<AUR>.Forecast Discussion

:Product: Forecast Discussion
:Issued: 2021 May 12 1230 UTC
# Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center
Solar Activity

.24 hr Summary...
Solar activity was low. Region 2822 (Dao/Beta-Delta, N19E17 at 12/0552)
produced a C1.5 flare at 12/0935 UTC. This region showed little
significant change over the past 12 hours. Region 2823 (Cro-Beta,
S23E26 at 12/0552 UTC) remained stable. No earth-directed CMEs were
seen in SOHO/LASCO coronagraph imagery during the past 24 hours.

A chance for C-class flares will persist through the forecast period.
Region 2821 is anticipated to return on day 2 (13 May).

Energetic Particle

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

The greater than 2 MeV electron flux and the greater than 10 MeV proton
flux at geosynchronous orbit are expected to remain at background

Solar Wind

.24 hr Summary...
An IP shock arrived at the DSCOVR spacecraft at 12/0547 UTC. Solar wind
speed jumped from around 320 km/s to 450 km/s with similar jumps in
density, temperature, and magnetic field. After a short period of
southward Bz (-7nT) immediately after shock arrival, Bz was
predominantly positive. Bt reached 20 nT but had declined to around 10
nT by forecast time. Bz also reached 20nT, but it was stubbornly
positive during that roughly two hour period. This shock is most likely
the early arrival of the 9 May CME.

Disturbed solar wind conditions are expected to persist for the next 24
hours with CME passage. Nominal solar wind conditions are expected to
return for days 2 and 3 (13-14 May).


.24 hr Summary...
The geomagnetic field was quiet until 12/0643 UTC when the IP shock
arrived at earth. The arrival was marked by a 51 nT sudden impulse at
the Fredericksburg, VA ground magnetometer. By 12/0711, the geomagnetic
field activity had risen to active levels (Kp=4). Although a warning
was issued for G1 (Kp=5) conditions, the predominantly positive Bz
component inhibited minor storm conditions.

A chance for active conditions will linger into day 2 (13 May) as the
CME passes, with a lingering chance of a minor (G1) period. Day 3 (14
May) is expected to see a return to quiet to unsettled conditions.