12:43 PM Fri, Jan 05, 2007 | Permalink
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Snow lovers in Portland are like Charlie Brown trying to kick a field goal: Lucy keeps pulling the ball away at the last second and we end up on lying in the mud. Time and again, computer forecasts show promising signs of Arctic air invading the Northwest, with moisture coming in off the Pacific for that magical snow making combination that so often eludes us. And then, as we get closer to the advertised event, the models back off on the Arctic intrusion and become more accurate, and the cold air stays mainly to our east. We get a chilly east wind for a day or two and maybe a brief burst of valley snow. Disappointment once again, but why?
It comes down to basic climatology and geography, and Portland snow storms have to buck both to really have a chance. Weaher systems in our part of the world in general move from west to east, with a lot of north south variation, but the overall trend is to the east. The air masses that originate to our west, over the Pacific, are generally too warm to produce sea level snow. So we look north for Arctic air. As those air masses form and move south, they also tend to move east because of the basic nature of weather patterns as noted above. That's where we fight climatology. But there are also some major geographic barriers, namely the Rockies and to a lesser extent the Cascades, that literally act as a road block to the southward moving Arctic air and prevent it from expanding west to the Pacific Northwest coast. That's where we fight geography. And even when Arctic air manages to make it west of the Cascades, we still need moisture to make snow. That typically comes from the west, which also means the warmer Pacific air is returning. So everything has to fall in place just right, and against the natural tendency of our weather patterns, to produce a big Willamette Valley snow storm. It does happen, however, and it will happen again, so snow lovers don't lose hope!
Matt Zaffino
KGW Chief Meteorologist
I have a 9 1/2 year old grandson who since he was 4 has said he wants to be a weatherman. He wa5ches the weather every news hour that he is home. Is there anyway that he could meet you and come to the station and see how you do the weather?
My phone number is 503-648-0278. Address is 3318 E. Main
Hillsboro, Oregon 97123
Thank you very much
Diane Lee