Monday, February 20, 2012

Report Card, Part II

Boy, am I glad that my job isn't dependent upon accuracy. Yes, I have a unique job where I can be wrong one day and still have a job the next. By no means does that translate into intentional sloppy forecasting though. I don't use the "stereotype" as an excuse. I want to be right! Who doesn't? Last month I recorded my temperature and condition accuracy for just Portland. A recap for the month of January, a near-perfect conditions report was marred by a couple bad days that dropped my temperature accuracy to near-fail percentages. Well, I am bound to make it up in order to gain your trust in me as a forecaster.

Last week, I tracked my temperature accuracy for the entire state of Oregon (plus a few Washington cities too). In the weather center here at Fox 12, we forecast for 35 cities in our "viewing area" each day. That includes cities as far North as Kelso/Longview, Washington, as far East as Baker City and as far South as Albany. Most of the North and Central Oregon Coast are also accounted for. Here are the results keeping the same temperature criteria as my monthly reports (+/- 3 degrees for accurate temperature):

Monday, February 13: 24/35= 68%
Tuesday, 14: 30/35= 85%
Wednesday, 15: 25/35= 71%
Thursday, 16: 33/35= 94%
Friday, 17: 28/35= 80%

The final average comes out to 79% for the week. Looking back at reports, my two worst days (Mon, Wed) both had LIGHT wind forecasts. Clearly I have an issue with forecasting temperatures when winds don't become a factor. I would have figured it to be the other way around. My best day was Thursday, when I missed just two locations (Baker City was off by 7 degrees, and Mt. Hood Meadows was off by 5).

Which cities was I most accurate? Both Astoria and Newport had spot on accurate temperatures two out of the five days. I also hit the high temperature for a handful of other cities throughout the week. The most inaccurate forecasts have a common theme. Sandy, Welches, Mt. Hood Meadows and Timberline Lodge each had three missed temperatures. Clearly I have an issue forecasting the Cascade range. That is evident in the breakdown of accuracy by region:

Oregon Coast- 95% accuracy
Willamette Valley- 84%
Portland Metro- 85%
Mt. Hood area- 50% 
East of Cascades- 80%

Tough going in the Cascades. Temperatures vary greatly in a short area in the mountains which can make it difficult to accurately forecast temperatures. So I have an area I need to work on! But if you'd like a beach forecast, come talk to me!

Thursday, February 16, 2012

Tuesday's Quake

You may (or may not) have heard about the earthquake that occurred off the South Oregon coast this past Tuesday night. Not a lot of folks reported feeling it as it was situated roughly 160 miles west of Coos Bay. The 6.0 magnitude earthquake was unusually strong for an area that does have frequent tremors. So the fact that an earthquake occurred at this location is no reason to be alarmed. But was the strength of the quake something that coastal dwellers and Oregonians as a whole need to worry about? The short answer is: No.

Whenever an earthquake occurs under ocean waters, there is a period of time when we are on "pins and needles" awaiting word on if a Tsunami was generated or not. Luckily, no Tsunami was generated from Tuesday nights quake. The main reason was due to its location. The earthquake occurred along a fracture zone known as the Blanco Fracture Zone. This zone divides the very large Pacific Plate and the locally infamous Juan De Fuca Plate. The graphic below visually explains where the quake happened. The overall movement of the Pacific Plate is away from us. The Juan De Fuca Plate is shifting towards us. So when an earthquake occurs in the Blanco Fracture Zone, the overall movement of the Earth's plates is horizontal. This type of fracture zone is called a "Transform Boundary fault". The most famous of all fault lines in the United States is a transform boundary fault line, the San Andreas Fault. That fault is located in California and is the result of the Pacific Plate and North American Plate rubbing against each other.

Quake centered on the Blanco Fracture Zone
The reason no Tsunami was generated from the Blanco quake is because the overall movement of the plates were horizontal, not vertical. Most Tsunami are created as a result of uplift from one plate moving under another. The displacement of water results in Tsunami. So as long as earthquakes occur in the Blanco zone, the Oregon coast should be spared from Tsunami.

