[Propagation+Space Weather] Today's Space Weather Forecast Discussion on 2015 Oct 02 1230 UTC

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Here is the current forecast discussion on space weather and geophysical activity, issued 2015 Oct 02 1230 UTC.

Solar Activity

24 hr Summary: Solar activity reached high levels during the period as Region 2422 (S20W77, Fkc/beta-gamma-delta) produced an M5/1n flare at 02/0012 UTC, as well as an impulsive M4/Sn flare at 01/1310 UTC. The region appeared to exhibit slight decay as it rotated closer to the limb, decreasing slightly in areal coverage, while retaining its delta magnetic configuration. Neither of the M-class flares had associated radio signatures that would suggest an associated coronal mass ejection (CME), and no obvious CMEs were noted in LASCO coronagraph imagery that would be attributed to the M-flares. Region 2427 (N18W11, Cai/beta) displayed signs of decay in its trailer spots and remained in a simple bipolar configuration. Region 2420 (N12W78, Hsx/alpha) decayed further but did produce an optical subflare.

Analysis was completed regarding the CME events from 30 Sep. Multiple model runs were submitted and at least a few of the returned products indicate a possible, partial Earth-directed event. Other model returns indicate a glancing blow and even near-miss events. Confidence factor amongst these results is not high, however, it seems probable that at least a glancing blow is likely and will be reflected in the geomagnetic activity forecast.

Forecast: Solar activity is expected to be low with moderate (R1-R2, Minor-Moderate) flare activity likely on days one and two (02-03 Oct). There is a chance for X-class (R3, Strong or greater) flares on day one, but decreasing to a slight chance on day two due to the flare potential and location of Region 2422. There is a chance for M-class activity and slight chance for X-class flares on day three (4 Oct) as Region 2422 undergoes decay and the eastern-most portion of the region rotates to and beyond the limb.

Energetic Particle

24 hr Summary: The greater than 2 MeV electron flux was at normal levels during the period. The greater than 10 MeV proton flux returned to background values.

Forecast: The greater than 2 MeV electron flux is expected continue at normal to moderate levels on days one and two (02-03 Oct) and possibly reach normal to high levels on day three (04 Oct) due to coronal hole high speed stream (CH HSS). The greater than 10 MeV proton flux is expected to remain at background levels, with a chance of reaching 10 pfu or greater levels (S1 or higher) due to the increasingly geoeffective positioning of Region 2422, as well as possible increases associated with accelerated particles ahead of a CME from the 30 Sep events.

Solar Wind

24 hr Summary: Solar wind parameters remained slightly enhanced throughout the period. Solar wind velocity began the period near 320 km/s but steadily increased to near 360 km/s by 01/1700 UTC. Just after 02/0400 UTC, velocities did increase briefly to just over 400 km/s, but have since returned to near 350 km/s. Total field strength remained steady between 6 nT and 12 nT for most of the period, while the Bz component was variable between -10 nT and +8 nT. The phi angle began the period in a predominantly negative (towards the Sun) orientation, but experienced a Solar Sector Boundary Crossing (SSBC) into a mostly positive (away from the Sun) sector just after 01/2300 UTC.

Forecast: Solar wind speeds are expected to remain slightly enhanced on day one (02 Oct) as Earth lies along the edge of the heliospheric current sheet. Conditions are expected to remain enhanced into day two (03 Oct) as a positive polarity CH HSS is expected to influence the space environment, along with the potential arrival of a CME from the 30 Sep events. Further enhancements are expected to disturb the solar wind environment into day three (04 Oct).

Geospace

24 hr Summary: The geomagnetic field was at unsettled to active levels throughout the period.

Forecast: The geomagnetic field is expected to remain at unsettled to active levels, with periods of minor storming (G1-Minor) likely on day one (02 Oct), due to enhanced solar wind parameters. The geomagnetic field is expected to remain at unsettled to active levels into day two (03 Oct), with periods of minor (G1-Minor) storming likely late in the day, due to the possible arrival of a CME from the 30 Sep events. Conditions are likely to continue at unsettled to minor storming levels on day three (04 Oct) due to CME effects.

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