Space Weather Forecast Headline:  Chance of G1/Minor storm, mainly Day 3 (11 Sep).

Analysis of Space Weather Activity over past 24 hours

Solar Activity: Solar activity was at Low levels, with occasional Common-class flares observed. 

There are currently up to eight sunspot regions visible on the solar disc. Most regions remain relatively simple, unipolar groups. The exception is a small bipolar region in the north centre disc. No Earth directed Coronal Mass Ejections (CMEs) have been seen in available imagery in the last 24 hours.

Solar Wind / Geomagnetic Activity: Solar winds reflected the waning coronal hole high speed stream influence. Wind speeds were initially elevated initially, peaking around 570 km/s, but gradually declined to 400km/s. From around 09/0410 UTC speeds increased modestly, peaking around 470km/s. This was likely due to a weak CME arrival. The Interplanetary Magnetic Field was largely weak but became occasionally moderate in strength following the weak CME arrival. The important north-south component varied weakly but was often southward directed. Geomagnetic activity was Unsettled to Active (Kp 3-4) 08/1200-09/0300 UTC, becoming Quiet to Unsettled thereafter (Kp 1-3).

Energetic Particles / Solar Radiation: Solar radiation was at normal background levels.

Four-Day Space Weather Forecast Summary

Solar Activity: Solar Activity is likely to be Low or Very Low, but with a slight chance of Moderate-class flares, this increasing a little when a potential far side region rotates onto the disc.

Solar Wind / Geomagnetic Activity:  Coronal hole high-speed stream influence waned through the past 24 hours, with solar wind speeds declining close to 400 km/s. Of the potentially three forecast CMEs, only one arrival has been observed so far, occurring at approximately 09/0410 UTC, considerably later than anticipated. The CME arrival has had only modest impact on the solar wind, rising to a peak near 460km/s. Should any further CME arrivals occur, they are also expected to have only limited effects, with solar wind speeds most likely continuing at Slightly Elevated levels.

Finally, a further coronal hole, CH92/+, may bring an additional high-speed stream, potentially driving solar wind speeds back above 500 km/s late on Day 3 and into Day 4 (11-12 Sep). However, this feature is not recurrent, resulting in low confidence in both the timing of arrival and the magnitude of any associated solar wind enhancement.

As a result, geomagnetic activity is expected to remain predominantly Quiet to Unsettled, with an initial slight chance of isolated Active to G1/Minor Storm intervals through Days 1-2 (09-10 Sep). Activity is then expected to increase towards the end of Day 3 (11 Sep), with Active to G1 (Minor Storm) conditions becoming possible late on 11 Sep and continuing into 12 Sep with the arrival of the CH92/+ high-speed stream.

Energetic Particles / Solar Radiation: Solar radiation is now at background, with a very slight chance of further enhancements above the S1/Minor Radiation Storm threshold.