From: Space Weather Prediction Center (NOAA)
Posted: Wednesday, December 12, 2012
:Product: Forecast Discussion
:Issued: 2012 Dec 12 1235 UTC
# Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center
Solar activity has been at low levels for the past 24 hours. The largest flare of the period was a C5/Sf from Region 1629 (N11W14) at 12/0727 UTC. Region 1629 has remained stable but has shown slight flux emergence in the leading spots. Region 1630 (N20W27) was responsible for a few B-class flares early in the period but has been quiet since 12/0011 UTC. This region showed signs of decay in its intermediate spots with slight growth in both the leader and follower. New Region 1631 (N20E02) was numbered overnight and has been categorized as a Bxo/beta spot group. LASCO C2 imagery has shown multiple back sided coronal mass ejections (CMEs) during the past 24 hours however none appear to be Earth-directed.
Solar activity is expected to be at very low levels with a chance for C-class flares for the next three days (13-15 Dec).
The greater than 10 MeV proton flux at geosynchronous orbit has been at background levels. The greater than 2 MeV electron flux at geosynchronous orbit has also been at background levels.
Proton and electron fluxes are expected to remain at background levels for the next three days (13-15 Dec).
Solar wind velocity, as measured by the ACE spacecraft, started the period at approximately 300 km/s and has decreased to approximately 275 km/s at the close of the period. The Total IMF reached a high of 5 nT. The Bz component hit -5 nT. At approximately 12/0700 UTC the phi angle went negative but reverted back to a positive sector two hours later.
On day one (13 Dec), a solar sector boundary (SSB) is expected to precede the arrival of a weak negative polarity coronal hole high speed stream (CH HSS). With the arrival of this CH HSS, elevated solar wind speeds ranging from 350-450 are likely. On days two and three (14-15 Dec), a return to nominal solar wind conditions is expected.
The geomagnetic field has been quiet.
The geomagnetic field is expected to be at quiet to unsettled levels on day one (13 Dec), as a negative polarity coronal hole in the northern solar hemisphere becomes geoeffective. A return to quiet levels is expected on days two and three (14-15 Dec), as effects from the CH HSS wane.
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