[Propagation+Space Weather] Today's Space Weather Forecast Discussion on 2015 Apr 18 1230 UTC

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Here is the current forecast discussion on space weather and geophysical activity, issued 2015 Apr 18 1230 UTC.

Solar Activity

24 hr Summary: Solar activity was low. Region 2325 (N04E24, Dai/beta) produced a C1/Sf flare at 17/1237 UTC and Region 2324 (N19E16, Cki/beta) produced a C1/Sf flare at 17/1801 UTC, which were the largest events of the period. Regions 2324, 2325, and 2327 (S10E63, Cso/beta) were relatively stable throughout the period while Regions 2321 (N11W15, Ekc/beta-gamma) and 2326 (N15W09, Cri/beta) were in decay.

A filament eruption centered near N27W56 was observed in SDO/AIA imagery between 17/1430-18/0345 UTC, but this event was not reflected in SOHO/LASCO coronagraph imagery suggesting that the filament was likely reabsorbed.

A coronal mass ejection was observed in SOHO/LASCO C2 coronagraph imagery beginning at 18/0312 UTC off the north-northeast disk but lacking any discernible events on the visible disk that match the time and location of the CME, this event is likely associated with activity on the far-side of the Sun. No Earth-directed coronal mass ejections (CMEs) were observed.

Forecast: Solar activity is expected to be low with a slight chance for M-class (R1-Minor) flare activity for the next three days (18-20 Apr).

Energetic Particle

24 hr Summary: The greater than 2 MeV electron flux was at moderate to high levels, reaching a peak flux of 2,090 pfu at 17/1815 UTC. 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 moderate to high levels over the next three days (18-20 Apr). The greater than 10 MeV proton flux is expected to remain at background levels over the next three days (18-20 Apr).

Solar Wind

24 hr Summary: Solar wind parameters were indicative of the waning influence of a negative polarity southern polar connected coronal hole high speed stream (CH HSS). Solar wind velocities steadily decreased from initial values near 675 km/s to end-of-period values near 550 km/s. IMF total field values were steady between 2-4 nT and Bz reached a maximum southward component of -3 nT late in the period. The phi angle was generally steady in a negative (toward the Sun) solar sector orientation throughout the period.

Forecast: Solar wind parameters are expected to continue a steady return to background levels over days one and two (18-19 Apr). Solar wind parameters are expected to become enhanced once again on day three (20 Apr) as a recurrent positive polarity CH HSS becomes geoeffective.

Geospace

24 hr Summary: The geomagnetic field was quiet to unsettled under a nominal solar wind regime.

Forecast: The geomagnetic field is expected to persist at quiet to unsettled levels on days one and two (18-19 Apr) with quiet to active conditions expected on day three (20 Apr) due to the influence of a positive polarity CH HSS.

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