Interesting Patterns Ahead

As our tag line implies, interesting wx patterns are modeled to unfold in the near future.  Possibly.  Are you interested?  Grab your Fri morn’n beverage and read on - - -

Today, the middle of November already, will present as partly sunny, with a chance for a shower or two, mainly along the Cascades.  Chilly tonight, with chance for frost in the usual cold spots.  Saturday will start out dry, but another wet ‘warm front’ arrives, followed Sunday by a ‘cold front' - with plenty of cold air support -  presenting wet, wind and mountain snow that could exceed 12” by Monday afternoon.  Snow levels could drop to 1,000 - 1,500 ft in NW WA / 2,000 - 2,500 ft in OR.  Pass travelers should gear up for winter travel over “them thar hills”. 

Backstory.  Recall that key ’storm action’ happens when warm and cold air masses clash.  The boundary between the two, which we humorously speak of as ‘middle of the aisle’ being similar to the clash between political parties, is typically where surface storms form and travel along that boundary.  Well, a Low pressure system currently over northern Japan & the Kurill Islands will rapidly cross the Pacific and 'pair up' with a weak Low to the NW of Hawaii to form a POWERFUL deepening Pacific storm as it approaches the PNW.  Cold air over the Gulf of Alaska clashing with subtropical air over the central Pacific.  Remember our last forecast of the Giant High pressure Wall that models suggested would set up from the Yukon south to NV around Nov 20th?  That still develops on the long-range charts, but gets split in the ‘middle’ along its western edge (over WA, OR, northern CA) by the powerful Pacific storm approaching the PNW.   Oh, by the way, models drop the center pressure to 945-950 mb - equivalent to a Cat 3 hurricane center pressure - when the Low is a couple hundred miles west of Vancouver Island Tue night. But, will we get hit?  Sip.

Back to the forecast.  With the info above in mind, we are changing the forecast for next week.  Instead of dry, with a strong east wind, for much of the week, our weather is now charting as wet nearly every day, turning STORMY on Wed Nov 20 as that Pacific storm moves close to the PNW.   —> Fortunately, the Low will NOT make landfall, rather, it will spin around offshore as it ‘fills’ and the pressure weakens, then it will shift backwards farther west, making room for another Low that will move up from the SW.  This one is likely to generate a strong WIND FIELD for coastal WA & Vancouver Is on Fri Nov 22.  Yes, both storms will spin off moderate-to-heavy rain bands, so expect a wet week, in. general.  There will be a brisk east wind in the Columbia Gorge as the Wed storm approaches, less so for the Fraser Gap, although still windy.  South winds will be the main play in west side locations.  

The weekend of Nov 23,24 is trending with rain moving north from CA/OR border on Sat (mostly dry, mild in WA), turning WET & windy for all on Sunday - and Monday the 24th.  Return to chilly conditions, too.

Thanksgiving Week:  another interesting turn in the weather is possible.  Take another sip.  Model solutions keep a Yukon Dome of 1040+ mb forming and reforming throughout the period discussed above.  By Thanksgiving week, a Yukon Dome is modeled to drop southeast, per usual, and this time it may have an impact on the PNW in terms of the coldest wx thus far in the fall of 2024.  Winds out of the Fraser Gap could be strong by midweek; stronger still on Thanksgiving.  Chilly, but too early for forecast temp - think at least frosty mornings.   High pressure ridge of 1050+ mb possible over northern ID on Black Friday, setting up a windy but dry Thanksgiving weekend.  We’ll see.  These patterns often present snow and or freezing rain issues for west side locations.  More next forecast.