From University of Washington Professor CLIFF MASS BLOG
The latest European Center model forecast for 11 a.m. Friday shows a large low center due west of Astoria with a central pressure of 973 hPa (or mb). “This is extraordinary low pressure for April and a rare event,” University of Washington Prof. Cliff Mass said Thursday morning. Gusts are shown in color and reach 60-70 knots along the Oregon/southern WA coast. This could cause power outages along the coast.
Weather experts are warning a coastal windstorm Friday will be the kind of low-pressure event that “would only be expected once in several million hours,” according to University of Washington meteorologist Cliff Mass. (One million hours equals about 114 years.)
As of 2:52 a.m. Thursday, there was only a high-wind watch from the National Weather Service in Portland for the coastal towns of Pacific, Clatsop and Tillamook counties, with gusts possible to 60 to 70 mph for beaches and headlands from Friday morning through Friday afternoon.
More sophisticated weather modeling from European Centre for Medium-Range Weather Forecasts suggests gusts to 70 knots or 80 mph for the Oregon/south Washington coast.
“The latest European Center model forecast for 11 AM, shows a large low center due east of Astoria with a central pressure of 973 hPa (or mb). This is extraordinary low pressure for April and a rare event,” Mass said. Based on a kind of statistical analysis of weather events, Mass said the low-pressure system generating the wind is “about 5.9 (or 5.9 sigma). This is very large, signifying that such low pressure at the point would be expected only once in several million hours (assuming hourly data was used and the distribution was near normal).”
Compared to the much smaller Oct. 15, 2016 storm that was generally regarded as a false alarm, Mass said scientific confidence in this event is much greater, “with nearly all forecasts having a major storm off our coast.”
Mass said he expects power outages along the coast, however “Fortunately, with a cold winter, the leafing out of the trees has been delayed, which will lessen the damage. And end of winter storms generally do less damage (because a lot of wind pruning has already occurred).”
The wind and low pressure will generate waves of 26 to 30 feet along the Oregon and south Washington coast, Mass said.
Although 80 mph gusts would be a big deal in many places, early winter storms have been known to bring winds of 140 mph to our local area — so this storm may be most notable in the sense that such strong gusts are uncommon at this point in the spring.