How a few miles can make or break a Pacific Northwest windstorm

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SEATTLE — Weather models are how forecasters interpret what will change over the course of time. The University of Washington produces weather models which excel in predicting Pacific Northwest weather.

Even with very good weather modeling, it is tricky work to observe and forecast a windstorm for many reasons, says Q13 News meteorologist Rebecca Stevenson.

Weather models

The photo on the left is a model output given Wednesday, March 8 — it shows a low pressure center of 1001 mb (which for the east coast may indicate a nor’easter, tropical storm, or Cat 1 hurricane). The center of the low is shown tracking across the southern tip of Vancouver Island & the Strait of Juan de Fuca. This location is ideal to create a rapid funnel of wind in-between the Olympic mountain range and Cascade mountain range.

The photo on the right is the model output given Thursday, March 9 — it shows low pressure center of 1002 mb, slightly weaker, and the location is placed much further north on central Vancouver Island. There is also a wider distance in between the isobars (the dark lines circling around).

It’s an exercise similar to the daily newspaper game of “list the differences.” Each difference indicates a change in weather or the weather forecast for the time.

In this case, the forecast shows weakening low pressure (or, low pressure that is rising) that comes close to a typical wind-storm path, but, each model shows the center of low pressure landing farther away and further north from Seattle.