Round and Round

Posted by Rufus La Lone on

Friday March 3
Good morn’n, Patron ☕️.  We look ahead to warmer weather, sometime in 2027.  Seriously, here’s the latest long-range outlook.  Hint:  WET.
Staying cold.  The cold pattern will last at least another week.  Freezing level will remain low enough to spur rain/snow mix or plain snow at the surface just about everywhere west of the Cascades through next Wed.  The ‘best times & locations’ to have valley snow, will be overnight tonight into early Sat, similarly for Sunday morning, and again Tue night.  A relatively weak Fraser Gap outflow is possible, esp early next week; Columbia Gorge will have east winds when the surface Low roams west of Astoria.  
Speaking of that Low - a very interesting pattern is charting for 5 consecutive days.  A weak Pacific Low will drop in from the coast of BC this weekend (kicking off the snow tease), and then literally wander in a circle just off the west coast of OR / WA through Wed Mar 8.  Round & Round.  The result will be on/off cold showers, some with rain/snow mixed at the surface, and snow above 500-1,000 ft .  CHILLY days, for sure.  By Thu, the 9th, another, stronger Low will drop in from the NW, and set up an extended classic battle of cold/warm air masses over the west coast by Friday.
Going warmer.  On Friday next, the early stages of the atmospheric battle begins, as colder air from the north collides with warmer, sub-tropical air from the SW in a regional zone somewhere between central/southern OR and the Bay area of CA.  While WA & southern BC may not be completely dry, the bulk of the rain - sometimes heavy - will fall roughly from south of Salem into California.  Rainfall over the weekend of Mar 11,12 (time change) will be fairly minor, but as the week of the Ides of March unfolds, so too will the buckets of rain begin.  Models vary as to where the heaviest rain will fall (the fairly current term for this is ‘atmospheric river’) is primarily CA; Oregon will be slammed with rain, though, esp south of Salem.  As long term Patrons recall, these patterns often trigger strong wind fields; such will be the case.  We’ll narrow down where the wind will be strong as the event time nears (if models verify).  
Tucked into that extended stormy period, is a powerful storm on the Ides of March (Wed the 15th).  The system is currently charting to strike the San Francisco area with dangerous winds and flood-generating rainfall.  It will be a warm storm, as compared to the previous systems, so all the of unusually low elevation snowpacks will melt, contributing to flood issues.  Patrons beware- this system could easily track farther north.  Stay tuned.
Anyway, by late Thu Mar 16, a wet system will move north, aiming right at the PNW.  Rain will increase over all of OR and bring WA into the drip zone.  WINDY.  Note that CA will remain in a very wet pattern, so flooding concerns will only elevate heading into the weekend of Mar 18,19.
Current cumulative precipitation expected between now & St Patty’s Day ranges from 4-5 inches in the Oregon lowlands, to over 6” in southern OR coast range (12"-14” northern CA coast range); snow by the mega-feet in the Sierra Nevada Range.  As noted, WA will be wet, too, just not as much.
Broadly speaking, by the middle of March, the overall pattern should shift back to a seasonal norm, with rain and milder temperatures; low elevation snow around the PNW should end.  Spring flowers should begin to bud, along with Spring smiles and growers looking to work their land soon.
“What America really needs most are those things which money can’t buy."
Copyright © 1994-2023 - All Rights Reserved - The Weather Café ®

← Older Post Newer Post →