Wet Weather Returns to Western Washington

 FastCast--Thursday, April 25 to Monday, April 29:

After a relatively dry month, by Seattle standards, a rainy pattern will return to Western Washington to round out April. Thursday will be the rainiest day of the pattern, with 0.4-0.8" of rain across the lowlands. A chance of showers will persist every day through at least Monday, and likely beyond. Conditions will be overcast, except for some potential sunbreaks on Monday. High temperatures will be below average, with highs on Thursday only reaching the low to mid 50s, and remaining in the mid to upper 50s through Monday. Wetter and cloudier conditions will keep lows in the upper 40s through Sunday, decreasing to the upper 30s to low 40s by Monday. Despite a wetter pattern, snow will remain mostly above 5,000 feet, with a trace to 1" of snow possible at the higher passes through early next week.

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Continue reading the full blog below!

A wet pattern is returning to Western Washington after a relatively dry past few weeks. Let's take a look at the forecast!

We'll start with the European model forecast for rain through midday Friday.

This forecast shows areas from Seattle south and Mount Vernon north getting 0.5-0.8" of rain by midday Friday, with a rain shadow from Seattle to Mount Vernon, and west along the Strait, where 0.3-0.5" of rain is possible. The coast and mountains will receive 1-2" of rain, most in the Olympic Mountains. Parts of Eastern Washington, mainly mountainous areas, will get 0.1-0.3" of rain.

Let's compare this forecast to the high-resolution NWS NBM forecast, also showing total rain through midday Friday.

This forecast largely agrees with the European model, except it shows a lesser rain shadow, which is mainly confined to areas west of Whidbey Island. This forecast shows 0.5-0.9" of rain in the lowlands, with 1-2" on the coast, and up to 3.75" in the mountains, most in the Olympics and Southern Cascades.

What about mountain snow? Below is the European model forecast for total snow through midday Friday.

As we get later in spring, it gets harder to get significant snowfall. The winners for snow will be the volcanic peaks, with Paradise and Mount Baker being the only recreation areas to get some snow, as the snow level remains around 5,000 feet.

You'll definitely notice that temperatures will be on the cooler side, as seen below in the NWS NBM forecast for Thursday's highs.

This forecast shows highs on Thursday only reaching the low to mid 50s west of the Cascades. Eastern Washington will reach the low to mid 60s. Expect temperatures across the state to warm a few degrees on Friday.

We'll end this blog by taking a look at the extended outlooks for the end of April and first few days of May. These outlooks are from the NWS Climate Prediction Center (CPC). 

First, the CPC temperature outlook.

For April 30-May 4, this outlook shows a 50-70% probability of below-average temperatures in Washington, highest for Western Washington.

Next, let's see how the temperature and precipitation outlooks correlate.

This outlook shows a 40-50% probability of above-average precipitation for Washington through the first week of May. 

Stay tuned for more information, and enjoy the rainy weather while we have it! All the rain counts toward more water for the summer!