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FXXX12 KWNP 280030

:Product: Forecast Discussion
:Issued: 2015 May 28 0030 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. A single C1 flare was observed from the
southeast limb. Some new spot regions rotated onto the visible disk in
the northeast (N11E69, N13E58) and southeast [S11E66) and are being
monitored for potential numbering.  There are three large filaments on
the visible disk that bear watching.

A type-II radio sweep (Est. 493 km/s) was reported at 27/1234 UTC, with
no associated significant X-ray event. Once SOHO/LASCO coronagraph
imagery became available, a CME was observed erupting from the northeast
limb at 27/1325 UTC.  This event appeared to be correlated with an
eruption on SDO/AIA 193 imagery on the northeast limb and is not
expected to be geoeffective.

Solar activity is expected to be at very low levels with a growing
chance for C-class activity over the next three days (28-30 May). Day
three is also forecast to have a slight change for a M-class (R1-minor)
solar flare event, as old region 2339 is expected to return to the
visible disk.

Energetic Particle

.24 hr Summary...
The greater than 2 MeV electron flux was at normal background levels
while the greater than 10 MeV proton flux remained at background levels
this period.

The greater than 2 MeV electron flux is expected to be at predominately
normal background levels over the next three days (28-30 May), with an
increasing chance of moderate levels due to elevated solar winds from a
a high speed solar wind stream. The greater than 10 MeV proton flux is
expected to remain at background levels throughout the forecast period.

Solar Wind

.24 hr Summary...
Solar wind parameters, measured at the ACE spacecraft, indicated a
continued ambient wind environment. Solar wind speed was between 300 and
320 km/s. Total magnetic field strength was about 7 nT while the Bz
component mostly varied between -5 to +5 nT. The phi angle switched
several times between a negative (toward) to a positive (away)
orientation, and back, throughout the period.

An equatorial, positive polarity coronal hole high speed stream (CH HSS)
moves into a geoeffective position over the next three days (28-30 May),
bringing enhanced solar wind conditions. Peak solar wind speed is
forecast near 500 km/s and the brunt of the effects are expected on day


.24 hr Summary...
The geomagnetic field remained at quiet to unsettled levels.

The geomagnetic field is expected to persist at quiet to unsettled
conditions on day one (28 May) as an equatorial, positive polarity CH
HSS moves into a geoeffective position. By day two (29 May) active
conditions are possible. Day three is forecast to see a return of quiet
to unsettled levels, as CH HSS effects begin to wane. is the U.S. government's official web portal to all federal, state and local government web resources and services.