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This is the weekly weather briefing for Western Washington for Friday April 19th through Thursday
April 25th. Do not use this briefing after noon Saturday, April 20th.
A transition from rainy weather to sunny, warmer weather will occur next week. The rain
Friday morning will turn to scattered showers over the weekend. A ridge of high pressure
will build next week with a warming trend. This is the set of solutions for the 850mb
level temperatures through the next two weeks, courtesy the German WeatherCentral website
http://www.wetterzentrale.de/ The 850 millibar level in the atmosphere is near 5000 feet.
After a quick dip in the temperatures aloft through Sunday the 21st, nearly all the ensemble
members show a warming trend with no precipitation. It is likely that higher pressure aloft will
build into the region next week. It is likely that high temperatures across the lowlands
of Western Washington will warm into the mid and upper 60s next week, with 70s possible
if the warmer ensemble members are correct. Here is a short sequence of 500 millibar height
forecast charts that show the building high pressure aloft into next week. 500 millibars
is around 18000 feet. This chart is Saturday. Here is Tuesday. Note the heights show around
570 over western Washington.
The upper level ridge is still centered offshoreóit will need to shift east over the area if temperatures
are to get really warm. Here is one forecast of sea level pressure
forecast for the middle of next week. This is the sort of pattern that starts to
give us our normal summer northerly windógood for sailing in the afternoon
and evening hours. The thermal trough is still over California,
but it is starting to edge north into Western Oregon.
After cloudy, showery and cool weather over the weekend,
there is a good chance that high temperatures will warm
well into the 60s, and perhaps the 70s by mid week.
The freezing level in the mountains will rise from around pass
level over the weekend to around 10,000 feet midweek.
Northerly flow will develop as thermally induced low pressure sets up to the south.
This weather pattern promises sunshine and warm weather next week. The sun angle is the
same as in late August. This warm spell might lure some people to area rivers and lakes.
Rivers are running cold and swift and the rivers are icy cold. On Friday, State Parks
and the National Weather Service issued a joint press release urging people to be prepared
if enjoying rivers and lakes across the state during the warm weather. Wear a life jacket!
Here are some resources for further information. In particular, you can visit our National
Weather Service Seattle website, at weather.gov forward slash seattle.
Thanks for viewing this briefing, have a good weekend and enjoy the warm sunny weather next
week.