[Propagation+Space Weather] Today's Space Weather Forecast Discussion on 2015 Apr 27 1230 UTC

[nw7us@sunspotwatch.com]

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Here is the current forecast discussion on space weather and geophysical activity, issued 2015 Apr 27 1230 UTC.

Solar Activity

24 hr Summary: Solar activity was low. Region 2331 (S10W66, Dao/beta) produced a C1 flare at 26/2057 UTC which was the largest event of the period. This event was associated with a pair of disappearing solar filaments (DSF), followed by coronal dimming and a surge of ejecta to the southwest as observed in SDO/AIA 193 imagery. The first DSF was centered near S15W61 with an extent of 4 degrees and the second DSF was centered near S17W35 with an extent of about 8 degrees. An associated coronal mass ejection (CME) became visible off the southwest in SOHO/LASCO C2 coronagraph imagery beginning at 26/2336 UTC. Forecaster analysis and WSA-Enlil model output suggests a weak glancing blow arrival late on 30 April.

Region 2331 continued to decay this period, especially in its intermediate and trailer spot areas, and decreased in magnetic complexity. Region 2327 (S08W56, Cao/beta) was stable while Region 2333 (N20E05, Hrx/alpha) decayed rapidly over the past 12 hours.

Forecast: Solar activity is likely to be low over the next three days (27-29 Apr).

Energetic Particle

24 hr Summary: The greater than 2 MeV electron flux was at moderate to high levels this period, reaching a peak flux value of 1,340 pfu at 26/1505 UTC. The greater than 10 MeV proton flux was at near-background levels throughout the period.

Forecast: The greater than 2 MeV electron flux is expected to continue at moderate to high levels over the next three days (27-29 Apr). The greater than 10 MeV proton flux is expected to persist at background levels throughout the forecast period.

Solar Wind

24 hr Summary: Solar wind parameters were at background levels throughout the period. Solar wind velocity varied between 300-350 km/s. IMF total field strength values slowly increased from initial values near 1 nT to 7 nT late in the period and Bz was generally positive until 27/0700 UTC when Bz reached -5 nT. The phi angle was predominately positive (away from the Sun) with brief transitions to a negative (toward) solar sector. Forecast: Solar wind parameters are expected to remain at background levels over the next three days (27-29 Apr) with a minor perturbation possible on day three ahead of a positive polarity coronal hole high speed stream (CH HSS).

Geospace

24 hr Summary: The geomagnetic field was quiet under an ambient solar wind environment.

Forecast: The geomagnetic field is expected to remain at quiet levels on days one and two (27-28 Apr) with quiet to unsettled levels likely on day three (29 Apr) due to a possible enhancement of solar wind parameters ahead of a positive polarity CH HSS.

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