There is still quite a bit of uncertainty surrounding the low-pressure system that is expected to approach the Oregon and Northern California Coast on Tuesday. What isn’t uncertain, though, is how strong this thing is going to be.
The National Weather Service (NWS) has Hurricane Force Wind Warnings for a wide area of the Pacific Ocean off Oregon and California. Sustained winds in some places offshore are expected to reach 80 mph with higher gusts. If this happens, it will be the equivalent of a Category 1 Hurricane, which is classified as having sustained winds of 74-95 mph. Remember that hurricanes are classified based on sustained winds, not wind gusts.
WIND FORECAST
This extratropical storm is not expected to have hurricane-force sustained winds when it makes landfall Tuesday, but that doesn’t mean it’ll be weak. Here’s what the NWS Medford had to say in the High Wind Warning they issued for parts of the coast:
This surface low pressure, potentially one of the deepest recorded in recent history, will produce very strong winds across the region.
Coastal regions could see wind gusts up to 80 mph with this system, with exposed areas possibly getting above 100 mph. Despite being so far away from the low-pressure system, the Tri-Cities won’t be spared from some breezy conditions. It won’t be nearly as strong as on the coast, but we could see some gusts to 40 mph. Off toward Yakima, Ellensburg, and Spokane, wind gusts could be even higher.
SNOW FORECAST
Forecasting snow with this system is where the uncertainty still lies. There are two scenarios that we are looking at – a landfall near Crescent City, California and a landfall near Yachats, Oregon. In both of these, there will be copious amounts of snow in the Oregon Cascades as well as Central Oregon.
The Crescent City landfall is definitely the more likely of the two options. This will make it so the low-pressure center is too far south for us in the Tri-Cities to get much precipitation out of it, but will keep us firmly in the cold sector of the system. With this, it seems that whatever precipitation we do get will be pretty limited.
Snow lovers will be hoping for a Yachats landfall. This puts the low far enough north that we will get precipitation but is still south enough to keep us in the cold sector of the storm. The downside here is that even in this situation we only end up with a couple of inches of snow at most.
Even though we will be in the cold sector of this storm, we’re only going to be right around freezing in the Tri-Cities. Under the Crescent City scenario, temperatures would reach cold enough for snow late-Tuesday and rebound warmer after sunrise Wednesday. Temperatures would likely be a little bit warmer if the landfall occurs near Yachats.
In any event, this will be a snowmaker for the Cascades and other mountains around the West. If you are traveling for Thanksgiving, you need to not only prepare your vehicle but make sure you pack to be stuck for a while. When I was on 98.3 The Key this morning, Stacy Lee told a story about how her and her husband got stuck outside Zillah for several hours because of a car accident. Make sure you have things like snacks, water, and blankets because it doesn’t take much snow to cause an accident that could leave you stuck in traffic for hours. Winter preparedness tips from WSDOT can be found here.
WHY ISN’T IT A HURRICANE?
Hurricanes are tropical cyclones that form in regions monitored by the United States Government. Primary responsibility for this is delegated to two hurricane centers, one in Miami and the other in Honolulu. West of the International Date Line and adjacent to our nation’s assigned area, responsibility for monitoring tropical cyclones falls on the Japan Meteorological Agency, who calls them typhoons.
The differences between the extratropical cyclone forecasted to impact the Pacific Northwest and hurricanes are primarily driven by temperature. Extratropical cyclones draw their energy from interactions between cold and warm air masses while hurricanes draw theirs from energy released as warm water vapor rises and condenses into clouds.
Furthermore, hurricanes don’t have any kind of frontal system extending from the core, while extratropical cyclones always have at least one. In the case of the large cyclone forecasted for our region, it is anticipated that it will have two.
