[Propagation+Space Weather] Today's Space Weather Forecast Discussion on 2015 Jul 31 1230 UTC

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Here is the current forecast discussion on space weather and geophysical activity, issued 2015 Jul 31 1230 UTC.

Solar Activity

24 hr Summary: Solar activity remained at very low levels with a few B-class flares observed. Region 2390 (S15W60, Dai/beta) continued to decay, particularly in the intermediate portion of the region. Region 2393 (N17E40, Dao/beta) exhibited slight intermediate spot growth as it rotated further onto the visible disk. The remaining numbered regions remained stable and inactive. No Earth-directed coronal mass ejections (CME) were observed in available coronagraph imagery.

Forecast: Solar activity is expected to remain very low with a chance for C-class activity for the next three days (31 Jul-02 Aug).

Energetic Particle

24 hr Summary: The greater than 2 MeV electron flux was at normal to moderate levels with a peak flux of 825 pfu observed at 30/1440 UTC. The greater than 10 MeV proton flux remained at background levels through the period.

Forecast: The greater than 2 MeV electron flux is expected to be at normal to moderate levels on days one and two (31 Jul-01 Aug) with moderate to high levels expected on day three (02 Aug) due to high speed winds associated with a negative polarity coronal hole. The greater than 10 MeV proton flux is expected to remain at background levels (below S1-Minor).

Solar Wind

24 hr Summary: Solar wind parameters, measured at the ACE satellite, indicated a near-ambient solar wind environment early in the period. Wind speeds averaged 340 km/s, IMF total field (Bt) measured 3-5 nT, the Bz component was mostly negative to -5 nT and the phi angle was in a positive (away) sector. Shortly after 30/1300 UTC, the phi angle rotated to a negative (towards) sector. Coincident with this sector change were increases in density, temperature, Bt and a gradual increase in wind speed.

Bt increased to a maximum of 14 nT by about 30/2120 UTC while the Bz component turned further southward to -10 nT through about 31/0230 UTC when it rotated northward to +13 nT through 31/1000 UTC. Bz was then variable between +2 nT to -8 nT through periods end. Wind speed increased to about 425 km/s through about 31/0320 UTC when a further increase to about 475 km/s was observed. The period ended with wind speeds approaching 525 km/s. This solar wind enhancement was consistent with a co-rotating interaction region (CIR) in advance of an anticipated negative polarity coronal hole high speed stream (CH HSS).

Forecast: A further increase in solar wind speed is expected late on day one (31 Jul) due to CIR effects in advance of an anticipated negative polarity CH HSS. Solar wind speed parameters are expected to remain enhanced through day three (02 Aug) due to continued CH HSS influences.

Geospace

24 hr Summary: The geomagnetic field was at quiet to active levels due to CIR effects in advance of an anticipated negative polarity CH HSS.

Forecast: Mostly unsettled to active conditions, with a late period of G1 (minor) storm conditions, are expected for the remainder of day one (31 Jul). Day two (01 Aug) will see similar conditions with unsettled to active levels, with isolated G1 (minor) storm periods, as CH HSS influences continue. Mostly unsettled conditions are expected on day three (02 Aug) as CH HSS effects begin to wane.

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