864
FXXX12 KWNP 110031
DAYDIS

:Product: Forecast Discussion
:Issued: 2024 May 11 0030 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 was high. Region 3664 (S17W48, Fkc/beta-gamma-delta)
produced the vast majority of X-ray flare activity this period; the
largest of which was an X3.9/2b flare at 10/0654 UTC. Strong radio
bursts and Type II and IV radio sweeps were associated with the X3.9,
and the associated halo CME is expected to arrive on 12 May. Region 3664
continued a trend of growth and was quite dynamic throughout the period,
especially in the intermediate spot area. The remaining regions were
either stable or in decay.

.Forecast...
Solar activity is expected to persist at high to very high levels over
11-13 May, with M-class (R1-R2/Minor-Moderate) and X-class flares
(R3/Strong) expected, due primarily to the flare potential of Region
3664.

Energetic Particle

.24 hr Summary...
The greater than 10 MeV proton flux reached S2 (Moderate) solar
radiation storm levels following strong flaring from Region 3664. The 10
MeV proton flux reached S1 (Minor) levels beginning at 10/1335 UTC, and
reached S2 (Moderate) levels beginning at 10/1745 UTC with a peak flux
of 207 pfu observed at 10/1745 UTC. The greater than 2 MeV electron flux
was at normal to moderate levels throughout the day.

.Forecast...
The greater than 10 MeV proton flux is expected to persist at S1 (Minor)
storm levels through the first half of 11 May. An additional proton
enhancement at S1 levels is likely on 12-13 May due to the flare
potential and location of Region 3664. The greater than 2 MeV electron
flux is expected to be at normal to moderate levels over 11-13 May.

Solar Wind

.24 hr Summary...
This period saw the arrival of an strong interplanetary shock beginning
at around 10/1635 UTC. Following initial shock arrival, total field
strength increased to a peak of 55 nT and Bz was sustained southward, by
as much as -47 nT, after 10/1645 UTC. Solar wind speeds increased
sharply to around 700 km/s following shock arrival, with a peak value of
741 km/s observed at 10/1735 UTC. Conditions further enhanced later in
the period, seeing Bt reach 74 nT, Bz deviate southward to near -50 nT,
and solar winds peak over 800 km/s.

.Forecast...
A strongly enhanced solar wind environment and CME influences are
expected to continue on 11 May. A weaker enhancement is likely on 12-13
May due to CH HSS influences and the anticipated arrival of at least two
halo CMEs that left the Sun over 09-10 May.

Geospace

.24 hr Summary...
The geomagnetic field rapidly increased from unsettled levels to G4, and
eventually G5 (Severe) geomagnetic storm levels this period following
the arrival of a CME. The CME arrived in solar wind data beginning at
around 10/1635 UTC, and arrived at Earth at around 10/1656 UTC with a
108 nT deviation measured at the Boulder magnetometer.

.Forecast...
Periods of G3-G5 (Strong-Severe) geomagnetic storms are expected on 11
May due to continued CME activity. Periods of G1-G2 (Minor-Moderate)
storming are likely on 12 May due to the anticipated arrival of at least
two more halo CMEs associated with activity from Region 3664 on 09-10
May, in addition to the onset of CH HSS influences. Unsettled and active
conditions are expected on 12 May due to waning CME influences and
continued CH HSS influences.