556
FXXX12 KWNP 201231
DAYDIS

:Product: Forecast Discussion
:Issued: 2024 May 20 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
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#             Forecast Discussion
#
Solar Activity

.24 hr Summary...
Solar activity reached moderate levels when Region 3685 (S13E22,
Ehi/beta-gamma) produced an M1.9/1N at 19/1344 UTC, an M2.5/1B at
19/1756 UTC, and an M1.6/1n at 19/2159 UTC. Growth was observed in the
intermediate spots of Region 3685 and the leader spots of Region 3683
(S24W65, Dai/beta). New Region 3687 (N15W06,Bxo/beta) was numbered.
Modelling of a filament eruption CME mentioned in the 19/1230 UTC
discussion suggested passage well south of the ecliptic. Analysis and
modelling are underway for a halo CME first seen in C2 imagery at
20/0536 UTC. This event is associated with a C6.7 flare at 20/0554 UTC
from AR 3683. Early estimated speeds indicate a possible arrival on 22
May.

.Forecast...
Solar activity is likely to be moderate, with isolated M-class flares
(R1-R2/Minor-Moderate) probable and a slight chance for an X-class flare
(R3/Strong or greater) on 20-22 May.

Energetic Particle

.24 hr Summary...
The 10 MeV proton flux at geosynchronous orbit had returned to
background levels. Electrons greater than 2 MeV at geosynchronous orbit
reached a peak level of 406 pfu.

.Forecast...
There is a slight chance for the greater than 10 MeV protons reaching S1
(Minor) levels on 20-22 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, with a chanced for high levels, through 21 May.

Solar Wind

.24 hr Summary...
Solar wind speeds slowly decreased from ~400-350 km/s. Total IMF
reached 9 nT at 19/1417 UTC. The maximum southward component of Bz
reached -8 nT at 19/1254Z and was mostly southward from around 19/00 UTC
to 19/19 UTC. Phi was mostly positive.

.Forecast...
Solar wind enhancements are then expected on 20 May from the CME that
left the Sun on 17 May. CME influences are expected to slowly diminish
on 21 May.  Enhanced conditions are expected on 22 May due to the
possible arrival of a halo CME from 20 May.

Geospace

.24 hr Summary...
The geomagnetic field has been at quiet to unsettled levels for the past
24 hours.

.Forecast...
On 20 May, unsettled to active levels are expected, with G1 (Minor)
storming likely with glancing CME effects from the 17 May CME. Mid to
late day on 21 May, active levels are expected to decrease to mostly
unsettled levels as CME effects gradually diminish.  G1-G3
(Minor-Strong) storm levels are possible on 22 May due to the possible
arrival of the 20 May halo CME.