Flash Flood Watch For Stillaguamish River


TONIGHT:

Puget Sound Forecast:

FLASH FLOOD WATCH for the North Fork Stillaguamish River is in effect for the area downstream of the dam — meaning flash flooding is possible but not certain or imminent — in case the debris dam fails.

FLOOD WARNING is in effect for the North Fork Stillaguamish River for the region upstream of the slide, in other words for the area where inundation is occurring now as water builds behind the slide.

Mostly cloudy with patchy fog. Lows in the 30s to low 40s. Winds: North 5-10 mph.

Coast Forecast: Mostly cloudy with a few showers. Lows in the 30s. Winds: West 10-15 mph, becoming easterly after midnight.

Mountain Forecast: Mostly cloudy skies. Snow Level near 4,000 feet decreasing to 3,000 feet. Light winds through the passes. Lows in the mid to upper 20s. 

Eastern Washington Forecast: A 20 percent chance of snow after 11pm. Mostly cloudy, with a low around 31. Southwest wind around 5 mph becoming calm in the evening.

TONIGHT:

Puget Sound Forecast: Patchy morning fog. We could see some freezing fog across the South Sound. Afternoon sunshine with a mix of sun and clouds. Afternoon highs in the mid to upper 50s. Winds: NE 5-10 mph.

Coast Forecast: Mostly sunny skies. Highs in the upper 40s to mid 50s. Winds: East 5-10 mph, becoming SW in the afternoon.

Mountain Forecast: Mostly sunny skies. Freezing Level: 4,500′. Pass Highs: 39-44. Light winds through the passes.

Eastern Washington Forecast: Mostly cloudy through mid morning, then becoming sunny, with a high near 50. Light and variable wind becoming west 5 to 10 mph in the afternoon.

EXTENDED OUTLOOK/DISCUSSION:

From our local NWS Forecast Office:

A landslide blocked the North Fork Stillaguamish River. Water is backing up behind the landslide. Some flooding is likely above the slide, east of Oso. There is also some possibility of flash flooding below the landslide if the blockage were to suddenly give way.

However, a recent model simulation by the Northwest River Forecast Center as well as calculations of scale suggest that catastrophic flash flooding is unlikely even if all the water backed up behind the landslide were to rapidly drain into the lower river.

Weekend Weather: A weak warm front moved across southern B.C., giving the Northwest Interior and parts of the North Coast a few showers.

High pressure will build for the end of our weekend. We’ll see afternoon sunshine and temperatures warming up as a result.

That means Sunday should be the brightest day of the weekend as high pressure builds with clearing skies and highs in the mid to upper 50′s. The sunshine holds into Monday with temps reaching the upper 50′s to low 60′s. Then rain returns Monday night into Tuesday through the end of next week.

Mary Lee / KING 5 Meteorologist

 




Source Article from http://www.king5.com/weather/seattle-area-forecast.html

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