XPost: rec.radio.amateur.dx, rec.radio.shortwave, rec.radio.info

:Product: Weekly Highlights and Forecasts
:Issued: 2024 May 06 0628 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
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# Weekly Highlights and Forecasts
#
Highlights of Solar and Geomagnetic Activity
29 April - 05 May 2024

Solar activity was at moderate to high levels. Moderate levels were
observed on 29 Apr and 01-02 May. High levels were reached on 30
Apr, due in part to an M9.5/2b flare at 30/2346 UTC from Region 3654
(S07, L=134, class/area Fkc/550 on 30 Apr). Region 3654 was the
largest and most complex spot group on 28 Apr-01 May, however it was
in decay as it approached the SW limb on 01 May. The region produced
a total of 11 M-class flares. On 30 Apr, Region 3663 (N26, L=037,
class/area Fkc/580 on 05 May) emerged in the NE quadrant, followed
by Region 3664 (S19, L=352, class/area Ekc/580 on 05 May) on 01 May.
Both regions grew steadily over the following days. Region 3663
produced 17 M-class flares and 3 X-class flares while Region 3664
produced only 5 M-class flares. The three X-class flares included an
X1.6/1b at 03/0222 UTC, an X1.3/1b at 05/0601 UTC, and an X1.2/1b at
05/1154 UTC. The X1.6 flare had associated Type II (959 km/s) and IV
radio sweeps, a 550 sfu Tenflare and an associated CME first
observed in SOHO/LASCO C2 imagery at 03/0248 UTC. Modelling of the
event showed a potential glancing blow arriving around 05/1800 UTC.
There were two further CME runs of note. Those included an eruption
near N13W09 at 29/0909 UTC that displayed a westward flow across
GOES 16 SUVI imagery. C2 imagery showed a CME off the NW limb at
29/1248 UTC that was modelled as a potential glancing blow on 03 May
around 1500 UTC. Lastly, a CME that was associated with a C3.9 flare
at 03/2037 UTC from a plage area in the NE quadrant. The flare had
associated Type II (392 km/s) and Type IV radio emissions and a CME
first observed in C3 imagery at 03/2218 UTC. Analysis showed a
potential glancing blow on 09 May. Other eruptive events associated
with radio signatures were observed, but did not produce ejecta
determined to be on the Sun-Earth line.

No proton events were observed at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit was at
normal to moderate levels throughout.

Solar wind parameters began the period under mild positive polarity
CH HSS influence solar wind speed was mostly in the 450-500 km/s
range and total field around 2-4 nT. Solar wind speed began to
diminish to nominal levels on 30 Apr. After 30/1130 UTC, the first
of three CMEs were observed. Total field increased to near 14 nT
while the Bz component rotated from -9 nT to +13 nT. Solar wind
speed continued to decrease to near 350 km/s. The geomagnetic field
responded with quiet levels on 29 Apr, followed by quiet to active
levels on 30 Apr-01 May. On 02 May, a shock arrival was observed at
02/1317 UTC, indicating the arrival of the second CME. This CME was
possibly the one that left the Sun on 29 Apr. The IMF increased to approximately 21 nT and the Bz component shifted southward to -19
nT. Solar wind speed increased initially to near 450 km/s and later
to near 510 km/s on 03 May. The geomagnetic field responded with
unsettled to G3 (Strong) storm levels on 02 May and quiet to active
levels on 03 May. By early on 03 May, the IMF had decreased to
nominal levels with solar wind speed slowly returning to background
conditions. Nominal conditions returned on 04 May and through the
midday on 05 May. Around 05/1500 UTC, another enhancement was
observed in the IMF, likely the arrival of the 03 May CME. Total
field strength increased gradually to 14 nT while the Bz component
reached a southward deflection of -12 nT. Solar wind speed increased
to near 380 km/s. The geomagnetic field responded with unsettled to
active levels late on 05 May.

Forecast of Solar and Geomagnetic Activity
06 May - 01 June 2024

Solar activity is expected to be at moderate to high levels (R1-R3/Minor-Strong) through 12 May as Regions 3663 and 3664 rotate
across the visible disk. Low to moderate levels are expected on 12
May-01 Jun.

There is a chance for S1-S2 (Minor-Moderate) solar radiation storm
levels on 06-13 May due to the flare potential of Regions 3663 and
3664.

The greater than 2 MeV electron flux at geosynchronous orbit is
expected to be at normal to moderate levels on 06 May-01 Jun.

Geomagnetic field activity is expected to be at unsettled to G2
(Moderate) storm levels on 06 May due to persistent CME influence.
The geomagnetic field is expected to reach unsettled to active
levels on 07-09 May, 12-14 May, 23-25 May, 27-28 May, and 31 May-01
Jun due to recurrent CH HSS activity.

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