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FXXX12 KWNP 250031

:Product: Forecast Discussion
:Issued: 2016 May 25 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 reached low levels due to an impulsive C1/Sf flare from
Region 2546 (S07W63, Hhx/alpha) at 24/1020 UTC. The region changed
little and its magnetic gradient remained weak. The region was also the
source of a B9 flare at 24/0836 UTC and a surge of material (spray) that
ejected into space. This event was associated with a CME first seen in
SOHO/LASCO C-2 imagery at 24/0924 UTC. Due to the narrow cone of the CME
and its SW vector, it is not expected to impact Earth. New Region 2548
(N13W08, Bxo/beta) was assigned today. The region emerged as a unipolar
spot and grew into a bipolar grouping during the period. Other than a
few x-ray enhancements noted in GOES-14/SXI imagery, the region was

No Earth-directed CMEs were observed in available coronagraph imagery.

Solar activity is expected to be very low with a chance for C-class
flares all three days (25-27 May).

Energetic Particle

.24 hr Summary...
The 2 MeV electron flux was at moderate levels and reached a peak flux
of 509 pfu at 24/1320 UTC. The greater than 10 MeV proton flux remained
at background values.

The greater than 2 MeV electron flux is expected to continue at moderate
levels on day one (25 May). Normal to moderate levels are expected on
days two and three (26-27 May) due to electron redistribution from CIR
and CH HSS effects. The greater than 10 MeV proton flux is expected to
continue at background levels.

Solar Wind

.24 hr Summary...
Solar wind parameters were indicative of near-background conditions.
Solar wind speed was unsteady and variable the first half of the period
as it ranged from 380-500 km/s, before decreasing to about 400 km/s the
remainder of the period. Total IMF strength was between 3 to 5 nT, with
a brief enhancement between 24/0700-0930 UTC to 7 nT. The Bz component
of the IMF was predominantly northward, except for a prolonged period of
southward direction between 24/0730-1000 UTC. The phi angle was
primarily positive (away from Sun).

Solar wind speed is expected to continue at near ambient background
levels throughout day one (25 May). A solar sector boundary change
(SSBC) is expected to disturb the IMF as early as late on day one; more
likely day two (26 May). Following the SSBC, a weak CIR ahead of an
isolated negative polarity CH HSS is expected to further disturb the IMF
later on day two. The CH HSS is expected to rotate into a geoeffective
position by day three (27 May) and an increase in solar wind speed is


.24 hr Summary...
Geomagnetic activity was primarily quiet, but did reach unsettled levels
during the 24/0900-1200 UTC synoptic period in likely reaction to the
slightly enhanced total IMF strength and prolonged period of favorable

Geomagnetic activity is expected to be primarily quiet, with an isolated
unsettled period expected on day one (25 May) in reaction to a slightly
disturbed IMF associated with an expected SSBC. Geomagnetic response is
expected to increase on day two (26 May) with isolated unsettled to
active levels due primarily to effects from a CIR followed by the CH
HSS. Geomagnetic activity is expected to continue at quiet to active
levels on day three (27 May) due to continued effects from the CH HSS. is the U.S. government's official web portal to all federal, state and local government web resources and services.