Record-breaking hot weather smothers outer East Portland

INCLUDES ILLUSTRATED WEATHER VIDEO | A National Weather Service meteorologist, at our Parkrose neighborhood weather station, explains the latest heat wave – and tells what we might expect over the next three months …

During the early July heat wave, the Creston Pool was a good place for people to cool off during the sweltering days.

Story and photos by David F. Ashton

After five sequential record-breaking high temperatures in outer East Portland – from July 5 through July 9 – It’s finally “cooling off”…. if one considers 90° afternoons “cool”.

As the thermometer was climbing to a high of 104° on July 9, apparently it was just too hot for families to enjoy Portland Parks & Recreation’s interactive fountain “Splash Pads” at Gateway Discover Park, Raymond Park, and Earl Boyles Park – there were few of them there.

Although the “Misting Stations” at many parks are hissing water vapor, often, no one was enjoying them in the 100°+ temperature afternoons.

At his workstation, inside the National Weather Service Parkrose office, we found Meteorologist David Bishop, ready to explain the unusually hot weather.

To discover the science behind the heat wave, East Portland News visited National Weather Service Meteorologist David Bishop at the Parkrose neighborhood regional weather station, on July 9 – the hottest day of the year so far.

High pressure area stalled
“What’s been causing this period of extreme heat for us is what’s called an ‘Omega block’ in the upper levels of the atmosphere, over the Portland area,” Bishop began. “It’s called an Omega block because the weather system looks like Greek symbol for Omega [Ω] – much like a horseshoe shape.

Meteorologist David Bishop points to the low pressure system, stalled to the west of the high pressure, stalled over Portland – causing the excessive heat.

“This is flanked by two relatively low pressure systems. It’s strong enough to block or prevent a pattern change coming into the area,” continued Bishop. “In this case, there are two low-pressure systems – and rather than being able to push the high-pressure out of our way, they take the path of least resistance and opt to go around the high-pressure system.”

Watch, as National Weather Service Meteorologist David Bishop explains this record-breaking weather system:

Atmospheric compression produces heat
This stalled high-pressure system is in the upper level of the atmosphere, rising some 18,000 feet in elevation, resulting in relatively lower pressure at the surface.

“This causes ‘compressional heating’ – that is, the upper air in the atmosphere gets pressed down harder and harder, into a smaller and smaller contained area – which causes air molecules start moving faster and faster, and to start warming up.”

The reason for the subsequent relative cool-down starting July 10th is a low pressure system in Canada moving eastward, “flattening out” our stalled high-pressure system, deforming it, and getting it moving to the east.

For three afternoons, the iconic Division Station temperature gauge in the Powellhurst-Gilbert neighborhood shows readings of 100° and higher.

Record Temperatures
Although the 4th of July Holiday was warm, it didn’t break any records, including the previous record set in 1972. But on the five days after that we had daily record-breaking high temperatures:

Heat shimmers off the National Weather Service building in the Parkrose neighborhood, as meteorologists inside puzzle about what to forecast for the remainder of the summer.

Uncertain future forecast
Our weather for the rest of the summer? “It’s a little challenging to say at this moment,” Bishop replied to our query.  “Looking to our Seasonal Temperature Outlook map for July, August, and September – it shows there are equal chances for temperatures being above normal, normal, or below normal.

Meteorologist David Bishop points out the “equal chances” notation for Oregon on their Seasonal Temperature Outlook map.

“So, here’s what this means: For the next three months – Oregon, and a good portion of the Pacific Northwest, has no real clear signals about how temperatures and precipitation are going to shake themselves out.”

But for sure, there is a clear recent trend toward warmer and warmer temperatures than normal in all seasons, and there seems no reason to believe the trend won’t continue. Make sure any future hot summer weather does not threaten your health and safety!

© 2024 David F. Ashton ~ East Portland News™