The geomagnetic field was quiet to active on May 19. Solar wind speed at SOHO ranged between 307 and 390 km/sec. The high latitude magnetometer at Andenes recorded quiet to minor storm levels. Solar wind speed increased slowly after 18h UT at DSCOVR and a corotating interaction region associated with CH1148 caused increasing geomagnetic activity after 21h. The disturbance intensified early on May 20 when major storming was recorded.
Solar flux density measured at 20h UT on 2.8 GHz was 164.6 - increasing 23.4 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 140.73. In comparison SC24 peaked on June 28, 2014 at 145.50). The Potsdam WDC planetary A index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 6.6). Three hour interval K indices: 11111224 (planetary), ******** (Boulder), 00101445 (Andenes).
The background x-ray flux is at the class C2 level (GOES 16).
At the time of counting spots (see image time), spots were observed in 13 active regions using 2K resolution (SN: 305) and in 10 active regions using 1K resolution (SN: 188) SDO/HMI images.
Region 13302 [N17W57] decayed slowly and quietly.
Region 13305 [N11W55] produced a few low level flares and appeared to
be consolidating. A minor M class flare is possible.
Region 13308 [N11W40] still has minor polarity intermixing and
decayed in the leading spot section.
Region 13309 [S18W76] decayed slowly and was mostly quiet.
Region 13310 [S21E48] displayed only minor changes and was mostly
quiet. An M class flare is possible.
Region 13311 [N18E61] continued to be very active producing many C
and M flares. The region is complex and compact with polarity intermixing
and magnetic deltas. Major flares are possible. C1 flares: C1.8 @ 11:52 UT
New region 13312 [S24E70] rotated partly into view on May 18 and was
numbered by SWPC the next day. A few C flares were recorded. The region
appears to be in slow decay.
New region 13313 [N21E76] rotated into view with a large, mature
spot.
Spotted regions not observed (or interpreted
differently) by SWPC:
S8569 [S30E03] was quiet and stable.
New region S8573 [N14E50] emerged with several small spots.
New region S8574 [N24E08] was observed with tiny spots in an
old plage area.
New region S8575 [N35E27] emerged with tiny
spots.
New region S8576 [S22W30] was observed with tiny spots in an
old plage area.
C2+ flares:
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C5.1 | 00:15 | 13310 | GOES16 | simultaneous flare in AR 13311 | |
| M5.3/1N | 00:48 | N18E74 | 13311 | GOES16 | |
| C2.6 | 02:04 | 13312 | GOES16 | ||
| C2.9 | 02:16 | 13308 | GOES16 | ||
| C2.6 | 02:33 | 13309 | GOES16 | ||
| C6.9 | 02:58 | N19E72 | 13311 | GOES16 | |
| M1.6 | 03:12 | N19E72 | 13311 | GOES16 | |
| C2.9 | 04:45 | N19E72 | 13311 | GOES16 | |
| M2.5/1N | 05:00 | N19E72 | 13311 | GOES16 | |
| C3.9 | 05:39 | 13310 | GOES16 | simultaneous flare in AR 13311 | |
| C3.1 | 06:07 | 13311 | GOES16 | ||
| C3.2 | 06:31 | N19E72 | 13311 | GOES16 | simultaneous flare in AR 13309 |
| C5.7 | 06:49 | 13311 | GOES16 | ||
| C4.0 | 07:10 | 13311 | GOES16 | simultaneous flare in AR 13305 | |
| C4.7 | 07:42 | 13311 | GOES16 | simultaneous flare in AR 13305 | |
| C2.8 | 09:30 | N18E70 | 13311 | GOES16 | |
| C4.0 | 10:17 | N18E70 | 13311 | GOES16 | |
| C6.1 | 12:39 | N16E65 | 13311 | GOES16 | |
| C2.9 | 15:35 | 13311 | GOES16 | simultaneous flare in AR 13305 | |
| C2.6 | 15:54 | 13311 | GOES16 | ||
| C5.9 | 16:31 | 13311 | GOES16 | ||
| C4.1 | 17:21 | 13311 | GOES16 | ||
| C5.3 | 17:29 | 13311 | GOES16 | ||
| C2.0 | 18:52 | 13311 | GOES16 | ||
| C5.1 | 19:14 | 13312 | GOES16 | ||
| C3.2 | 19:43 | 13311 | GOES16 | ||
| M2.3 | 20:06 | N16E61 | 13311 | GOES16 | |
| M2.7 | 20:26 | 13311 | GOES16 | ||
| M1.5 | 21:14 | 13311 | GOES16 | ||
| C3.3 | 22:48 | 13312 | GOES16 | simultaneous flare in AR 13311 | |
| C2.1 | 23:34 | 13311 | GOES16 |
May 18-19: No obviously Earth directed CMEs were
observed.
May 17: A filament eruption associated with a C4 flare in AR 13309
was the source of a CME that may have Earth directed components. If that's
the case weak effects could reach Earth on May 20 or 21.
