[Propagation+Space Weather] Today's Space Weather Forecast Discussion on 2016 May 21 1230 UTC

[nw7us@sunspotwatch.com]

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Here is the current forecast discussion on space weather and geophysical activity, issued 2016 May 21 1230 UTC.

Solar Activity

24 hr Summary: Solar activity was very low and only background flare activity was observed this period. Region 2547 (S17W49) decayed to plage and Region 2546 (S07W14, Cho/beta) underwent minor spot development late in the period. No Earth-directed coronal mass ejections (CMEs) were observed in available coronagraph imagery. Forecast: Solar activity is expected to remain at very low levels with a chance for C-class flare activity over the next three days (21-23 May).

Energetic Particle

24 hr Summary: The greater than 2 MeV electron flux was at normal to moderate levels and the greater than 10 MeV proton flux was at background levels throughout the period.

Forecast: The greater than 2 MeV electron flux is expected to be at normal to moderate levels with a chance for high levels throughout the forecast period (21-23 May).

The greater than 10 MeV proton flux is expected to remain at background levels throughout the forecast period.

Solar Wind

24 hr Summary: Solar wind parameters reflected the continued influence of a positive polarity coronal hole high speed stream (CH HSS). Solar wind speeds slowly increased from initial values near 400 km/s to a peak of around 525 km/s late in the period. Bt values ranged between 1-10 nT and a period of sustained southward Bz was observed between 21/0500-0800 UTC. The phi angle was generally stable in a positive (away) solar sector orientation with brief transitions to a negative sector observed between 21/0100-0600 UTC.

Forecast: The geomagnetic field is expected to remain slightly enhanced until late on day one (21 May) when an additional solar wind enhancement is expected as the southern-most extension of the positive polarity CH HSS moves into a geoeffective position. Solar wind speeds are likely to increase to 450-550 km/s late on day one (21 May) through midday on day two (22 May) before slowly returning to near-background levels by day three (23 May).

Geospace

24 hr Summary: The geomagnetic field was generally quiet to unsettled through most of the period but reached minor (G1) geomagnetic storm levels between 21/0600-0900 UTC due to continued CH HSS influence and prolonged southward Bz.

Forecast: Minor (G1) geomagnetic storms early on day one (21 May) are expected to decrease to quiet to unsettled levels until late in the period. Active conditions are expected late on day one (21 May) through early on day two (22 May) as the southern-most extension of the positive polarity CH HSS moves into a geoeffective position. Unsettled levels are expected for the latter half of day two and early on day three (22-23 May) followed by mostly quiet conditions for the remainder of day three (23 May) as CH HSS influences weakens and subsides.

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