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FXXX12 KWNP 261231

:Product: Forecast Discussion
:Issued: 2015 Apr 26 1230 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
# Product description and SWPC contact on the Web
#             Forecast Discussion
Solar Activity

.24 hr Summary...
Solar activity was low.  The largest event of the period was a
long-duration C1 flare at 25/1849 UTC that was associated with activity
on the northwest limb.  Shortly after the flare, the associated coronal
mass ejection (CME) was first observed in SOHO/LASCO C2 coronagraph
imagery at 25/181836 UTC but was not Earth-directed.  An asymmetrical
partial-halo CME was observed in coronagraph imagery beginning at
25/1448 UTC but was associated with solar activity on the far-side of
the Sun and was not Earth-directed.

Region 2331 (S09W54, Dai/beta-gamma) began to show signs of decay and
magnetic simplification this period, but remains the most complex region
on the visible disk.  The remaining three active regions on the disk
were stable throughout the period.  No Earth-directed CMEs were

Solar activity is expected to be low with a slight chance for M-class
(R1-Minor) flare activity over the next three days (26-28 Apr).

Energetic Particle

.24 hr Summary...
The greater than 2 MeV electron flux was at moderate to high levels and
reached a peak flux value of 1,310 pfu at 25/1530 UTC.  The greater than
10 MeV proton flux was slightly elevated this period but remained well
below event thresholds.

The greater than 2 MeV electron flux is expected to persist at moderate
to high levels over the next three days (26-28 Apr).  The greater than
10 MeV proton flux is expected to return to background levels on day one
(26 Apr) and remain there for days two and three (27-28 Apr).

Solar Wind

.24 hr Summary...
Solar wind parameters were at background levels this period.  Solar wind
velocity decreased from initial values near 335 km/s to end-of-period
values near 300 km/s.  IMF total field values were steady between 2-4 nT
and Bz was mostly positive throughout the period.  The phi angle
remained steady in a positive (away from the Sun) solar sector

Solar wind parameters are expected to remain at background levels over
the next three days (26-28 Apr) with a minor perturbation possible on
day three due to a solar sector boundary crossing.


.24 hr Summary...
The geomagnetic field was exceedingly quiet under a nominal solar wind

The geomagnetic field is expected to persist at quiet levels on days one
and two (26-27 Apr) with quiet to unsettled levels likely on day three
(28 Apr) due to a solar sector boundary crossing. is the U.S. government's official web portal to all federal, state and local government web resources and services.