476
FXXX12 KWNP 181231
DAYDIS

:Product: Forecast Discussion
:Issued: 2024 May 18 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 reached high levels following an M7.2/2b flare from
Region 3685 (S13E49, Esi/beta-gamma). Associated with the flare was Type
II (425 km/s) and Type IV radio sweeps as well as a CME first observed
in SOHO/LASCO C2 imagery at 17/2124 UTC off the E limb. Initial analysis
indicated a potential glancing blow late on 20 May. Slight growth was
observed in Region 3685 and Region 3683 (S23W39, Dri/beta). The rest of
the spotted regions were either stable or slightly decaying.

.Forecast...
Solar activity is expected to be low with a good chance for further
M-class flares (R1-R2/Minor-Moderate) and a slight chance for an X-class
flare (R3/Strong or greater) on 18-20 May.

Energetic Particle

.24 hr Summary...
The greater than 10 MeV proton flux was slightly elevated, but well
below S1 (Minor) levels. The 2 MeV electron flux was at normal to
moderate levels.

.Forecast...
There is a slight chance for the greater than 10 MeV protons reaching S1
(Minor) levels on 18-20 May due to the flare potential of Region 3685.
The greater than 2 MeV electron flux is expected to remain at normal to
moderate levels through 20 May.

Solar Wind

.24 hr Summary...
Solar wind parameters reflected the likely arrival of the 14 May CME.
The arrival at 17/1245 UTC resulted in stronger enhancements than
anticipated, with total field reaching a peak of 17 nT, Bz seeing a
maximum southward deflection of -15 nT, and solar wind speeds mostly in
the 450-500 km/s range. After 18/0000 UTC, solar wind speed began to
decrease to the 400-450 km/s range and total field decreased to under 10
nT after 18/0600 UTC. Phi angle was mostly negative.

.Forecast...
Solar wind parameters should continue to decrease through the rest of 18
May. Further enhancements are likely on 19-20 May, due to glancing
influences of additional CMEs.

Geospace

.24 hr Summary...
The geomagnetic field reached G1-G2 (Minor-Moderate) storm levels late
on 17 May following the arrival of the anticipated 14 May CME. Quiet to
active levels were observed through early on 18 May.

.Forecast...
The latter half of 18 May should see a return to quiet to unsettled
levels as CME effects diminish. By 19-20 May, conditions are expected to
increase back to unsettled to active levels, with a chance for G1
(Minor) storming, due to glancing CME effects from the 15 and 17 May
CMEs.