This past Sunday, I went trout fishing on the Yakima River with my dad and brother. The trout were there, but they were sluggish and not particularly enthusiastic about our flies. We didn’t had any hits on dry flies and had a few hits on nymphs, but we were unable to bring any to the boat. Despite getting skunked, we still had a wonderful time floating down the river and taking in all the scenery that the Yakima has to offer.
But even though the fishing was slow, the trip was very eventful from a weather perspective. We picked one of the rainiest days I can ever remember experiencing in Central Washington to do our float, and it definitely felt at times like we were floating a river west of the Cascade crest. But with proper rain gear and waders, we were plenty comfortable the duration of the trip.
Current Conditions:
We are currently experiencing strong, westerly flow in the wake of a powerful cold front that brought steady rain to Western WA/OR through mid-morning and moved east of the Cascades around noon. This front was associated with a strong, 990mb low that made landfall near the northern tip of Vancouver Island at approximately 7am this morning.
Credit: College of Dupage
The visible satellite image above shows how dramatic the orographic (terrain-induced) rain/snow and leeside rainshadowing are when flow is due westerly and perpendicular to the north-south oriented Cascades. Air is forced to rise on the windward slopes, creating clouds and precipitation. After this air crosses the Cascade crest, it sinks on the leeward slopes, drying and warming in the process.
Credit: NWS
Today’s system marks the third strong system in five days. Friday night into Saturday morning, a strong cold front brought heavy rain and breezy conditions to Western Washington and Oregon. An EF-1 tornado even touched down at Moclips, WA around 4:45 am on Saturday, right as the storm’s intense cold front was making landfall along the coast. Another strong system brought heavy rain both west and east of the Cascades Sunday afternoon and evening. Today’s system brought another round of heavy rain and was probably the windiest of the bunch, particularly east of the Cascades.
The rainfall totals since Friday are very impressive, with 1-3″ common in the lowlands and as much as 5-10″ in the Cascades and Olympics.
Credit: NWS
As of 6pm, winds have decreased dramatically west of the Cascades and all wind advisories have expired. High Wind Warnings are still in effect for much of Central/Eastern Washington & Oregon through 11pm tonight.
Forecast:
Summary:
- We’ll enter a much calmer pattern beginning Wednesday and persisting through Saturday compared to the active weather we saw from Friday through Tuesday. Precipitation will be below-average and temperatures will be near seasonal normals.
- On Sunday, cool arctic air will push into the Intermountain West. Some of this air will spill into the Columbia Basin, and the Portland metro area may see cool, gusty easterly winds beginning Sunday and persisting through early next week, with temperatures moderating slightly by late next week
- By next weekend (Saturday 10/24), we may transition to a cooler and wetter pattern with a ridge over the northern Pacific and cool, moist northwesterly flow into our area. This pattern is unlikely to give us any strong systems but could allow a steady parade of weak-to-moderate systems to come through the Pacific NW.
Details:
Wednesday will feature decreasing showers as a weak ridge of high pressure begins to build offshore, and Thursday should feature mostly sunny skies as this ridge strengthens. With low winds and wet soils, Thursday morning and Friday morning should feature fog that will burn by midday.
Models have quite low confidence beginning Friday evening (10/16), and this is illustrated clearly below by the large “spread” in the GFS ensembles beginning at 00Z 10/17 (5pm PDT 10/16). Models show a weak ridge of high pressure over California creating warmer and drier-than-average conditions for California and the Desert SW and sending the storm track towards British Columbia while a deep trough allows cold, Canadian air to move south towards the Northern Rockies. The fact that the Pacific Northwest is right between the trough to the east and ridge to the southwest means that small changes in the location of either of those features have large effects on the forecast.
By Sunday morning, this trough will push cool, dry, Canadian air into the Columbia Basin, creating offshore gradients and breezy easterly winds through the Columbia River Gorge and into the Portland metro. This will be a much weaker east wind event than the catastrophic one we experienced on Labor Day and there is no fire threat here. However, these cool east winds will feel quite crisp, so be sure to bundle up!
Credit: University of Washington
The weather may turn wetter by next weekend as the ridge along the West Coast retrogrades offshore and a trough forms downstream across the West, giving northwesterly flow with cooler and slightly wetter-than-average weather. This is a very typical La Nina pattern, and though it isn’t ideal for giving us strong storms with heavy rain and strong wind, it is a great pattern for early-season mountain snowfall.
As currently shown, the ridge is closer to our coast than ideal, meaning that the bulk of cold air and moisture is directed towards the Northern Rockies instead of the Cascades. There is plenty of time for the ridge to retrograde further west and the cold air and moisture to shift accordingly, but any mountain snow would still be relatively light and confined above 3,500 – 4,500 feet. It’s simply too early for us to get any significant mountain snowfall, but it’s encouraging to see this pattern in the models nonetheless.
Thanks for reading and have a great week!
Charlie
