:Product: Forecast Discussion
:Issued: 2022 May 18 1230 UTC
# Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center
#
Solar Activity

.24 hr Summary...
Solar activity was low with numerous, low-level C-class flares. Region
3010 (S15E04, Cao/Beta) continued to exhibit decay in both leading and
trailing spots while Region 3011 (N18, L=129) decayed to plage. Region
3014 (N21E23, Dki/Beta-Gamma) remained the most magnetically complex of
the 7 active regions inhabiting the solar disk, and was responsible for
some of the aforementioned low-level C-class flare activity throughout
the period. The remaining active regions were little changed and were
otherwise unremarkable outside of the occasional C1/C2 flare.

The relatively small CME observed in SOHO-NASA coronagraph imagery
around 17/0548 UTC that was mentioned in the previous discussion has
been modeled and analyzed. However, confidence is low as to the accuracy
of the results as no clear source region has been identified.
Furthermore, this is compounded by the lack of a clear profile signature
of the CME being readily apparent in NASA STEREO-A COR2 images. With
that said, this event is not likely to be on the Sun-Earth line, but if
there is any Earth-directed component it would arrive on 20 May.

.Forecast...
Low solar activity is expected to continue, with a chance for M-class
flares (R1-R2; Minor-Moderate radio blackouts) and slight chance for
X-class activity (R3; Strong) 18-20 May.

Energetic Particle

.24 hr Summary...
The greater than 2 MeV electron flux was normal to moderate and the
greater than 10 MeV proton flux remained at background.

.Forecast...
The greater than 2 MeV electron flux is expected to be mainly moderate
18-20 May, with a chance for high levels 18-19 May due to CH HSS
influences. The greater than 10 MeV proton flux is expected to continue
at background values.

Solar Wind

.24 hr Summary...
Solar wind parameters were indicative of weakening positive polarity CH
HSS influences. Total IMF strength was primarily 3-5 nT and Bz component
was benign with no pronounced southward deflections. Solar wind speed
decreased from peaks of ~600 km/s to ~485 km/s near the end of the
period. The phi angle was predominantly positive.

.Forecast...
Positive polarity CH HSS influences are expected to continue influencing
the solar wind field 18-20 May as current Earth-connection to a CH HSS
continues 18 May, followed by another positive polarity CH HSS
connection as early as 19 May. Further enhancements are possible 20 May
given any, however unlikely, Earth-directed component influence from the
17 May CME.

Geospace

.24 hr Summary...
The geomagnetic field was quiet to unsettled in response to the varied
CH HSS effects.

.Forecast...
The geomagnetic field is expected to remain quiet to unsettled with a
chance for isolated active periods 18 May as current CH HSS effects
continue, but weaken. Unsettled to active conditions are expected 19-20
May as the next CH HSS becomes geoeffective. Additionally, any potential
effects related to the possible nearby CME passage could contribute to
any elevated responses on 20 May.