The Pacific Index

Accuracy of meteorology relies on many factors

Scott Lepschat

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This February served as a strong reminder of how truly unpredictable the weather of the Pacific Northwest can be. The much-hyped “Snowpocalypse” early in February resulted in next to no snowfall on campus despite forecasters warning of four inches. The days following, which were also supposed to be snow-filled, instead were wet and rainy. Yet, at the end of the month, snow fell on two mornings and closed campus on February 27th.  

There was certainly a rush to blame forecasters for not seeing what occurred in advance, but meteorology is not always a perfect science. Last month served as a reminder that even with modern equipment, forecast models are less reliable when it comes to long-term periods. Weather projections rely on assumptions. Variables such as temperature, wind speed, cloud cover all combine to make any clear, direct projection less likely to be accurate beyond a day or two. This is coupled with various physical features in Northwest Oregon that can affect weather patterns, such as the West Hills, Coast Range, and Columbia River Gorge. Meteorologists must interpret dozens of models that forecast beyond a few days. These display a wide variety of potential outcomes as they rely on previous levels of predicted variables and project accordingly. When there is a small error, such as if it is not quite as cold as projected, over time that cascades to make projections further out less accurate.

This is exactly what happened with the Snowpocalypse. Models expected that Forest Grove and Hillsboro would see temperatures below freezing earlier than actually occurred. The result was less snow in this area, while other parts of the Portland Metro saw quite significant accumulations. The snow event at the end of the month however, affected the west end of the metro area far stronger than either Portland itself or some of the areas that got snow earlier.

Forecasting is a tricky business and meteorologists should not castigated for the weather not panning out exactly as they said. They are forced to interpret sometimes widely divergent projections and make a judgement as to what they believe will occur. Ultimately, it is better for them to sound the alarm and warn residents when snow is possible than to be complacent and allow for everyone to be caught off-guard. So no, don’t blame the meteorologists. Meteorology cannot yet make projections with the degree of precision some people demand.

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Accuracy of meteorology relies on many factors