Another Round of Active Weather on Tuesday

 FastCast—Tuesday, Oct. 25 to Thursday, Oct. 27:

Another system is ahead for Western Washington on Tuesday. This system will bring more rain than on Monday. Rain will start around noon, with showers lasting into the night. Expect 0.4-0.7 inches in the lowlands on Tuesday, with isolated spots getting less. There will be a rain shadow in the traditional area of the NE Olympic Peninsula. The coast and mountains will receive 1-3 inches of rain, and areas from Olympia southward have a chance to get over 0.8”. Additionally, Tuesday will be breezy, with winds gusting 20-30 mph around the area. Stronger winds, gusting up to 35-40 mph, are possible Tuesday afternoon/evening during frontal passage. Snow levels will again be around 4,000 feet, with 2-6 inches of new snow at the higher passes, and up to 12-24 inches on peaks over 8,000 feet. 2-12 inches of snow are also expected in the Olympics and Blue Mountains. Conditions will be drier on Wednesday, with highs in the low to mid 50s and lows in the low to mid 40s. There is a chance for a round of light rain on Wednesday night. Thursday will be dry in the morning, with the next round of rain arriving later in the day. Stay tuned!

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Another weather system will impact Western Washington on Tuesday. This system will bring more rain than Monday’s system, with another round of breezy conditions and mountain snow.

Let’s take a look at the rain forecast. The HRRR forecast is below, through 5 AM Wednesday.

The HRRR shows 0.3-0.6 inches of rain in the lowlands, with areas of 0.6-0.8 inches, mainly from Seattle southward and Everett to Arlington. The coast and mountains will receive 1-3 inches, and areas from Olympia southward will receive 0.75-1.1 inches.

Next, let’s compare this to the NAM model, also through 5 AM Wednesday.

The NAM shows a bit less rain in the lowlands, around 0.3-0.5 inches, with a potential Covergence Zone signature between Seattle and Everett showing up to 1.2 inches. The NAM brings 0.75-3 inches to the coast and mountains, but less (0.3-0.7 inches) from Olympia southward.

Another round of breezy conditions are also expected. Below is the HRRR forecast for 2 PM Tuesday.

The HRRR shows winds gusting 30-40 mph at peak in the Puget Sound area. This would be associated with frontal passage, which is expected at some time Tuesday afternoon or evening.

The NAM is a bit later and weaker with winds. The forecast at 5 PM Tuesday is below.

The NAM shows winds peaking around 5 PM, gusting 30-35 mph around the region. 

Although wind speeds aren’t very significant (30-40 mph), there is a slight chance of tree damage and power outages, so be prepared.

For the mountains, Tuesday’s system will bring another round of snow, mainly above 4,000 feet. The HRRR forecast through 5 AM Wednesday is below.

The HRRR is  more aggressive with snow, showing up to 8 inches at higher passes, with even higher amounts of 1-3 feet at the highest elevations (8,000+ feet).

The NAM model is less aggressive with snowfall on Tuesday, as seen below in the forecast through 5 AM Wednesday.

The NAM shows up to 6 inches at the higher passes and 1-2 feet of snow at 8,000+ feet. Both forecasts do show 2-12 inches of snow in the Olympic and Blue Mountains in addition to the Cascades.

Expect a break in the rain all day Wednesday and Thursday morning, before the next round of rain arrives midday Thursday. There is a chance for a round of rain overnight Wednesday. The extended signal is for above average precipitation through the beginning of November.

Below is the NWS Climate Prediction Center precipitation outlook for October 30 to November 3.

The CPC outlook shows a 60-70% probability of above average precipitation through the first few days of November. In short, active weather will continue into November, so stay tuned!