Howdy everybody! I’m back after a bit of a hiatus – with our boring weather of late and the first image ever taken of a black hole coming to light last month, I’ve been more focused on the cosmos than the clouds as of late. But with record-breaking temperatures on tap today through Saturday, I thought a blog post was warranted.
Our scorching temperatures are courtesy of a huge ridge of high pressure in the NE Pacific and a resulting thermally-induced-trough trough just off the coast. This thermal trough is associated with gusty easterly winds, and many coastal areas have shattered records today as these easterlies flow down the Coast Range and further warm via a process known as adiabatic warming. To put it simply, when a parcel of air decreases in elevation, it compresses due to a corresponding increase in pressure, and although the total heat content of the parcel remains constant, the temperature increases to account for this decrease in volume.
Credit: University of Washington
Above is this morning’s WRF run from the University of Washington showing the thermal trough along our coast at 5pm today. This graphic shows the temperatures at 925 millibars, or approximately 2,500 feet (apologies for the Celsius… meteorologists are difficult like that). However, temperatures at the surface are much warmer, with widespread 80s throughout Western Oregon. As previously mentioned, the Coast is ground-zero for this heat wave – Astoria’s high of 85 broke their record of 78 set back in 1940, and Newport’s high of 84 absolutely pulverized their former record of 71 set in 1987.
Credit: National Weather Service
With hot temperatures, low dewpoints, and gusty winds, fire danger is extremely high and Red Flag Warnings are up. In their forecaster discussion this morning, the Portland NWS mentioned that 100-hour fuel moisture values as of May 7 were more typical of mid-to-late July and near record values for this time of the year, and those fuels have only dried since then. “100 hour” refers to the typical time lag for fuel to respond to atmospheric conditions; the larger the fuel, the larger the lag. The only active wildfire right now in Washington or Oregon is the Medco B fire in Southern Oregon, but I imagine we’ll see some additional fire reports over the next several days.
Forecast:
The thermal trough currently just offshore will slowly move inland over the next several days and should cross the Cascade Crest Saturday afternoon. As a result, the record heat currently over the Coast will make its way into the Willamette Valley tomorrow, sending highs close to 90 degrees for the Portland metro area on Friday and perhaps the lower 90s on Saturday! The Valley will cool to the upper 70s/low 80s on Sunday, and this cooling trend will continue for the first half of next week, with highs in the upper 60s and steady rain Wednesday as a moderate/strong system takes aim at the Pacific Northwest.
Credit: University of Washington
Models don’t show us warming back up anytime soon. In fact, both the ECMWF and GFS ensembles keep us wetter-than-normal through the following week, with near or even slightly below-normal temperatures! This will help moisten our fuels and assist firefighters with any blazes that might flame up over the next few days.
Cold Rivers and Hypothermia
Finally, it’s worth highlighting the fact that even though temperatures will soar into the upper 80s/low 90s across NW Oregon and SW Washington Friday and Saturday, it’s still early May and rivers are much higher and colder than they are during the summer, particularly those that are fed by snowmelt. I’m planning on heading to the beach sometime this weekend and recommend you do the same if you are up for it, but please remember that even though the atmosphere will be hot, the water will be anything but. I can recall previous instances of people drowning and/or experiencing hypothermia during these April/May scorchers – be smart and play safe!
So to recap: don’t start any wildfires, be cautious when you are at the beach, wear tons of sunscreen, don’t forget to roll down the windows for your dog in your car, and have a ton of fun enjoying the record heat tomorrow/Saturday and the unseasonably warm weather on Sunday. 🙂
Charlie
