[Propagation+Space Weather] Today's Space Weather Forecast Discussion on 2015 Jul 20 1230 UTC

[nw7us@sunspotwatch.com]

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Here is the current forecast discussion on space weather and geophysical activity, issued 2015 Jul 20 1230 UTC.

Solar Activity

24 hr Summary: Solar activity was at low levels at the beginning of the period due to a long duration C2 flare at 19/1040 UTC associated with a filament eruption located in the SW quadrant centered near S32W52. WSA/ENLIL analysis of the associated CME (first observed in SOHO/LASCO C2 imagery at 19/0948 UTC) shows a possible weak glancing blow from the northern flank arriving early on 23 Jul. Another filament eruption in the NW quadrant occurred between 20/0700 and 20/0845 UTC in SDO/AIA 304 imagery. Further analysis of this eruption is pending as coronagraph imagery becomes available.

Slight growth was observed in the intermediate spots of Region 2387 (N17E11, Dai/beta). The rest of the spotted regions were relatively stable. No further C-class flaring was observed during the period.

Forecast: Solar activity is expected to be very low with a chance for C-class flares, and a slight chance for an M-class (R1-Minor) event, over the next three days (20-22 Jul), particularly from Region 2387.

Energetic Particle

24 hr Summary: The greater than 2 MeV electron flux reached high levels with a maximum flux of 7860 pfu observed at 19/1755 UTC. The greater than 10 MeV proton flux remained at background levels throughout the period.

Forecast: The greater than 2 MeV electron flux at geosynchronous orbit is expected to be at moderate to high levels for the forecast period (20-22 Jul) while 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 continued at nominal levels over the period. Solar wind speed ranged from 264 km/s to 304 km/s. An increase in total field occurred from a low of 2 nT to 6 nT. As the increase was observed during the second half of the period, the Bz component deflected southward after 20/0300 UTC and remained so reaching a maximum of -6 nT. Phi angle was oriented in a positive (away) sector.

Forecast: A trans-equatorial, positive polarity coronal hole high speed stream (CH HSS) is expected to become geoeffective by mid to late on day one (20 Jul) and persist through early on day two (21 Jul) with a slight enhancement in solar wind parameters. A return to nominal conditions are expected by day three (22 Jul).

Geospace

24 hr Summary: The geomagnetic field was at quiet levels.

Forecast: The geomagnetic field is expected to increase to quiet to unsettled levels by late on day one (20 Jul) as a positive polarity CH HSS becomes geoeffective. Quiet to unsettled conditions are expected to persist into day two (21 Jul). By day three (22 Jul), a return to mostly quiet conditions is expected.

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