It’s not much, and not everybody will get wet. But for the first time nearly two months, rain is in the forecast for parts of the Pacific Northwest!
Created with PSD Interactive Climate Analysis and Plotting Web-Tools with NCEP/NCAR Reanalysis Data
The summer of 2017 has been extraordinarily dry for the Pacific Northwest. Following a soaker on June 15 that dropped 0.42 inches at Portland and 1.05 inches at Sea-Tac airport, both places saw a few drips on the 16th and 17th (respectively) and have been bone-dry since. On Monday, Sea-Tac airport recorded their 52nd consecutive day of no measurable precipitation, breaking the record of 51 days set in 1951. But thanks to a pattern shift of titanic proportions, Portland will have trouble breaking their amazing 71-day dry streak set in the summer of 1967.
Today will be another hot and hazy day as a strong ridge centers itself directly over the Pacific Northwest.
But by Friday, this ridge has weakened significantly and moved to the east, giving us weak southwesterly flow aloft. This will help cool temperatures ever so slightly and should help disperse some of the wildfire smoke currently over the area.
If you look closely at the graphic above, you can see a weak shortwave trough off our coast around 130 degrees west (look for the dip, or “trough,” in the height contours and the band of enhanced vorticity). This shortwave will make landfall late Friday night and could bring a few drops of rain to the Portland metro area in the process. However, last night’s UW WRF model shows the vast majority of rainfall staying east of the Cascade crest.
Credit: UW Atmospheric Sciences
A better chance of rain comes around Sunday evening as a stronger cold front moves through the area. However, there is considerable uncertainty with how much rain this feature will bring, or even if it will bring any rain at all. While the European model shows Portland’s dry streak ending on Sunday, the GFS gives very little precipitation, and the GFS ensembles (below) are all over the place.
Credit: Environmental Modeling Center
Portland needs to remain dry until Sunday, August 27th to break their record, so even if we escape unscathed from this Sunday’s system, we’ll still need two more weeks of dry weather to break the record. With models advertising slightly below-normal temperatures and near-normal precipitation for the rest of August, our chances of breaking the record are on par with the chances of booking a hotel in Madras for the Monday, August 21 solar eclipse. Not too good!
Speaking of the solar eclipse – it’s too early to put out a precise forecast, but preliminary indications are that we won’t have a massive ridge over the area, increasing the probability of a morning “marine layer” west the Cascades that could hamper viewing of the 10 A.M. eclipse. Look for a “solar eclipse” blog in the next couple days, and I’ll keep you posted with forecasts as the eclipse draws nearer.
Have a great Wednesday!
Charlie
2 Comments
Seattle Times today also says rain is unlikely “Little chance dry days to end soon,” although a possibility on Sunday. Was interested to see that the record low was 47 in 1974. I was working as a camp counselor in the Cascades that summer, and I remember pulling out some long underwear. Hard to imagine today!
Hidden Valley Camp cools off dramatically at night – much more so than Seattle. Mornings can be downright cold – even in the hot summer of 2014, it was very cold coming to work in the kitchen in the morning!