Routine Space Environment Product (Daily)
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FXXX12 KWNP 280031

:Product: Forecast Discussion
:Issued: 2017 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 very low.  Region 2659 (N13W57, Dai/beta) produced a
long-duration B9 flare at 27/1830 UTC and began to show signs of decay.
No Earth-directed CMEs were observed in available coronagraph imagery.

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

The greater than 2 MeV electron flux is expected to be at 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
expected to return on days two and three (29-30 May) as CME effects

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 sudden impulse 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.  Following the sudden impulse, total field strength values
increased to a peak of around 23 nT and Bz deflected southward reaching
-15 to -20 nT late in the period.  Following CME arrival the solar wind
density peaked at 68 particles/cubic cm and the phi angle became highly

Solar wind parameters are expected to remain elevated 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.


.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 were observed during
the 27/2100-2400 UTC period as the Bz component deflected southward near
-20 nT for an extended period of time.

The geomagnetic field is expected to be at unsettled to G2 (Moderate)
geomagnetic storm levels early on day one (28 May) due to continued CME
influence.  Quiet to unsettled levels are expected after midday on day
one through day two (28-29 May) as CME effects diminish.  Generally
quiet conditions are expected on day three (30 May) with the return of a
nominal solar wind regime. is the U.S. government's official web portal to all federal, state and local government web resources and services.