A look at the extreme West Coast weather

AP News
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Posted: Aug 01, 2015 1:47 AM

PORTLAND, Ore. (AP) — Southern California has been pummeled by heavy rain and hail, while the Pacific Northwest is baking in a triple-digit heat wave. Here's a look at the extreme weather:

WHAT HEAT RECORDS WERE BROKEN IN THE PACIFIC NORTHWEST?

Forecasters say the region saw its warmest June on record and July is close to setting a record as well. Thursday's high of 103 in Portland was its hottest day this year, and the hottest day since July 2009.

On Thursday, the high at Sea-Tac Airport was 91 degrees, the 10th day in 2015 with a temperature of 90 or above. That broke the record for the most days hitting 90 degrees or higher for the city. In 1958 there were nine 90-degree days.

IS THIS UNUSUAL WEATHER AND WHAT ARE THE CAUSES?

Forecasters say such heat is not unprecedented. The high temperatures are caused by a strong high pressure system moving over the region that blocks the influence of cool ocean airflows.

WHAT ARE THE EFFECTS OF THE SEVERE WEATHER CONDITIONS?

The hot dry air is sucking more moisture out of plants and warming up rivers and streams. Pasture lands are drying up, and some crops like berries aren't weathering the heat well.

Fish are also dying off, due to extremely high temperatures in rivers and streams.

ANY RELIEF IN SIGHT?

Temperatures are expected to cool down over the weekend and into next week and return to seasonal averages in the 80s. Long-term, the trend of above-average temperatures is expected to continue.

WHAT'S HAPPENING IN CALIFORNIA?

In Southern California, monsoonal thunderstorms have triggered flash flooding, toppled trees and caused power outages. By July 19, more rain had fallen in downtown Los Angeles this month than in all the months of July since 1987.

The rain was welcomed by many as the state weathers its fourth straight year of drought.

WHAT'S CAUSING THE THUNDERSTORMS?

Rain from the remnants of Hurricane Dolores earlier in July set daily and monthly rainfall records in Los Angeles. Thursday's thunderstorms and flooding stemmed from monsoonal patterns that typically peak in August.

WILL THE RAINS GO AWAY?

The atmosphere is beginning to dry out. Flash-flood watches were less widely posted and mainly confined to the Mojave Desert and extending northward along the eastern flank of the Sierra Nevada.

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This story contains information provided by the National Weather Service