A very large sunspot issued five Earth-directed coronal mass ejections on Thursday, leading the NOAA Space Weather Prediction Center to issue a watch for G4 geomagnetic storm conditions Friday afternoon to Sunday. This is the highest alert category issued by NOAA since 2005.
A G4 storm on NOAA’s scale corresponds to a Kp index value of 8. Under these conditions, the northern lights or aurora borealis could be seen on the northern horizon as far south as Northern California and Alabama. Aurorae may be seen near to directly overhead the Pacific Northwest and Great Lakes with much of Canada (especially Western Canada) likely to experience significant displays.
Having five coronal mass ejections back to back is a remarkably rare event. Readers may remember a double-ejection event in March 2024. Coronal mass ejections are eruptions of material from the Sun, typically originating from sunspots. The sunspot area that generated these ejections is also remarkable – it is estimated to span an area 16 times the diameter of the Earth.
This size puts it on par with estimates of the sunspot area that generated the Carrington Event. While aurorae are typically confined to polar regions, this one in 1859 was strong enough to generate them well into the tropics. Reports of northern lights came in from places like Cuba, Hawaii, and Colombia.
The impeding solar storm is not the same strength as the Carrington Event despite having been spawned by a sunspot area of similar size. The Sun will rotate the current sunspot area to face away from Earth in the coming days.
Coronal mass ejections also create radio blackouts and problems with electrical grids. A G5 storm in 2003 caused power outages in Sweden and damage to electrical infrastructure in South Africa. A large storm in 1989 knocked out power to nearly all of Quebec.
https://ingallswx.files.wordpress.com/2024/05/img_2612-1.png?w=984HRDPS modeled cloud cover for 00:00 PDT Saturday. (WeatherBell)The weather in the Northwestern United States and Western Canada looks ideal for aurora viewing on Friday night. A few scattered high clouds are possible, along with spots of low-level stratus in some coastal areas, but mostly clear skies are forecast. This is thanks to a ridge of high pressure in place over the region.
If you’re in Canada or the northern half of the United States, you can improve your chances of seeing the northern lights Friday night by finding a dark location outside of a city or town with a clear view to the north. Aurora displays are also possible Saturday night.
Note that there is a level of uncertainty with these kinds of forecasts, just like those predicting “normal” weather conditions. Observed Kp numbers aren’t likely to exactly match the NOAA forecast but they should be close. Some uncertainty is also inherent in the timing of the solar storm.
Sunspot frequency varies based on the 11-year long sunspot cycle. Sunspots are the origin of events like this, thus having more sunspots present increases the chances of a geomagnetic storm producing aurora above Earth’s mid-latitudes.
The Sun is currently near the peak of its current cycle. The Space Weather Prediction Center notes that over the course of April 2024 there was an average of 137 sunspots present on the Sun compared to less than 1 for several months during the last minimum in 2019-2020 and 146 in February 2014.
February 2014 represents the peak of the last sunspot cycle. The ongoing maximum is forecast to continue to early 2026 before declining toward the next minimum. While sunspots, geomagnetic storms, and mid-latitude aurora are more common during the peak of the sunspot cycle, occasional storms do strike the Earth around the minimum.
The featured image is of an aurora display in Estonia in 2022. (MaximBilovitskiy/Wikimedia)
I’m so tired of the cold mornings we’re getting in #OlyWA right now. But my partner was kind enough to remind me we actually got snow a year ago, so… #pnw#wawx#pnwwx#OlympiaWA
Shafts of sunlight break through the cloudy sky, illuminating parts of a cityscape of Seattle, WA, that includes our prominent landmark, the Space Needle.
A dissipating cold front is forecast to reach the Pacific Northwest Thursday night to generate mostly cloudy skies throughout the region both Thursday and Friday. Some light rain is forecast west of the Cascades, mainly on Thursday night but a few showers may last into Friday. Friday rain chances are better the further south one goes in Western Oregon.
Southwesterly flow ahead of this frontal boundary may generate a few thunderstorms generally east of a line from Klamath Falls to Pendleton. Some of these storms may be severe, especially in mountainous regions where terrain will enhance upward motion. A marginal risk (level 1/5) of severe thunderstorms is noted for places like La Grande and Ontario.
Saturday
An upper level low is forecast to drop south toward California for the weekend. Mostly sunny skies will be widespread in most of the Pacific Northwest on Saturday, the exception being in the southwestern quarter of Oregon which will be close enough to the low’s center for some cloud cover.
South to southeasterly flow aloft will generate warm temperatures on Saturday. The Portland metro area is likely to reach into the mid-70s (23°C) with cooler weather along the I-5 corridor on either side of the city. Both Seattle and Eugene can expect to reach into the mid-60s (19°C). The Columbia Basin will be in the mid-70s to near 80°F (23-27°C).
Sunday
The upper level low is going to be reabsorbed into the main upper level flow pattern on Sunday and be swept eastward. This will switch mid-altitude winds to become westerly, allowing for some cooling and increased cloud cover. The change in weather will be most notable west of the Cascades.
Some drizzle is possible along the coast and temperatures along the I-5 corridor north of Eugene will be in the upper-50s to low-60s (13-16°C), including both Portland and Seattle. The Columbia Basin will remain sunny but likely shed 3-6°F (1-3°C) off daytime highs.
Next week
Models favor upper level troughing becoming dominant over the Northwestern United States next week. This will bring cooler temperatures into the region. Increased cloud cover with periodic showers are possible throughout the week west of the Cascades but the temperature drop will be most noticeable.
Enough cool air will enter into the region that even under mostly sunny skies the Columbia Basin will generally be below 65°F (18°C) during the first half of the week. Monday looks like the coolest day of the week in Western Washington and Western Oregon; Portland may only see mid-50s (13°C) with rain and a strong breeze.
A widespread hard freeze in low elevation agricultural regions is not expected. That said, a few more sheltered locations in Eastern Washington could tap 32°F (0°C) under clear skies. Models trend toward average beyond day 10 with no strong signal for anything significant.
The featured image is ECMWF modeled temperatures for 15:00 PDT Saturday. (Windy)
#ThrowbackThursday to last October to the Solar Eclipse and a reminder, that we’re going to have about 23% eclipse in our #Seattle#Washington area on April 08th. Use eclipse glasses and a certified solar filter if photographing it.
Wow! Just captured these wave-like clouds from Bellevue, WA.
These are most likely Asperitas cloud formations. Correct me … , hashtag suggestions are also welcome.