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FXXX12 KWNP 270031

:Product: Forecast Discussion
:Issued: 2016 May 27 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 a pair of C-class flares.
Region 2548 (N13W36, Dso/beta) grew in area, in particular the leading
penumbral spot areal coverage. While the regions overall magnetic
gradient remained relatively minor, some shear developed within the
region. This instability likely contributed to the regions C1/Sf flare
at 26/1336 UTC and subsequent B-class flares. A C1 flare erupted from
Region 2546 (S07W88, Hhx/alpha) at 26/1351 UTC with an associated Type
IV radio sweep first detected at 26/1359 UTC. The flare was associated
with a narrow cone CME, but due to a gap in SOHO/LASCO-C2 imagery, the
CME was not first observed until 26/1612 UTC. Analysis suggested the CME
was not Earth-directed.

Due to the growth in Region 2548 and the recent C-class flares from
Regions 2546 and 2548, solar activity is likely to be low on days one
and two (27-28 May). Solar activity is expected to be very low, with a
chance for C-class flares on day three (29 May) as Region 2546 rotates
well beyond the west limb.

Energetic Particle

.24 hr Summary...
The greater than 2 MeV electron flux was at moderate levels and the
greater than 10 MeV proton flux continued at background values.

The greater than 2 MeV electron flux is expected to be at normal to
moderate levels on days one through three (27-29 May) due to electron
redistribution associated with CH HSS effects.

Solar Wind

.24 hr Summary...
Solar wind parameters were indicative of ambient background conditions,
with possible indications of a pending solar sector boundary crossing
(SSBC) and CIR later in the period. Solar wind speed ranged from about
325-370 km/s. Particle density steadily rose after 26/1400 UTC. Total
IMF strength ranged primarily from 2 to 5 nT; while the Bz component
underwent only weak deviations. The phi angle was positive (away from
Sun) most of the period before rotating briefly into a negative sector
(towards the Sun) between about 26/1615-1730 UTC.

Solar wind parameters are expected to become enhanced due to an expected
SSBC, followed by a weak CIR and connection to an isolated, negative
polarity CH HSS on day one (27 May). Solar winds are expected to
diminish slightly on day two (28 May). Solar wind parameters are
expected to become disturbed again on day three (29 May) due to another
approaching negative polarity CH HSS.


.24 hr Summary...
The geomagnetic field was quiet.

The geomagnetic field is expected to be quiet to unsettled with an
isolated active period likely on day one (27 May) due to CIR and CH HSS
effects. Quiet to unsettled conditions are expected on day two (28 May)
due to waning CH HSS effects. The geomagnetic response on day three (29
May) is expected to be mostly quiet to unsettled with active periods
late in the day due to another negative polarity CH HSS. is the U.S. government's official web portal to all federal, state and local government web resources and services.