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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