356
FXXX12 KWNP 190031
DAYDIS

:Product: Forecast Discussion
:Issued: 2025 Jun 19 0030 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
# Product description and SWPC contact on the Web
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#             Forecast Discussion
#
Solar Activity

.24 hr Summary...
Solar activity was at moderate levels due to an M1.5 flare from Region
4117 (S16E63, Dai/beta); the region continues to come into better view
but foreshortening near the east limb remains, making classification of
its magnetic field difficult. Region 4114 (N18W26, Ekc/beta-gamma)
remains the largest, most complex but has become a bit more stable
throughout the period. Its trailer spot has become more symmetric and
flux emergence within its intermediate region has slowed. Region 4115
(N20W15, Eso/beta-gamma) grew in length but lost some of its interior
spots. It produced a C9.2 at 18/0313 UTC and has been quiet otherwise.

A new region is coming into better view around S13 and has produced
multiple C-class flares. Its classification is not yet able to be
determined at the time of this writing as its trailer is barely visible.
All other regions were relatively stable or in decay.

A Type II radio sweep was observed at 18/0434 UTC, velocity estimates
from radio observatories were estimated to be between 710 km/s as
recorded by the San Vito station to 1110 km/s at Palahua. The Solar
Orbiter satellite recorded a GOES approximated flare between M7 to X2 at
18/0442 UTC. A partial halo associated CME was observed in LASCO C2
imagery from just beyond the northwest limb starting around 18/0500 UTC.
Due to its location on the far-side of the Sun, impacts are not
expected.

.Forecast...
R1-R2 (Minor-Moderate) flaring is expected with a chance for X-class
flares (R3-Strong) through 21 June, mostly driven by Regions 4114, 4115,
and 4117.

Energetic Particle

.24 hr Summary...
Due to continued influence from the coronal hole (CH) high speed stream
(HSS), the greater than 2 MeV electron flux on the GOES-19 satellite
remained elevated. The flux neared the 1000 pfu threshold but did not
cross during its respective diurnal maxima.

The aforementioned CME was expected to produce an S1 (Minor) event but
has yet to materialize and the greater than 10 MeV proton flux was at
background levels.

.Forecast...
The greater than 2 MeV electron flux will continue to near the 1000 pfu
threshold during the diurnal maxima due to continue CH influence through
20 Jun with waning influences on 21 Jun. The greater than 10 MeV
electron flux is expected to remain at background barring any
significant flares. There remains a slight possibility for protons to
become elevated due to the CME on the far-side but confidence is low.

Solar Wind

.24 hr Summary...
Solar wind parameters continued to reflect a positive polarity CH HSS
regime. Total field (Bt) remained around 7-9 nT with the north-south
(Bz) component oscillating between +/-8 nT. Solar wind speeds
primarily averaged 480-500 km/s. Phi angle was predominantly in the
positive (away from the Sun) orientation.

.Forecast...
CH HSS conditions are expected to persist through 20 Jun with waning
influences into 21 Jun. There is a slight chance for an enhancement of
solar wind parameters 20 Jun due to a CME interplanetary shock
associated with a C5.5 flare at 17/0813 UTC from Region 4115. The mag
cloud is diffuse with model density and wind profiles showing weak
signatures upon arrival.

Geospace

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

.Forecast...
Quiet to active conditions are expected to persist into 19 Jun due to
continued CH HSS effects. Minor (G1) geomagnetic storming is likely on
20 June due to any glancing influences from the aforementioned CME that
left the Sun early on 17 June UTC day. Unsettled conditions are expected
to continue in 21 Jun.

-Bri