The Bellingham Heat Surge and Improving Air Quality

On Thursday afternoon, the temperature at Bellingham, Washington, surged to 100F, breaking the all-time record for any day at that site.

Not surprising the previous all-time record (99F) was set during the extreme heatwave of late June this year, something illustrated by the plot of high and low temperatures at Bellingham this summer (below, purple shows daily high temperatures, cyan, daily low temperatures)

The interesting thing is that locations a few miles south of Bellingham were warm but nowhere near record-breaking levels that day (the high temperatures on Thursday are shown below, click on the image to expand).  Looking closer, there appears to be a swath of 100F temperatures extending from the Fraser River Valley and very warm highs over northern Victoria, BC.

Looking even closer, there were temperatures as high as 106 and 107F to the northeast of Bellingham!  Wow.

What in the world was going on?

I think there is an answer to this strange anomaly.  The effects of strong downslope flow, accentuated by the proximity to the Fraser River Valley.  As air sinks, it warms by compression.

Plotting the winds at 1 PM on Thursday, the northeasterly flow coming out the Fraser River Valley was obvious (red numbers are gust speeds, temperature to the upper left of the circles).

And looking at the surface observations at Bellingham Airport, the big temperature surges accompanied the strongest northeasterly winds.  You will notice that the temperatures surged from 72 to 91F in two hours as calm winds switched to strong northeasterly winds (direction of 40°--northeast, gusts to 26 knots).

It just so happens we received wind reports from aircraft arriving and leaving nearby Vancouver Airport that day (below).  Strong northeasterly winds aloft around 2 PM.

And strong, localized northeasterly surface winds pushing out the Fraser River Valley are found in the high-resolution UW WRF simulation for 2 PM Thursday (below).   Very warm temperatures were predicted to accompany the strong winds (pink colors).

Moving to a higher elevation (around 5000 ft, 850hPa pressure), the existence of high pressure/heights over BC and a trough (low) along the WA coast, led to a strong pressure/height gradient that produced strong northeasterly flow in the lower atmosphere.

Northeasterly flow that warmed as it descended the western slopes of the Cascades/BC Coast Mountains.  A current of such warm air descended into the Fraser River Valley and then jetted into Bellingham.

Importantly, high-resolution models accurately forecast this situation well ahead of time--and humans (admittedly including myself) did not spot it before it happened.  To show this, here is the previous day's high-resolution ensemble forecast for surface air temperature at Bellingham....upper 90sF were being predicted.

Closer in forecasts were even better.  

This event has gotten me thinking.  Our models and forecast guidance is getting so good now that we need a software system that will monitor the forecasts and bring unusual events to the attention of forecasters.  Sort of like the flight management systems on airlines.

Improving Air Quality

Finally, with the low-level influx of marine air last night,  air quality is vastly better in western Washington and temperatures are decidedly cooler.  Here is the latest EPA AirNOW graphic, with green circles showing good air quality.    There is still some smoke aloft, but that should slowly decline over the next day.

Still poor air quality in eastern WA, but it will improve there dramatically on Monday.