Christmas Week Uncertainty

Christmas approaches so let's dive into the forecast for the week ahead!

Today the day has started out very nicely with temps in the mid to low 40's for much of the area. But a system will cross the area today afternoon and evening bringing about rain and mountain snow. After the front crosses, tomorrow should be fairly benign with some showers in the area. Then the forecast becomes extremely complicated as we head into Christmas Eve. 

Christmas Eve:

About 2-3 days it looked like it would just be normal weather (45 and rain) for most of the region. But suddenly models began picking up on the potential for a windstorm, a particularly historic one at that. 

The European model had been showing a low pressure system strengthen near the California coast and track almost due north, casting an intense pressure gradient over Western Oregon and Washington. 


This would be disastrous for the region as a whole, wind gusts of 70 - 80 MPH in the Willamate valley and up to 60 MPH continuing into the Seattle metro on Christmas Eve evening. With the recent flooding, this would an extremely dangerous situation for millions of people who live in this region. Now you may wonder why you haven't been hearing about this yet. There is significant uncertainty in whether this will happen or not. The run here is today's 6z EURO run, let's look at the next run. 



The 12z Euro looks absolutely nothing like the 6z. The low tracks further inland and is significantly weaker, winds barely cross 40 MPH for most of the area. This kind of run to run change only 60 hours out is very unusual. To add to the uncertainty, there is barely any agreement between the models. Each one is portraying a different scenario, resulting in wildly different outcomes. In addition to this, the timing couldn't possibly be worse: Christmas Eve evening. All of these factors make this one of the most difficult forecasts in recent times. I will continue to keep you guys updated but until then everyone needs to keep an eye on the forecast for Christmas Eve.

Comments

Post a Comment

Popular posts from this blog

Widespread Lowland Snow Incoming!!

Image
 Well it is going to be an interesting 48 hours coming up. We will have snow, ice, sleet, rain, wind, basically everything on the weather bingo card in the next 2 days.  A strong and moist Pacific system will move into the area tomorrow evening, spreading precipitation into a very cold and dry air mass. A ripe set up for a snowstorm in the PNW.  Current satellite imagery shows moisture moving into Oregon.  This moisture will spread north and with the cold temperatures in place, it will bring wintry weather to the lowlands of Oregon and Washington. Winter and ice storm warnings are out for Portland and the Willamete valley. This storm will work effectively to scour out cold air in the upper levels so I expect precipitation type to quickly transition to freezing rain and sleet south of Salem. However, upper levels should stay just cold enough for precipitation to remain snow north of Wilsonville.  The low will pull east winds out of the gorge, keeping things very ...
Read more

Friday Night Update

Image
The much talked about potential for lowland snow is finally here and we are in the range where we can talk about specifics. Tonight, a cold front is crossing the area, evident in satellite imagery.  Behind this cold front is much colder air which will filter into the area tonight. Temps are sitting in the upper 40's currently in much of the Puget Sound, by about 2 AM, much of the area will be in the 30's and a gradual cool down will continue. At this time there are several chances for lowland snow, but accumulations will be spotty as the system is more showery in nature and not organized.  There will be several areas with a heightened potential for lowland snow and I will point it out on this little graphic.  Zone 1 is in Snohomish county and has a heightened potential for snow due to the convergence zone setting up over there tonight and into tomorrow. There is a chance this extends southwards briefly so some of northern King county could also see some snow. I expect abo...
Read more

Evening Update

Image
 We are very close to tonight's snow potential and models still have no idea what will happen. Looking at Sattelite imagery, the low pressure we have been tracking looks to be a bit north of Hoquiam. How north this low goes will determine which area gets the most moisture. Earlier this area looked to be King County and the Central Sound, but now this area may have shifted a bit northwest. Northern King County and the Kitsap peninsula.  As I said earlier, this looks to be a bit more widespread in terms of moisture, but temps look to be more marginal so elevation will definitely aid with snow. Looking at the graphic below, the area circled in blue will have the most access to moisture tonight. In this area, places above 500 feet should see 2-8 inches of snow. Below that, 1-3 inches of snow seems likely. Another wildcard going into tonight is the deformation band as the low passes to the south of us, the models are struggling to nail that feature but if it does form then areas un...
Read more