Tuesday brings clear skies, warmer temps

Weather Blog

Next chance for sprinkles may arrive Friday

PORTLAND, Ore. (KOIN) — Tuesday and Wednesday will deliver clear mornings and pure sunshine with warmer temps reaching the mid-80s in the valley, possibly upper 80s for the south end of the valley. UV Index will be very high through Thursday.

Our next chance for sprinkles may arrive Friday. The most likely target, however, would be the far NW corner of Oregon and western WA.

Nineties in the forecast? It’s possible by Sunday and Monday. It won’t be the first 90° this year at PDX but it will be the first for this month. June had one day at 93° and May had one day at 91°. Would you believe we’ve had more 60-degree days than 80-degree days this month!

Visuals overnight: It will be nice and clear for the next few nights. We’ll be in a new moon phase soon which will help you identify these beauties. What’s out there for eye candy?

1) Click here to learn more about Comet Neowise.

Comet Neowise soars in the horizon of the early morning sky in this view from the near the grand view lookout at the Colorado National Monument west of Grand Junction, Colo., Thursday, July 9, 2020. The newly discovered comet is streaking past Earth, providing a celestial nighttime show after buzzing the sun and expanding its tail. (Conrad Earnest via AP)

2) Aurora: Here’s the official 30 minute forecast.

What causes the aurora borealis? According to the Space Weather Prediction Center/NOAA:

The Aurora Borealis (Northern Lights) and Aurora Australis (Southern Lights) are the result of electrons colliding with the upper reaches of Earth’s atmosphere. (Protons cause faint and diffuse aurora, usually not easily visible to the human eye.) The electrons are energized through acceleration processes in the downwind tail (night side) of the magnetosphere and at lower altitudes along auroral field lines. The accelerated electrons follow the magnetic field of Earth down to the Polar Regions where they collide with oxygen and nitrogen atoms and molecules in Earth’s upper atmosphere. In these collisions, the electrons transfer their energy to the atmosphere thus exciting the atoms and molecules to higher energy states. When they relax back down to lower energy states, they release their energy in the form of light. This is similar to how a neon light works. The aurora typically forms 80 to 500 km above Earth’s surface.

Earth’s magnetic field guides the electrons such that the aurora forms two ovals approximately centered at the magnetic poles. During major geomagnetic storms these ovals expand away from the poles such that aurora can be seen over most of the United States.


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