A wetter system will impact the area by Saturday morning,
bringing along copious amounts of moisture, breezy conditions, and
more mountain snow. Winds look to definitely be breezy throughout
the coast and the interior by Saturday morning, and will need to
be monitored for a potential wind advisory. Snow levels will
slowly rise to around 2500 to 3000 feet throughout Saturday
evening. Even with snow levels being a touch higher, heavy
mountain snow will still continue, and moderate to heavy rain can
be expected elsewhere. This timeframe onward is when hydrologic
concerns will heightened, with rising rivers and snowmelt runoff,
because precipitation will compound on each other in the next
several days.
An atmospheric river will push into Western Washington early on
Sunday, bringing widespread moderate rainfall throughout the area,
with the heaviest rain likely in the Olympic basins, along with
the Cascades. Another round of breezy winds are likely as well,
especially areas near the water (coastal locations and areas
around Whidbey Island northward). Snow levels will rise to around
5500 to 6000 feet by Sunday afternoon, limiting snow to the higher
elevations in the mountains. With snow levels rising during this
time and relatively warm rain falling on fresh snow, hydrologic
impacts can be expected, especially with the continuous swath of
moisture, this will make river flooding more likely along with
snowmelt runoff in the mountains. See the hydro section down below
for more details.
.LONG TERM /MONDAY THROUGH THURSDAY/...A second, stronger
atmospheric river will impact W WA by Monday morning and last into
Tuesday. Ensemble model guidance depicts a strong plume of
southwesterly Pacific moisture being aimed directly in our
region. Guidance is leaning towards this system being the
strongest in terms of precipitation and moisture for the area,
with temperatures exceeding 50 degrees. On top of that, snow
levels rise even more to around 7000 to 8000 feet. By this time
rivers will likely be running at elevated levels, this will be a
very heightened timeframe for multiple rivers reaching flood
stage, and several other elevated hydrologic impacts. More info
will likely be ironed out in the coming days as we get more river
and QPF guidance.
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