[Coronal hole history (since October 2002)]
[Compare today's report to the situation one solar rotation ago:
28 days ago
27 days ago
26 days ago]
A recurrent trans equatorial coronal hole (CH1148) was Earth facing on May 16-17. A southern hemisphere coronal hole (CH1149) will likely rotate across the central meridian on May 20-22.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle and high latitudes is poor. Propagation on long distance northeast-southwest paths is poor.
Quiet to major storm is expected for May 20 due to effects related to CH1148. Quiet to unsettled conditions are likely on May 21-22. A high speed stream from CH1149 could cause unsettled to major storm conditions May 23-25.
| Coronal holes (1) | Coronal mass ejection (2) | M and X class flares (3) |
1) Effects from a coronal hole
could reach Earth within the next 5 days. When the high speed
stream has arrived the color changes to green.
2) Effects from a CME are likely to be observed at Earth within 96 hours.
3) There is a possibility of either M or X class flares within the next 48 hours.
Green: 0-30% probability, Yellow: 30-70% probability, Red: 70-100% probability.
(Click on image for 2K resolution).
4K resolution.
Compare to the previous day's image. 0.5K image
When available the active region map has a coronal hole polarity overlay where red (pink) is negative and blue is positive.
Data for all officially numbered solar regions according to the Solar Region Summary provided by NOAA/SWPC, all other regions are numbered sequentially as they emerge using the STAR spot number. Comments are my own, as is the STAR spot count (spots observed at or inside a few hours before midnight) and data for regions not numbered by SWPC or where SWPC has observed no spots. SWPC active region numbers in the table below and in the active region map above are the historic SWPC/USAF numbers. SWPC data considered to be not sufficiently precise (location, area, classification) are colored red.
| Active region | SWPC date numbered STAR detected |
Spot count | Location at midnight | Area | Classification | SDO / HMI 4K continuum image with magnetic polarity overlays |
Comment | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| SWPC/ USAF |
Magnetic (SDO) |
SWPC | STAR | Current | Previous | ||||||
| 2K | 1K | ||||||||||
| 13303 | 2023.05.07 2023.05.09 |
S10W83 | location: S12W74 | ||||||||
| 13301 | 2023.05.08 2023.05.09 |
N14W65 |
 |
location: N14W62 |
|||||||
| 13304 | 2023.05.08 2023.05.11 |
N20W89 | |||||||||
| 13302 | 2023.05.08 2023.05.09 |
1 | 1 | 1 | N18W58 | 0050 | HSX | HSX |
 |
 |
area: 0080 location: N17W57 |
| 13305 | 2023.05.12 | 18 | 28 | 18 | N12W57 | 0240 | DAI | DAI |
 |
 |
location: N11W55 area: 0320 |
| S8558 | 2023.05.13 | S37W46 | |||||||||
| S8560 | 2023.05.14 | S28W54 | |||||||||
| 13308 | 2023.05.14 2023.05.16 |
15 | 32 | 18 | N12W41 | 0070 | CAO | DRI |
 |
 |
location: N11W40 area: 0120 |
| 13307 | 2023.05.14 2023.05.15 |
1 | S09W20 | 0010 | AXX |
 |
spotless location: S10W18 |
||||
| S8565 | 2023.05.14 | S21W35 | |||||||||
| S8566 | 2023.05.15 | N21W11 | |||||||||
| 13309 | 2023.05.16 2023.05.17 |
3 | 6 | 3 | S18W77 | 0010 | BXO | BXO |
 |
 |
area: 0030 location: S18W76 |
| 13310 | 2023.05.16 2023.05.17 |
8 | 14 | 7 | S20E48 | 0320 | CKO | CKO |
 |
 |
location: S21E48 area: 0580 |
| S8569 | 2023.05.16 | 4 | S30E03 | 0004 | BXO |
 |
 |
||||
| 13311 | 2023.05.17 2023.05.18 |
12 | 47 | 25 | N17E60 | 0330 | EKC | EAC |
 |
 |
beta-delta location: N18E61 area: 0550 |
| 13312 | 2023.05.18 2023.05.19 |
6 | 24 | 8 | S25E70 | 0040 | CRO | DRI |
 |
 |
area: 0100 location: S24E70 |
| 13313 | 2023.05.18 2023.05.19 |
1 | 1 | 1 | N22E75 | 0030 | HSX | HSX |
