Report of Solar Geophysical Activity (RSGA)

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast SDF Number 151 Issued at 2200Z on 31 May 2021
IA. Analysis of Solar Active Regions and Activity from 30/2100Z to 31/2100Z: Solar activity has been at very low levels for the past 24 hours. There are currently 2 numbered sunspot regions on the disk. IB. Solar Activity Forecast: Solar activity is expected to be very low with a chance for a C-class flares on days one, two, and three (01 Jun, 02 Jun, 03 Jun).
IIA. Geophysical Activity Summary 30/2100Z to 31/2100Z: The geomagnetic field has been at quiet to unsettled levels for the past 24 hours. Solar wind speed reached a peak of 423 km/s at 30/2250Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 176 pfu. IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to active levels on days one and two (01 Jun, 02 Jun) and quiet to unsettled levels on day three (03 Jun).
III. Event probabilities 01 Jun-03 Jun Class M 01/01/01 Class X 01/01/01 Proton 01/01/01 PCAF green
IV. Penticton 10.7 cm Flux Observed 31 May 082 Predicted 01 Jun-03 Jun 082/082/082 90 Day Mean 31 May 077
V. Geomagnetic A Indices Observed Afr/Ap 30 May 007/007 Estimated Afr/Ap 31 May 005/005 Predicted Afr/Ap 01 Jun-03 Jun 015/018-014/015-007/008
VI. Geomagnetic Activity Probabilities 01 Jun-03 Jun A. Middle Latitudes Active 35/35/15 Minor Storm 10/10/05 Major-severe storm 01/01/01 B. High Latitudes Active 15/15/15 Minor Storm 30/30/25 Major-severe storm 45/45/25
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Forecast Discussion

Product: Forecast Discussion Issued: 2021 May 31 1230 UTC Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center
Solar Activity
.24 hr Summary… Solar activity was very low. Region 2827 (N12E22, Dao/beta) exhibited minor growth this period while Region 2828 (S31E26, Axx/alpha) was in decay. No Earth-directed CMEs were observed in available data.
.Forecast… Solar activity is expected to be very low over 31 May-02 Jun.
Energetic Particle
.24 hr Summary… The greater than 2 MeV electron flux was normal to moderate and the greater than 10 MeV proton flux was steady at background levels.
.Forecast… The greater than 2 MeV electron flux is expected to be normal to moderate over 31 May-02 Jun and the greater than 10 MeV proton flux is expected to persist at background levels throughout the forecast period.
Solar Wind
.24 hr Summary… Solar wind parameters were indicative of a return to a nominal solar wind environment. Solar wind speeds decreased from initial values near 450 km/s to end-of-period readings between 350-400 km/s. Total field strength varied between 1-4 nT and Bz remained near 0 nT. The phi angle was variable and solar wind density decreased below 5 ppcm.
.Forecast… Ambient solar wind conditions are expected to prevail for the remainder of 31 May. Solar wind parameters are likely to become enhanced on 01-02 Jun due to the influence of a negative polarity CH HSS and the anticipated glancing-blow arrival of the 28 May CME.
Geospace
.24 hr Summary… The geomagnetic field was quiet to unsettled.
.Forecast… The geomagnetic field is expected to be mostly quiet through the remainder of 31 May. Unsettled and active conditions are likely on 01-02 Jun due to the influence of a negative polarity CH HSS and the anticipated glancing-blow arrival of the 28 May CME.
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NOAA 3-Day Forecast

Product: 3-Day Forecast Issued: 2021 May 31 1230 UTC Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center
A. NOAA Geomagnetic Activity Observation and Forecast
The greatest observed 3 hr Kp over the past 24 hours was 3 (below NOAA Scale levels). The greatest expected 3 hr Kp for May 31-Jun 02 2021 is 4 (below NOAA Scale levels).
NOAA Kp index breakdown May 31-Jun 02 2021
May 31 Jun 01 Jun 02 00-03UT 1 2 4 03-06UT 1 2 4 06-09UT 1 3 4 09-12UT 1 3 3 12-15UT 1 3 3 15-18UT 1 4 2 18-21UT 2 4 2 21-00UT 2 4 2
Rationale: No G1 (Minor) or greater geomagnetic storms are expected. No significant transient or recurrent solar wind features are forecast.
B. NOAA Solar Radiation Activity Observation and Forecast
Solar radiation, as observed by NOAA GOES-16 over the past 24 hours, was below S-scale storm level thresholds.
Solar Radiation Storm Forecast for May 31-Jun 02 2021
May 31 Jun 01 Jun 02 S1 or greater 1% 1% 1%
Rationale: No S1 (Minor) or greater solar radiation storms are expected. No significant active region activity favorable for radiation storm production is forecast.
C. NOAA Radio Blackout Activity and Forecast
No radio blackouts were observed over the past 24 hours.
Radio Blackout Forecast for May 31-Jun 02 2021
May 31 Jun 01 Jun 02 R1-R2 1% 1% 1% R3 or greater 1% 1% 1%
Rationale: No R1 (Minor) or greater radio blackouts are expected. No significant active region flare activity is forecast.
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Geoalert

