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Routine Space Environment Product (Daily)
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000
FXXX12 KWNP 250030
DAYDIS

:Product: Forecast Discussion
:Issued: 2013 May 25 0030 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
# Product description and SWPC contact on the Web
# http://www.swpc.noaa.gov/wwire.html
#
#             Forecast Discussion
#
Solar Activity

.24 hr Summary...
Solar activity was at low levels.  The largest flares of the period were
a C2 flare at 24/0124 UTC from an as yet unnumbered region just around
the southeast limb and a C2/Sn at 24/1635 UTC from Region 1756 (S20E15,
Ehi/beta-gamma).  Some separation was observed between the intermediate
and trailing spots of Region 1756.  Slight decay was observed in the
trailing spots of Region 1755 (N11E26, Dai/beta-gamma).  Slight growth
was observed in Region 1748 (N12W69, Cro/beta).  X-ray background levels
have declined slowly over the period.  No Earth-directed coronal mass
ejections (CMEs) were observed during the period.

.Forecast...
Solar activity is expected to be low with a chance for M-class
(R1-Minor) flares for the forecast period (25-27 May).

Energetic Particle

.24 hr Summary...
The greater than 2 MeV electron flux at geosynchronous orbit was at high
levels.  Electron flux data appears to have normalized by 24/0600 UTC.
The greater than 10 MeV proton event above the 100 pfu (S2-Moderate)
levels began at 22/1730 UTC, reached a peak flux of 1660 pfu at 23/0650
UTC, and ended at 24/0435 UTC.  Proton flux levels continued to persist
above the 10 pfu (S1-Minor) level during the period.

.Forecast...
The greater than 2 MeV electron flux at geosynchronous orbit is expected
to continue at moderate to high levels for the forecast period (25-27
May) due to CME activity.  The greater than 10 MeV proton flux at
geosynchronous orbit is likely to continue above the 10 pfu threshold
(S1-Minor) through early on day 1 (25 May).  There is a chance for a
proton event on day 2 (26 May) and a slight chance for day 3 (27 May).

Solar Wind

.24 hr Summary...
Solar wind speed, measured at the ACE spacecraft, ranged between 380
km/s and 540 km/s with total field measurements between 3 nT and 8 nT
for the majority of the period.  At 24/1735 UTC, a shock was observed in
ACE data associated with the 22 May CME.  Solar wind speed increased
from approximately 440 km/s to 560 km/s while the total field increased
from 6 nT to 15 nT.  The Bz component fluctuated between +12 nT and -14
nT.  Shortly after, total field measurements became variable between 4
nT and 14 nT while the solar wind speed averaged near 580 km/s through
the end of the period.  Phi angle was consistently negative (towards)
during the period.

.Forecast...
Solar wind speed is expected to remain enhanced for the period (25-27
May) due to a combination of waning CME effects and coronal hole high
speed stream (CH HSS) activity.

Geospace

.24 hr Summary...
The geomagnetic field was at quiet to minor storm levels.  Quiet to
unsettled conditions persisted until the end of the 24/1800 UTC period.
At 24/1812 UTC, a geomagnetic sudden impulse (18 nT) was observed in the
Boulder magnetometer as a result of the arrival of the 22 May CME.  The
geomagnetic field increased to minor storming (G1-Minor) during the
24/1800-2100 UTC period.  Active levels continued through the end of the
period.

.Forecast...
The geomagnetic field is expected to be at quiet to active levels with a
chance for periods of minor storming on day 1 (25 May) as CME effects
decrease.  Quiet to unsettled levels are expected on days 2-3 (26-27
May) due to CH HSS activity.
National Weather Service Weather Forecast Office