 |
was AR S8572 location: N21E76 area: 0230 |
|
| S8573 | 2023.05.19 | 7 | 5 | N14E50 | 0020 | DRO |
 |
||||
| S8574 | 2023.05.19 | 6 | N24E08 | 0008 | BXO |
 |
|||||
| S8575 | 2023.05.19 | 2 | 2 | N35E27 | 0007 | BXO |
 |
||||
| S8576 | 2023.05.19 | 3 | S22W30 | 0005 | BXO |
 |
|||||
| Total spot count: | 65 | 175 | 88 | ||||||||
| Sunspot number: | 155 | 305 | 188 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 108 | 214 | 127 | (Sum of total spot count + classification weighting for each AR. Classification weighting: X=0, R=3, A/S=5, H/K=10) | |||||||
| Relative sunspot number (Wolf number): | 171 | 168 | 150 | ||||||||
| Month | Average solar flux | International sunspot number (WDC-SILSO) |
Smoothed sunspot number (4) | Average ap (3) |
|
|---|---|---|---|---|---|
| Measured | 1 AU | ||||
| 2014.02 | 170.3 (cycle peak) |
166.3 | 146.1 (SC24 peak) | 110.5 | 10.70 |
| 2014.04 | 143.9 | 144.8 | 112.5 | 116.4 (SC24 solar max) | 7.88 |
| 2017.09 | 91.3 | 92.3 | 43.6 | 18.2 (-1.3) | 18.22 (SC24 peak) |
| 2019.11 | 70.2 | 68.7 | 0.5 | 2.0 (-0.6) (Solar minimum using 365d smoothing: November 17, 2019) |
4.19 |
| 2019.12 | 70.8 | 68.6 | 1.6 | 1.8 (-0.2) (ISN 13 months smoothed solar minimum) |
3.22 |
| 2021.09 | 87.0 | 88.2 | 51.3 | 40.2 (+4.8) | 6.33 |
| 2021.10 | 88.9 | 88.3 | 37.4 | 45.2 (+5.0) | 7.38 |
| 2021.11 | 86.2 | 84.4 | 34.8 | 50.8 (+5.6) | 9.83 |
| 2021.12 | 103.0 | 99.8 | 67.5 | 55.9 (+5.1) | 6.40 |
| 2022.01 | 103.8 | 100.5 | 55.3 | 60.1 (+4.2) | 8.92 |
| 2022.02 | 109.1 | 106.5 | 60.9 | 64.7 (+4.6) | 10.46 |
| 2022.03 | 117.0 | 115.8 | 78.6 | 68.7 (+4.0) | 10.20 |
| 2022.04 | 130.8 | 131.7 | 84.0 | 73.0 (+4.3) | 11.79 |
| 2022.05 | 133.8 | 136.8 | 96.5 | 77.4 (+4.4) | 7.48 |
| 2022.06 | 116.1 | 119.8 | 70.3 | 81.1 (+3.7) | 8.20 |
| 2022.07 | 125.4 | 129.5 | 91.4 | 86.7 (+5.6) | 9.51 |
| 2022.08 | 114.2 | 117.1 | 74.6 | 92.5 (+5.8) | 10.92 |
| 2022.09 | 135.1 | 136.5 | 96.0 | 96.4 (+3.9) | 12.18 |
| 2022.10 | 133.5 | 132.7 | 95.5 | 98.7 (+2.3) | 11.16 |
| 2022.11 | 123.4 | 120.7 | 80.5 | (100.4 projected, +1.7) | 9.33 |
| 2022.12 | 147.9 | 143.4 | 112.8 | (104.1 projected, +3.7) | 10.99 |
| 2023.01 | 182.4 | 176.6 | 143.6 | (110.1 projected, +6.0) | 8.73 |
| 2023.02 | 167.2 | 163.2 | 110.9 | (115.2 projected, +5.1) | 14.48 (current SC25 peak) |
| 2023.03 | 157.2 | 155.6 | 122.6 | (118.3 projected, +3.1) | 14.42 |
| 2023.04 | 145.4 | 146.4 | 96.4 | (123.7 projected, +5.4) | 13.40 |
| 2023.05 | 154.1 (1) | 74.3 (2A) / 121.2 (2B) / 146.9 (2C) | (129.3 projected, +5.6) | (9.9) | |
| 2023.06 | (132.5 projected, +3.2) | ||||
| 2023.07 | (132.0 projected, -0.5) | ||||
| 2023.08 | (133.0 projected, +1.0) | ||||
| 2023.09 | (136.4 projected, +3.4) | ||||
| 2023.10 | (138.3 projected, +1.9) | ||||
| 2023.11 | (141.4 projected, +3.1) | ||||
| 2023.12 | (142.5 projected max SC25) | ||||
1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz
and any corrections applied to that measurement.
2A) Current impact on the monthly sunspot number based on the Boulder (NOAA/SWPC) sunspot number (accumulated daily sunspots / month days).
2B) Boulder SN current month average to date.
2C) STAR SDO 1K Wolf number 30 day average.
3) Running average based on the quicklook and definitive Potsdam WDC ap indices. Values in red
are based on the definitive international
GFZ Potsdam WDC ap indices.
4) Source: SIDC-SILSO.
This report has been prepared by Jan Alvestad. It is based on the analysis of data from whatever sources are available at the time the report is prepared. All time references are to Universal Time. Comments and suggestions are always welcome.
SDO images are courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.
