STORMY then COLDER

Where do we start?  Wow, lots of impactful weather about to hit the PNW and California.  Extra-size your morning beverage, this will take some time to absorb.  It is important.  Ready?

Probably best to break this monster forecast into 2 Parts, as each piece could have ramifications on life & property, depending on your location.  (Remember Patron, our forecast discussions cover BC, WA, OR, CA and ID, so while your specific area may not have a serious impact, another area in our region very well could.)  Enough said.

—> Biggest adjustment since our Saturday Special Statement is that the heaviest rainfall, and thus risk for MAJOR flooding, has been shifted, by the models, farther south into Northern CA, generally north of the Bay area up into the southern margin of OR.  That’s NOT to say the rest of the region will escape lots of rain and localized flooding of small creeks and urban area (leaf blockage of storm drains).  

Kuril Islands Storm - This system is continuing to develop, with the potential for center Low pressure to rapidly fall (hence the term ‘bomb cyclone' used by some) to 941-950 mb by the time it is a few hundred miles west of Vancouver Island.  That is equivalent to a major hurricane.  WINDS will be strong from the EAST, as the storm approaches, but it will NOT make landfall (thank goodness the High pressure Dome will block further eastward movement).  Interestingly, the actual Low will rotate offshore and spin farther West before returning as a weak Low to northern CA a week from now.  

WINDS.  Strong winds along the west coast from Bay area north to BC; inland S winds could gust to 40 mph.  It could be the powerful EAST winds, pushing out from that formerly Yukon Dome as it settles to our east, that could have impact.  The Gaps - Fraser & Columbia Gorge - will be very windy.  Even Cascade passes will be very windy.  Also, as the S wind clashes with the E wind along the western edge of the Cascades, winds will be intense.  Falling trees possible given saturated soils.  Power outages, too.

RAIN.  As noted above, inches of precip is likely for all locations west of the mountains between late Tue and Saturday.  Northern CA could have MAJOR ISSUES with flooding, as models indicated 7”-9” in the period.  To quote Behringer, Nat’l Wx Service, San Francsico, “getting caught up on whether a storm is a ‘bomb cyclone’ or not does not effectively communicate the associated impacts on life and property”.  OR & WA may have dodged the high risk of major flooding this time.  Generally, rain should let up a bit on Fri, except for northern CA.  The weekend is trending damp on Saturday, turning cooler & drier on Sunday.  

COASTAL EROSION.  Beach communities will experience lots of high wave action and beach erosion.  Patrons in these locations must remain alert.

Thanksgiving Week is trending drier but NOTABLY COLDER.  Yukon Domes will continue to have influence on PNW wx conditions, as a ’second’ Dome moves SE out of Canada.  The air will dry beginning Sunday, and an East wind will pick up.  Indications are that by Tue, wind will rush down the Fraser Gap (not severe!), cooling the Puget Sound region.  Not so much out of the Columbia yet.  A weak system from the west could bring rain onshore overnight Tue.  Will it be cold enough for rain/snow mixed at the surface?  We’ll see.  Anyway, on Wednesday, showers will begin to diminish late day, and the Fraser Gap winds will return - this time building into a major wind event for the northern portion of the Puget Sound.  Rain continues over western OR overnight Wed into Thanksgiving Day.

Thanksgiving.  Moderate rain all day in OR, heavy rain all day in CA, and turning COLDER in the Puget Sound area, with the Fraser Gap wind howling.  In fact, Patrons around Lynden, etc should prep for potentially damaging winds & possible power outages overnight Thanksgiving into Black Friday.  We’ll update this, of course.

Strong east winds out of the Columbia Gorge Sunday Dec 1st.  Another very WET week will follow Thanksgiving Weekend.  This time we may NOT dodge the flood-bullet.  More on that in the next report.  

Bottom line:  the blocking High pressure ridge inland is literally saving the PNW from an extremely dangerous wind event.  Potential barometric pressures - in what we have coined the “Kuril Islands Storm” - are way below that of the Columbus Day storm in 1962.  While the storm will not get too close to our coasts, it will have impact, so please heed all the watches and warnings issued by the Nat’l Wx Service.