Monday, January 31, 2011

Forecast Wrap-Up

My apologies about the absence of a final post on Saturday. A few factors played into it: I was not at work in order to create my graphics and I actually did not have any Internet at my house on Saturday. Excuses, excuses I know. I may be looking for excuses for my forecast on Sunday as well! Things really didn't pan out the way I thought. In my last post I had determined with some confidence that Sunday would start mostly cloudy and eventually the clouds would part in the afternoon, remaining dry all day. But that didn't happen. One reason (excuse?) why...the models seemed to delay the rain!

In the few days leading up to Sunday, rain was forecasted for late Friday night and into Saturday. That didn't happen! Saturday was mostly dry But what did happen was a mostly dry, mostly cloudy Sunday with some rain that moved in late afternoon/early evening. Models tend lag or even accelerate some times and that can throw a wrench into the process of forecasting. The only way to maneuver around that is to know how certain models handle certain weather systems. I haven't been looking at the models long enough to pick up on the their tendencies. That will come with time. So really my conditions forecast was not all that far off except that rain ruined the accuracy of the forecast. I will be one of my toughest critics and give myself an X on the conditions but only by 0.03" (recorded amount of rain at the Portland International Airport).

My final forecast had a temperature high of 48 degrees. My forecast low was 38. Now, in order to give myself full marks for an accurate temperature forecast, I'd like to be with in +/- 3 degrees of the actual observed temperature. Sunday saw a high of (drum roll, please)...50 degrees! That high temperature occurred sometime between 2-3PM, typical for this time of year when our sun angle is rather low. During the summer we get our warmest temperatures of the day between 4-5PM. So my high temperature forecast was a success, missed it by 2 degrees. For the low, Sunday got down to...39 degrees. Missed it by one degree! Not to shabby.

If you would have asked me which I had more confidence in, my conditions forecast or my temperature forecast, I would have gone with the conditions. At least I got something right! I hope that this process allowed you to look into how I do my job and all the moving parts associated with it. I know weather forecasters, ones on TV especially, get a bad wrap. We are forecasting for an environment that is always changing. Portland and the Pacific Northwest as a whole is challenging to forecast fore given that most of our storm systems come off the Pacific ocean where current observations just aren't as abundant as if we lived in Kansas City. The Pacific ocean is dotted with some weather buoys but those don't help us nearly as much as observations from other cities. Places all across the central and eastern U.S. get to see what is approaching them and how an air mass headed their direction has been impacting the cities to their west. Also, the amount of model information out there is large. Many models and charts are at the forecasters fingertips and it can be a challenge to select which one is the correct one. All this information must be taken into account. It is definitely a challenge but someone has got to do it. I am glad I can!

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