John Homenuk

What to know before getting excited about the aurora

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As hype for the potential to see the aurora borealis this weekend increases, thousands of people are now eager to step outside around midnight tonight to glowing, moving multicolored lights in the night sky.

They’ll be disappointed.

There are a few things to know which will not only keep your expectations in check, but also keep you more knowledgeable regarding the phenomenon in the future.

During the middle part of this week, two solar flares occurred from the an Earth-facing sunspot. Solar flares are essentially eruptions from the sun which send energy, light, and high speed particles flying into space. If these flares occur on a part of the sun which is facing earth, eventually the energy, light and particles will reach our planet. These flares are often associated with magnetic storms called CME’s, or Coronal Mass Ejections. Although solar flares aren’t harmful to humans (thanks, atmosphere) they can create long-lasting radiation storms above our heads — and disrupt high frequency radio signals, GPS systems, and satellites. They also can produce beautiful aurora borealis in the night sky, especially in the Northern Latitudes.

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John Homenuk

Multiple CME’s prompt geomagnetic storm watch

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As we mentioned in a post yesterday, the sun has been very active of late. In fact, another solar flare today means that the sun has erupted with two M-Class solar flares and one X-Class solar flares in the last three days alone. The first two solar flares, from the same sunspot, are both earth-directed — and moving at a reasonably fast pace. The Space Weather Prediction Center issued a Moderate (G2) Geomagnetic storm watch for the first M-Class solar flare, and has since issued a G3 (Strong) geomagnetic storm watch for the X-Class solar flare, expected to reach Earth on Saturday.

As NASA puts it, solar falres are giant explosions on the sun that sent energy, light and high speed particles into space. These flares are often associated with magnetic storms known as CME’s, or Coronal Mass Ejections. Both of the two major solar flares from Tuesday and Wednesday were associated with CME’s. Although solar flares aren’t harmful to humans, solar flares and CME’s can create long lasting radiation storms above our heads — which can harm satellites, communication grids, and even power grids on the ground.

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Doug Simonian

Scattered thunderstorms later today in advance of strong cold front

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After a lovely fall day on Wednesday, the humidity is back on the rise, as we revert back to summer. The culprit is a storm system and associated strong cold front — the latter of which will be passing through our area on tonight. Immediately out ahead of it, however, will be an increase in southerly winds and a warmer airmass. Often times, a warm, humid airmass in conjunction with a strong cold front can trigger strong thunderstorms. Initially, the threat for severe weather looked pretty high, but as we illustrated in yesterday’s article, there was major uncertainty as to the degree of instability that the atmosphere would hold. As we approach Autumn, high instability values tend to be harder to come by, and as we got closer to today, models gradually backed off on the degree of instability.

CAPE stands for Convective Available Potential Energy — the higher these values are, the more potential the atmosphere has to support strong, organized lifting for strong thunderstorms. Typically, values around 1,000 J/KG support marginal severe weather, while values 1500 J/KG and higher are more likely to support severe weather. With our area hovering only around 500 J/KG, it will be hard to expect much in the way of severe weather. That being said, this cold front will pack quite the punch with potent dynamics. This will allow for strong wind shear — in the order of around 40 knots — from the surface through the middle of the atmosphere. This means that any thunderstorm that does form could still produce strong wind gusts. Notice how further to the south, the CAPE values are higher, but the wind shear values are much lower — there is no truly impressive juxtaposition between the instability and the wind shear that is often necessary for widespread severe thunderstorms.

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John Homenuk

X Class solar flare could produce bright aurora

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Two CME’s (Coronal Mass Ejections) from the sun during the last two days have astronomers brimming with excitement. And although the details aren’t totally certain, the earth-directed nature and magnitude of the solar flares have photographers racing for their cameras in hopes of capturing the elusive aurora borealis.

At 1:45pm today, an X-Class (strongest level) solar flare occurred — right on the heels of an M Class flare from Tuesday. Sunspot AR2158 is the culprit. A geomagnetic storm watch has been issued as a result of the Tuesday ejection from the sun. That  flare, despite being weaker than Wednesdays, was long duration — lasting almost 6 hours. During the last few weeks, multiple weaker CME’s have produced auroras throughout the world. The incoming aurora could be brighter, last longer, and extend farther south from the poles than its predecessor.

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