:Product: GEOALERT :Issued: 2021 May 31 0330 UTC # Prepared by the U.S. Dept. of Commerce, NOAA, # Space Weather Prediction Center. # Geoalert WWA151 UGEOA 20401 10531 0330/ 9930/ 10311 20311 30311 99999 UGEOE 20401 10531 0330/ 30/00 99999 UGEOI 20401 10531 0330/ 30/// 10027 20740 3006/ 4///0 50000 61207 75304 80103 90070 99999 UGEOR 20401 10531 0330/ 30/24 31102 12827 20000 30100 43112 50060 60005 12911 01000 12828 20000 30000 41001 50010 60002 23332 00000 99999

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Preliminary Report and Forecast of Solar Geophysical Data (The Weekly)

The latest version of “The Weekly” Preliminary Report and Forecast of Solar Geophysical Data is now posted on-line and available at www.swpc.noaa.gov/products/weekly-highlights-and-27-day-forecast
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Space Weather Outlook

Official Space Weather Advisory issued by NOAA Space Weather Prediction Center Boulder, Colorado, USA
SPACE WEATHER ADVISORY OUTLOOK #21-24 2021 May 30 at 9:01 p.m. MDT (2021 May 31 0301 UTC)
**** SPACE WEATHER OUTLOOK ****
Summary For May 24-30
G1 (Minor) geomagnetic storm levels were observed on 26 May due to CME activity from 22-23 May.
S1 (Minor) solar radiation storm conditions were observed on 29 May associated with a C9/1f flare at 28/2313 UTC from Region 2824.
Outlook For May 31-June 6
There is a slight chance for G1 (Minor) geomagnetic storm levels on 01-02 Jun due to a potential glancing blow from a CME observed on 28 May.
Data used to provide space weather services are contributed by NOAA, USAF, NASA, NSF, USGS, the International Space Environment Services and other observatories, universities, and institutions. More information is available at SWPC’s Web site swpc.noaa.gov
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Solar & Geophysical Activity Summary (SGAS)

:Product: Solar and Geophysical Activity Summary :Issued: 2021 May 31 0245 UTC # Prepared jointly by the U.S. Dept. of Commerce, NOAA, # Space Weather Prediction Center and the U.S. Air Force. # Joint USAF/NOAA Solar and Geophysical Activity Summary SGAS Number 151 Issued at 0245Z on 31 May 2021 This report is compiled from data received at SWO on 30 May A. Energetic Events Begin Max End Rgn Loc Xray Op 245MHz 10cm Sweep None B. Proton Events: None. C. Geomagnetic Activity Summary: The geomagnetic field was quiet to unsettled. D. Stratwarm: Not Available E. Daily Indices: (real-time preliminary/estimated values) 10 cm 074 SSN 027 Afr/Ap 007/007 X-ray Background B1.2 Daily Proton Fluence (flux accumulation over 24 hrs) GT 1 MeV 7.8e+06 GT 10 MeV 5.3e+04 p/(cm2-ster-day) (GOES-16 satellite synchronous orbit W75 degrees) Daily Electron Fluence GT 2 MeV 2.10e+06 e/(cm2-ster-day) (GOES-16 satellite synchronous orbit W75 degrees) 3 Hour K-indices: Boulder 2 1 1 2 2 2 2 3 Planetary 1 1 1 1 1 2 2 3 F. Comments: None.
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NOAA 3-Day Forecast

