Routine Space Environment Product (Daily)
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316
FXXX12 KWNP 281230
DAYDIS

:Product: Forecast Discussion
:Issued: 2017 May 28 1230 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 very low. Region 2659 (13W64, Dao/beta) produced
several B-class x-ray enhancements. Minor consolidation and decay was
observed in its trailer spot. No Earth-directed CMEs were observed in
available coronagraph imagery.

.Forecast...
Solar activity is expected to continue at very low levels over the next
three days (28-30 May) with a chance for C-class flare activity.

Energetic Particle

.24 hr Summary...
The greater than 2 MeV electron flux reached high levels this period
with a peak flux of 13,200 pfu observed at 27/1535 UTC.  The greater
than 10 MeV proton flux was steady at background levels throughout the
period.

.Forecast...
The greater than 2 MeV electron flux is expected to be at normal to
moderate levels on days one (28 May) due to elevated geomagnetic field
activity associated with the arrival of the 23 May CME. High flux levels
are likely to return on days two and three (29-30 May) as CME effects
subside.

The greater than 10 MeV proton flux is expected to persist at background
levels throughout the forecast period (28-30 May).

.24 hr Summary...
Solar wind parameters were at background levels until around 27/1445 UTC
when a minor shock associated with a CME from 23 May arrived. Solar
wind speed sharply increased from around 300 km/s to around 350 km/s at
27/1445 UTC, followed by an increase to a peak value of 463 km/s at
27/2243 UTC. Through the sheath, total magnetic field strength (Bt)
ranged from 1-20 nT. (Bt) increased to a peak of around 23 nT and Bz
deflected southward reaching -15 to -20 nT during the transition into
the magnetic cloud between roughly 27/2000-2200 UTC. Afterward, a slow
taper in the strength of the magnetic cloud was observed with values for
Bt reaching 14 nT and Bz reaching near -1 nT by the end of the period.

.Forecast...
Solar wind parameters are expected to remain enhanced on day one through
midday on day two (28-29 May) under the continued influence of the 23
May CME. A slow return to near-background solar wind values are expected
late on day two through day three (29-30 May) with the return
of a nominal solar wind regime.

Geospace

.24 hr Summary...
The geomagnetic field was quiet until the 27/1500-1800 synoptic period
when the geomagnetic field became unsettled with the arrival of the 23
May CME. G2 (Moderate) geomagnetic storm levels, first observed during
the 27/2100-2400 UTC period, increased to a peak ofG3 (Strong) storm
levels for the 28/0300-0600 UTC period. Activity decreased to G2
(Moderate) and G1 (Minor) storm levels for the following two synoptic
periods. Despite relatively slow wind speeds, sustained southward Bz of
around -20 Bz provided near-optimal coupling with the Earths magnetic
field which produced the strong geomagnetic response observed during the
reporting period.

.Forecast...
The geomagnetic field is expected to reach G1 (Minor) geomagnetic storm
levels on day one (28 May) due to continued CME influence. Quiet to
active levels are expected on day day two (29 May) as effects from the
CME wane. Mostly quiet conditions are expected on day three (30 May) as
a nominal solar wind regime returns.



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