The scientific community, in addition to the media, have been warning the population of the United States west coast that the "Big One" is imminent. Many are predicting a 9.0 magnitude quake will strike again, just as it did on January 26th, 1700.  That quake occurred in a region known as the Cascadia Subduction Zone. Guess what? Oregon is a part of that zone. The Cascadia Subduction zone is an area where the Juan De Fuca Plate is literally sub-ducting, or folding underneath the North American Plate which we are anchored to. The 2011 Japan earthquake struck in a subduction zone where the Pacific Plate moves underneath the Okhotsk plate. As we all know, that resulted in a 9.0 earthquake and a deadly Tsunami that rushed over 6 miles inland and crossed the entire length of the Pacific Ocean!
The Cascadia Subduction Zone sits right off the Oregon coast

Subduction zones are infamous for large quakes and Tsunami. Records from Japan that date back to1700 indicate that a Tsunami reached the eastern shores of Japan as a result of the 9.0 earthquake just off of our coast! The Cascadia Subduction Zone is the region that scientists are looking at for the next big quake. Oregon's coast has been outfitted with extensive Tsunami alert systems and warning signs but there is no way to prevent the Tsunami. Let's hope that this doesn't happen in our lifetime.


Friday, February 3, 2012

January Report Card

A former teacher of mine always offered this word of advice:
"If I get the forecast wrong, I want to go down on my forecast. Not someone else's."
It isn't a profound, thought-invoking quote but it always resonated with me. Best to own up to my own mistakes than say "it's not my fault". I do my best to follow the "station" forecast, or the show-to-show forecast. It's tough though when you have three or four different meteorologists forecasting and each have their own style!
So, I begin my "resolution" to track and improve my forecasting skills this year. I haven't done this before, so I have no measuring stick to gauge improvement. But after completing 1/12th of the mission, there is definitely room for improvement and you will see why!

I will grade myself on two categories: accuracy of daily high temperatures and overall sky conditions/precipitation for that day.  Out of the 31 days in January, I had a forecast for 21 of them. Each meteorologist and "consumer" of a weather forecast has their own definition of accuracy. I've always used the +/- 3 degree range in order to consider a forecast temperature accurate. As for the sky conditions/precipitation department, that is more subjective. If you'd like to judge my forecasts under your own parameters, well, you'll just have to wake up early and tune into the show each morning! So without further delay, here is the January Report.

January temperature accuracy (+/- 3 degrees of actual high temperature) was only 52%! 11 out of 21 days were accurately forecasted. Of the 11 correct high temperatures, only two of them hit the high temperature exactly! Not very impressive. I missed the high temperature by an average of 5.5 degrees (technically 2 degrees when you factor in the plus-minus). There was a run of six consecutive forecast days with a missed high temperature. Those days spanned the middle of the month (Jan. 18-26). Coincidentally, those six forecast days were right after the valley snowfall days. More on those snow days in a bit. So ultimately, my temperature forecasts have a lot of room for improvement. This January was somewhat challenging in regards to high temperature forecasting. We had several weather systems that would lead to strange high temperatures that would occur in the evening or overnight hours. I'm not making excuses, it's just something that adds a little difficulty to projecting an accurate temperature.

The Report does have a bright side though. The sky conditions and precipitation forecast was near perfect. 20 of 21 days had accurate conditions! That works out to 95%. The lone botched day was on the 23rd. I had called for some morning fog and a shower followed by some clearing during the afternoon hours. Turns out, it did not rain that day and we never really cleared out either. The day will go down as mostly cloudy. I also missed the high temperature that day. But that was it! Nailed the 20 other forecast days!

During the month, Portland saw some where near 5" of snow. It all fell in a four day period from the 15th through the 18th. I will list out my exact forecast thoughts for each day below:
Sunday, 15th: Trace-1" of snow at the lowest levels. Snow showers tapering off in the afternoon. High 40.
We officially picked up a Trace of snow in Portland and the high temperature was 38 degrees.
Monday, 16th: Mainly dry morning with some snow showers in the afternoon. High 39.
Officially saw 0.08" snow during the afternoon. The high temperature was 38 degrees.
Tuesday, 17th: Rain/snow mix at times, sticking at about 1,000 feet. A south wind helps warm us. High 40.
We saw a rain/snow mix (I think it was more snow than rain) and that South wind (10-20) warmed us up to exactly 40 degrees!
Wednesday, 18th: Rain/snow turns to all rain by 7am in most metro area. A high of 48.
Snow only fell in the early morning hours, the rain began by 7am and lasted all day! The high was 53.

So the accuracy of my forecasts during this winter weather period was a pleasant surprise. Forecasting snow in Portland can be very challenging. The Report overall was interesting to see. There is plenty of room for improvement in the temperature area obviously. Conditions are my strength and I expect to see that continue. I hope the Report doesn't sway your opinion of where you get your forecast. But check back each month to see if and how I improve as the year continues!