[Propagation+Space Weather] Today's Space Weather Forecast Discussion on 2015 Aug 26 1230 UTC

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Here is the current forecast discussion on space weather and geophysical activity, issued 2015 Aug 26 1230 UTC.

Solar Activity

24 hr Summary: Solar activity dropped to low levels over the period. Region 2403 (S15W37, Fki/beta-gamma-delta) produced numerous C-class flares, the largest being a C2/1f at 25/2353 UTC. The region was relatively stable in growth during the period and stretched further E-W with no apparent strengthening of the regions overall magnetic field structure. Despite retaining a complex delta classification, analysis of available magnetograms showed the magnetic shear has weakened. Despite the dissipation, the region remains capable of higher levels of activity due to possible and imperceptible magnetic field line tension. Region 2404 decayed into a plage region and remained void of reportable solar activity.

A CME off of the southwest limb, first visible on LASCO coronagraph imagery at 25/1325 UTC, is undergoing further forecaster analysis and WSA/Enlil modeling to determine if it has an Earthward trajectory.

Forecast: Solar activity is expected to continue at low levels, with M-class flares (R1-R2, Minor-Moderate) likely and a slight chance for X-class (R3, Strong or greater) on days one and two (26-27 Aug), due to the continued flare potential of Region 2403. Activity is expected to continue at low levels into day three (28 Aug) with a chance for M-class flares, but a diminished chance of X-class flares as Region 2403 decays further.

Energetic Particle

24 hr Summary: The greater than 2 MeV electron flux reached high levels with a peak flux of 1837 pfu at 25/1700 UTC. The greater than 10 MeV proton flux remained at background levels.

Forecast: The greater than 2 MeV electron flux is expected to continue at normal to high levels on day one (26 Aug) and decrease down to normal to moderate levels on days two and three (27-28 Aug). The greater than 2 MeV proton flux is expected to continue at background levels for all three days, but with a slight chance for an S1 (Minor) solar radiation storm on days one and two (26-27 Aug) due to the flare potential and more Earth-aligned position of Region 2403 as it rotates further west. The slight chance for solar radiation storms is expected to diminish by day three (28 Aug) as Region 2403 continues to decay and flare potential decreases further.

Solar Wind

24 hr Summary: Solar wind parameters as measured by the ACE spacecraft indicated a return to an ambient space weather environment. Solar wind velocities remained steady at around 400-420. The total interplanetary magnetic field (IMF) strength began the period primarily between 3-4 nT and increased gradually to around 9 nT as the period progressed. The Bz component was primarily southward at around -3 nT to -5 nT, but reached a maximum southward deflection near -8 nT near the end of the period. The phi angle was primarily positive (away) with a few short deflections to the negative (towards) sector.

Forecast: Solar wind parameters are expected to remain at slightly elevated levels on day one (26 Aug). Solar wind velocity and IMF strength are expected to increase as a trans-equatorial, negative polarity coronal hole high speed stream (CH HSS), preceded by a co-rotating interaction region (CIR), rotates into a geoeffective position late on day two and on into day three (27-28 Aug).

Geospace

24 hr Summary: The geomagnetic field started the period at quiet to unsettled levels. The last two periods saw active conditions due to the prolonged periods of southward Bz.

Forecast: G1 (Minor) storm conditions are expected on day one (26 Aug) due to the slightly enhanced IMF and periods of sustained -Bz. Quiet to unsettled conditions are expected to begin day two (27 Aug), until late in the period when the potential CIR ahead of the CH HSS is expected to arrive at Earth, likely resulting in active conditions. Active conditions are expected to continue into day three (28 Aug) as the CH HSS becomes geoeffective.

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