July 15, 2024

A Bone-Dry July… So Far

By Kyra Schlezinger and Joseph Renalds

Hey there Huskies!

Our trademark gray skies have returned this morning in the form of a marine layer push. Their comeback is brief, as this layer will burn off in the afternoon for mostly clear skies and a high on either side of 80 degrees. If we break 80 at SeaTac today, we will be on track for the longest stretch of above 80 degree weather in history. Today would be day 11, and we would need to reach 16 days to break the record. As our run for this record suggests, it has been an unusually warm and dry July here in western Washington. 

We are halfway through July, but there hasn’t been a single drop of rain recorded so far. A bone-dry July is uncommon, but not unprecedented, as July 2021, 2017, and 2013 had only trace rainfall (less than 0.01 inches) amounts recorded. The average rainfall for July is 0.68 inches. 

Looking ahead to Wednesday, a shortwave trough will bring chances for some stormy weather. Chances for storms are highest on the eastern slopes of the Cascades, with mostly dry lightning expected. CAPE values, which are a measure of how much energy storms could have if they develop, could potentially surpass 2000 J/kg in some areas. These values are relatively high by western Washington standards, where CAPE values rarely exceed a couple hundred J/kg in the lowlands. This will primarily be a dry lightning event, so any lightning has considerable potential to start wildfires.

The warm and dry conditions have already allowed the start and growth of wildfires in Washington. The largest fire right now is the Pioneer Fire in north Chelan County. It has so far burned over 15,000 acres and has produced significant amounts of smoke and a pyrocumulus cloud that was visible Sunday evening on satellite.

This smoke has spread over the eastern half of the state and has degraded air quality between Lake Chelan and Grand Coulee. More smoke has remained elevated but if you are headed east of the mountains be prepared for potential degraded air quality.

For now, surface smoke does not look to be imminent because of westerly surface winds bringing in clean air off the Pacific Ocean. However, we could have hazy skies from elevated wildfire smoke as the wind direction aloft brings smoke over us from central/eastern Oregon. Again, this should not impact our surface air quality, but the skies may not be the piercing blue they have been for the last week and a half.

Have a great rest of your week Huskies!