some weather models perform. In the past several decades we have seen much improvement in weather forecasting capabilities (positive trend in graphs shown below). There is an annual variability in the forecast skill. Forecasts tend to be better in the winter months and worse in the summer months. We can also see that the GFS, EC, and UK models trend together with the EC model being the best overall. The CDAS is the worst of the four. 

Below shows how well several models have performed at weather forecasting in the last month. A value of 1 would be a perfect forecast. First, notice that none of the models are perfect. Second, notice that no one model is more right than others all the time. That's why it's important to consider all models when making a forecast. This graphic can be found here.

Granted, these errors are based on 500 millibar heights, which is perhaps the easiest variable to forecasts. The error trends between models for precipitation or wind speed would look quite different and likely have much less forecast skill.

Fireball in the Sky

Source: KSL.com

Source: KSL.com

A bright streak of light crossed over Utah's sky late last night around 11:00 pm. I missed it because I was asleep. However, this reminds of me a time when my brother, grandpa, and I were laying on the grass in our backyard probably ten years ago and saw a similar burning fireball. If was loud and the streak nearly crossed the entire sky before fading.

The burning ball of light last night was caused by the remains of a Chinese rocket Yaogan Weixing-26 launched last December. 



The KSL story can be found here.


A list of sightings can be found at the AMS Fireball report page.

If you ever see a fireball you can report the sighting here.

Another Downslope Wind Event

It's another windy day along the northern end of the Wasatch Front. These strong easterly winds often occur when we have a low pressure set up in southern Utah with cold, stable air to our north east. Winds blow cyclonicly (counter-clockwise) around the low pressure center which pulls the cold stable air over the Wasatch Mountains. Since the air is cold and stable, when it passes over the mountains or funnels through the canyons it suddenly sinks and creates the strong winds.

MesoWest weather stations shows that the winds are strongest near the canyons. It was a blustery walk up to campus this morning.

University of Utah: Gusts nearly 50 mph at the Natural History Museum

Bountiful Bench

Hill Air Force Base and Weber Canyon

Brigham City

 The wind advisory is in affect until noon. Winds are expected to weaken in the late morning and early afternoon.

...HIGH WIND WARNING REMAINS IN EFFECT UNTIL 11 AM MST THIS
 MORNING...
 
 * AFFECTED AREA...THE WASATCH FRONT FROM BRIGHAM CITY SOUTH
   THROUGH THE NORTHEASTERN PORTION OF THE SALT LAKE VALLEY.
 
 * WINDS...EAST WINDS 25 TO 35 MPH WITH GUSTS APPROACHING 60 MPH
   NEAR THE MOUTHS OF THE CANYONS.
 
 * TIMING...STRONG EASTERLY CANYON WINDS WILL CONTINUE THROUGH THIS
   MORNING. THESE WINDS WILL GRADUALLY DIMINISHING DURING THE LATE
   MORNING AND AFTERNOON HOURS.
 
 * IMPACTS...STRONG CROSSWINDS WILL IMPACT TRAVEL ALONG THE I-15
   AND US 89 CORRIDORS...ESPECIALLY THROUGH WEBER AND DAVIS
   COUNTIES...AND ALONG THE EAST SIDE BELT OF I-215 IN EASTERN SALT
   LAKE COUNTY. HIGH PROFILE AND LIGHT WEIGHT VEHICLES SHOULD USE
   EXTREME CAUTION WHILE TRAVELING THROUGH THIS AREA. WIND
   SENSITIVE OPERATIONS WILL BE AFFECTED.

While the ozone pollution isn't in the unhealthy range, it is interesting that ozone concentration has stayed flat during this wind event

It appears the background levels of ozone last throughout the night since the NOx titration of ozone is not occurring in the cities during the wind events.

Not much Rain today

On my drive to school this morning I had to turn my windshield wipers on a few times as I crossed the point of the mountain. Looking out across the rest of the valley I could see it was trying to rain just about everywhere else, but it was nothing but virga. Virga is a result of rain evaporating before it hits the ground, like in this picture...

The radar echos, however, make it look like the rain was widespread and heavy. Nope, most of this stuff was evaporating.

Our camera at SunCrest shows a quick set set of snow blowing over. 

The rest of the day has been but quite mild and cloudy with popcorn cumulus sprouting all around and stratus moving in this evening.

Lots of Snow in the Eastern U.S.

NASA's Terra satellite shows the widespread snow cover in the east. Today's been really cold.

Source: NASA

Source: preview.weather.gov/edd