Tuesday, September 16, 2014

World Weather Influences Your Weather

From an interview of Louis Uccellini, Director of the National Weather Service, regarding coordinating weather forecasting with other countries:
The weather-climate-water community is a global community. There’s a lot of interaction at various international conferences and the World Meteorological Organization. Many of the models we run are part of the multi-model ensembles that are run and shared among the international modeling centers.
From a day-to-day forecasting perspective, we need a global observing system to drive all our numerical models. Even though people may just be interested in their local forecast, that local forecast is imbedded within a global model, that’s driven by global observing systems and observations provided by countries all over the globe. For the forecasts themselves, we interact with European, U.K., and Canadian centers to share model information that influences our real time forecasts. So these partnerships are extremely important both from a research and an operational perspective, and part of the reason we’re seeing such a dramatic improvement in our extended range forecast is based on the partnerships.
In order to make a weather forecast for a specific area, we first need a forecast for the entire world. After we have a world forecast, we can run a finer scale model for a specific area.

For example, we start with the Global Forecast System (GFS),

Using the GFS as input, we can then run the North America Model (NAM), a model that only covers the United States (shown is the western states).

Using the NAM as input, you can then refine your forecast in a specific location with the Weather Research and Forecasting Model (WRF)

Friday, September 12, 2014

Wind Speeds at Spanish Fork

I've had my weather station in Spanish Fork for about 18 months now. Spanish Fork is famous for it's winds, so I thought it would be interesting to see a long term wind rose for my house. A wind rose shows the frequency of wind speed in a particular direction. Below is a wind rose for March 13, 2013 through September 11, 2014.

As shown below, 23% of the time wind blows from the south-south-east. 19% of the time from the south-east, and less frequently in the other directions. This is caused by out canyon wind (but also because there is a house on both sides of the station). Still, the down-canyon wind is much more frequent than an up-canyon wind. The colors indicate the wind speed of those winds. Very rarely do we have winds that blow more than 10 mph. Most of our winds are less than 6 mph.
I was also curious about how the timing of the down-canyon wind. When does it start and when does it stop. Below is plotted another wind rose, but the coordinates, instead of wind direction, is hour. The color still shows the wind speed. Notice the more warmer colors on the right side of the graph. From this we see the strong canyon winds blow during the morning hours. They are especially strong between 3:00 and 9:00. After 9:00 the frequency of strong winds drop. I usually tell people new to Spanish Fork that the wind usually stops around 10:30 in the morning, and this graph confirms that statement. After 10:30, winds above 5 mph are fairly infrequent. Also notice the bulge of blue around 19:00 (8:00 PM). Calm winds less than 1 mph are very common. This is during the transition between up-canyon and down-canyon wind flow. 

Bottom line from this quick analysis, when someone asks about the winds in Spanish Fork, say the canyon wind tends to end around 10:30 in the morning. The evenings are pleasant with little or no wind.

One thing we can learn from this is the ideal time to water your lawn. The best time would be in the evening around 9:00 PM. Since there is little to light wind, the water won't blow onto you sidewalk.

Good site for travel ideas and things to do in Utah

I'll post this so I don't forget about this website:

"But it's too early for snow!!!"

Here we are nearing the first day of fall, enjoying the leaves change colors...wait, why are the leaves white??

Tuesday, September 9, 2014

It's raining...a lot

Everyone is walking into school drenched.

My entire institute class is waiting or our teacher to arrive. Apparently there is an accident on Foothills Drive. The roads sure look wet there...

Our station at the Mountain Meteorology Lab at the University of Utah shows nearly half an inch of rain after 8:00 AM. And it's still raining! But it should pass by the time I have to walk across campus.

Lightning from the Mountain Met Lab...

And another lightning picture from WBB...