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FXXX12 KWNP 281230

:Product: Forecast Discussion
:Issued: 2015 Aug 28 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 most complex region on the solar disk,
Region 2493 (S15W61, Fkc/beta-gamma-delta), produced several C-class
flares over the period. The largest was a C8/Sf at 28/0251 UTC. The
region exhibited slight decay in its intermediate spots and little
change in the leader and trailer over the past 24 hours. Region 2405
(S23E42, Bxo/beta) developed a few new spots but remained simple and
inactive through the period.

A CME was observed off of the west limb that first became visible on
coronagraph imagery at 26/2024 UTC. This CME appears to be associated
with a filament eruption that occurred near S09W48 between 26/1921 -
26/2047 UTC. WSA-Enlil model analysis indicated that the CME was too far
west to be geoeffective. No Earth-directed CMEs were observed.

Solar activity is expected to see a chance for M-class flares on day one
through three (28-30 Aug) and a slight chance for X-class flares over
days one and two (28-29 Aug). With the continued decay of Region 2403,
the likelihood of R-1 (Minor) or greater flares will gradually decrease.

Energetic Particle

.24 hr Summary...
The greater than 2 MeV electron flux was at normal to moderate levels
with a peak flux of 915 pfu at 27/1705 UTC. The greater than 10 MeV
proton flux was at background levels.

The greater than 2 MeV electron flux is expected to be at normal to
moderate levels with a chance for high levels on day one (28 Aug) and
increase to normal to high levels on days two and three (29-30 Aug). A
slight chance for a greater than 10 MeV proton event (S1-Minor) exists
on days one and two (28-29 Aug) due to flare potential from Region 2403
which is in a well connected magnetic position. The chance for an event
decreases on day three (30 Aug) due to a reduction in flare potential as
Region 2403 continues to show signs of decay.

Solar Wind

.24 hr Summary...
Solar wind parameters, as measured by the ACE spacecraft, were
representative of a slow moving transient. Total magnetic field strength
was enhanced between 10 and 14 nT. Wind velocities were variable around
340-380 km/s. After around 27/1620 UTC the phi angle transitioned from
positive (away) to negative (towards). Bz was predominantly oriented in
a far south configuration remained mostly between -5 nT to -10 nT for
the period.

Solar wind parameters are expected to continue at enhanced levels
through day one (28 Aug) in response to lingering CME effects and the
arrival of a co-rotating interaction region (CIR) ahead of a negative
polarity coronal hole high speed stream (CH HSS). Solar wind velocities
are expected to increase later on day one (28 Aug) and into day two (29
Aug) as the CH HSS becomes geoeffective. A gradual decrease in solar
wind parameters is expected on day three (30 Aug) as CH HSS effects
begin to wane.


.24 hr Summary...
The geomagnetic field was at active to major storm (G2-Moderate) levels
during the period due to the effects of the slow-moving 22 Aug coronal
mass ejection (CME).

Minor (G1-minor) storm conditions are expected on day one (28
Aug) due to lingering CME effects and the anticipated arrival of the CIR
and subsequent CH HSS. A decrease in activity is expected through day
one with mostly active conditions expected on day two (29 Aug) under the
influence of the coronal hole high speed stream (CH HSS). Mostly quiet
to unsettled conditions are expected by day three as the CH HSS stream
enhancement continues to decline. is the U.S. government's official web portal to all federal, state and local government web resources and services.