Get Ready for Major Rain and Wind Events

The National Weather Service (NWS) is forecasting heavy rain and maybe windy conditions Tuesday through Thursday Oct. 17 – 19, and again Saturday Oct. 21.  Be prepared — clean gutters and drains, and have supplies for a possible electricity outage.

Below are excerpts from today’s 8:39 AM forecast discussion.  You can access NWS forecasts for Seattle online.

Today really is a good day to make preparation for the upcoming
stormy pattern…like making sure gutters are clean, drains are
cleared of any early fall leaves, lawn furniture is brought in,
etc. The weather will go down hill on Monday night as the front to
the northwest approaches the area.

Tuesday will be wet and breezy as the front moves southeast
across the area during the day.

Looks like a stormy fall day on tap for Wednesday, probably requiring the
eventual issuance of wind- related and possibly flood-related
watches, warnings, or advisories. A jet streak will develop in the
base of an upper trough over the Gulf of Alaska. As the jet noses
into B.C., it will push a strong warm front inland on Tuesday
night. This will bring a new round of heavy rain, though the ECMWF
hold heavy rain off until Wed morning. Southeast gradients will
become tight on Wednesday, supporting windy conditions. Windiest
weather will be in southeast-wind prone areas, such as the coast
and areas from Everett north through the islands and Bellingham.
Statistical guidance from the GFS and ECMWF show sustained winds
at Whidbey Island reaching 34 knots and 31 knots respectively. The
first such wind event of the autumn is commonly more impactful
than a similar event later in the season, after nature`s tree
trimmer has already been through a few times. As for rain, models
are developing a consensus in keeping heaviest rain over the
windward Olympic Mtns and North Cascades. The 06z GFS shows
24-hour rain totals as high as 8 inches over the northwest Olympic
Mtns as of 11 pm Wed. The official NWS forecast has 6.5″ at this
wettest location during the same 24 hours. Currently looking for
3-4 inches over the North Cascades. The interior lowlands
currently forecast to range from 0.75″ south of Olympia to near 2″
around Bellingham. See the hydrology section for more impacts.

An upper trough will make headway off the eastern Pacific, pushing
a cold front through Western Washington on Thursday. Once it
passes, the atmospheric river type weather should ease. Cool and
showery post-frontal conditions will prevail on Friday.

Yet another strong, consolidated jet will nose into the Pac NW and
B.C. next Saturday. Looks like this will be another atmospheric
river setup for heavy rain. With 850 mb southwest winds of 40-60
kt, should be windy too. Haner

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