Product: 3-Day Forecast Issued: 2021 May 31 0030 UTC Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center
A. NOAA Geomagnetic Activity Observation and Forecast
The greatest observed 3 hr Kp over the past 24 hours was 3 (below NOAA Scale levels). The greatest expected 3 hr Kp for May 31-Jun 02 2021 is 4 (below NOAA Scale levels).
NOAA Kp index breakdown May 31-Jun 02 2021
May 31 Jun 01 Jun 02 00-03UT 2 2 4 03-06UT 1 2 4 06-09UT 1 3 4 09-12UT 1 3 3 12-15UT 1 3 3 15-18UT 1 4 2 18-21UT 2 4 2 21-00UT 2 4 2
Rationale: No G1 (Minor) or greater geomagnetic storms are expected. Unsettled to active levels are expected on 01-02 Jun due to a potential glancing blow from the 28 May CME.
B. NOAA Solar Radiation Activity Observation and Forecast
Solar radiation, as observed by NOAA GOES-16 over the past 24 hours, was below S-scale storm level thresholds.
Solar Radiation Storm Forecast for May 31-Jun 02 2021
May 31 Jun 01 Jun 02 S1 or greater 1% 1% 1%
Rationale: No S1 (Minor) or greater solar radiation storms are expected. No significant active region activity favorable for radiation storm production is forecast.
C. NOAA Radio Blackout Activity and Forecast
No radio blackouts were observed over the past 24 hours.
Radio Blackout Forecast for May 31-Jun 02 2021
May 31 Jun 01 Jun 02 R1-R2 1% 1% 1% R3 or greater 1% 1% 1%
Rationale: No R1 (Minor) or greater radio blackouts are expected. No significant active region flare activity is forecast.
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Forecast Discussion

Product: Forecast Discussion Issued: 2021 May 31 0030 UTC Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center
Solar Activity
.24 hr Summary… Solar activity was very low. Region 2824 (N18, L=193) transited the west limb. Region 2827 (N11E29, Cro/beta) exhibited growth in area and spot count and produced some B-class activity. New Region 2828 (S32E33, Axx/alpha) was quiet and stable. No Earth-directed CMEs were observed in available satellite imagery.
.Forecast… Solar activity is expected to be very low over 31 May-02 Jun.
Energetic Particle
.24 hr Summary… The greater than 10 MeV proton flux returned to background levels. The greater than 2 MeV electron flux was at normal to moderate levels.
.Forecast… The greater than 10 MeV proton flux is expected to persist at background levels over 31 May-02 Jun. The greater than 2 MeV electron flux is expected to be at normal to moderate levels throughout the forecast period.
Solar Wind
.24 hr Summary… Solar wind parameters were slightly enhanced this period due to likely effects associated with a SSBC. Solar wind speeds remained elevated above 450 km/s with a peak of 491 km/s observed at 30/0838 UTC. After about 30/1845 UTC, wind speeds decreased to about 380 km/s. Total field strength ranged between 1-5 nT and the Bz component was between +4/-3 nT. Solar wind density was generally steady between 5-10 ppcm. Phi was variable early in the period before orienting to a mostly positive sector after about 30/0800 UTC.
.Forecast… Solar wind parameters are expected to be at mostly ambient levels on 31 May. On 01-02 Jun, the solar wind environment is likely to become enhanced due to a combination of negative polarity CH HSS influence and the anticipated glancing-blow arrival of the 28 May CME.
Geospace
.24 hr Summary… The geomagnetic field was quiet to unsettled.
.Forecast… The geomagnetic field is expected to be at mostly quiet levels on 31 May. Unsettled to active field conditions, with a slight chance for G1 (Minor) storm conditions, are likely on 01 Jun due to negative polarity CH HSS influence coupled with the anticipated glancing-blow arrival of the 28 May CME. Unsettled to active conditions are likely to continue on 02 Jun due to lingering CME effects.
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Solar Region Summary (SRS)

:Product: Solar Region Summary :Issued: 2021 May 31 0030 UTC # Prepared jointly by the U.S. Dept. of Commerce, NOAA, # Space Weather Prediction Center and the U.S. Air Force. # Joint USAF/NOAA Solar Region Summary SRS Number 151 Issued at 0030Z on 31 May 2021 Report compiled from data received at SWO on 30 May I. Regions with Sunspots. Locations Valid at 30/2400Z Nmbr Location Lo Area Z LL NN Mag Type 2827 N11E29 073 0060 Cro 05 05 Beta 2828 S32E33 069 0010 Axx 01 02 Alpha IA. H-alpha Plages without Spots. Locations Valid at 30/2400Z May Nmbr Location Lo 2825 N17W45 147 II. Regions Due to Return 31 May to 02 Jun Nmbr Lat Lo 2822 N17 353
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