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Update
WATCH
Geomagnetic Storm Category G1 Predicted
Issued: 16.05.2021 12.37 am UTC
Geomagnetic Storm Category G1 Predicted

Highest Storm Level Predicted by Day:
May 17: None (Below G1) May 18: G1 (Minor) May 19: None (Below G1)

THIS SUPERSEDES ANY/ALL PRIOR WATCHES IN EFFECT

Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

EXTENDED WARNING
Geomagnetic K-index of 4 expected
Issued: 13.05.2021 05.31 am UTC
Geomagnetic K-index of 4 expected
Extension to Serial Number: 3898
Valid From: 2021 May 12 0600 UTC
Now Valid Until: 2021 May 13 1500 UTC
Warning Condition: Persistence

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

EXTENDED WARNING
Geomagnetic K-index of 4 expected
Issued: 12.05.2021 05.59 pm UTC
Geomagnetic K-index of 4 expected
Extension to Serial Number: 3897
Valid From: 2021 May 12 0600 UTC
Now Valid Until: 2021 May 13 0600 UTC
Warning Condition: Persistence

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

EXTENDED WARNING
Geomagnetic K-index of 5 expected
Issued: 12.05.2021 05.59 pm UTC
Geomagnetic K-index of 5 expected
Extension to Serial Number: 1600
Valid From: 2021 May 12 0700 UTC
Now Valid Until: 2021 May 13 0600 UTC
Warning Condition: Persistence

Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

EXTENDED WARNING
Geomagnetic K-Index of 6 expected
Issued: 12.05.2021 05.59 pm UTC
Geomagnetic K-Index of 6 expected
Extension to Serial Number: 443
Valid From: 2021 May 12 1225 UTC
Now Valid Until: 2021 May 12 2359 UTC
Warning Condition: Persistence

Potential Impacts: Area of impact primarily poleward of 55 degrees Geomagnetic Latitude.
Induced Currents - Power grid fluctuations can occur. High-latitude power systems may experience voltage alarms.
Spacecraft - Satellite orientation irregularities may occur; increased drag on low Earth-orbit satellites is possible.
Radio - HF (high frequency) radio propagation can fade at higher latitudes.
Aurora - Aurora may be seen as low as New York to Wisconsin to Washington state.

EXTENDED WARNING
Geomagnetic K-index of 7 or greater expected
Issued: 12.05.2021 05.59 pm UTC
Geomagnetic K-index of 7 or greater expected
Extension to Serial Number: 77
Valid From: 2021 May 12 1250 UTC
Now Valid Until: 2021 May 12 2359 UTC
Warning Condition: Persistence

Potential Impacts: Area of impact primarily poleward of 50 degrees Geomagnetic Latitude.
Induced Currents - Power system voltage irregularities possible, false alarms may be triggered on some protection devices.
Spacecraft - Systems may experience surface charging; increased drag on low Earth-orbit satellites and orientation problems may occur.
Navigation - Intermittent satellite navigation (GPS) problems, including loss-of-lock and increased range error may occur.
Radio - HF (high frequency) radio may be intermittent.
Aurora - Aurora may be seen as low as Pennsylvania to Iowa to Oregon.

ALERT
Geomagnetic K-index of 7
Issued: 12.05.2021 05.59 pm UTC
Geomagnetic K-index of 7
Threshold Reached: 2021 May 12 1759 UTC
Synoptic Period: 1500-1800 UTC

Active Warning: Yes
NOAA Scale: G3 - Strong

Potential Impacts: Area of impact primarily poleward of 50 degrees Geomagnetic Latitude.
Induced Currents - Power system voltage irregularities possible, false alarms may be triggered on some protection devices.
Spacecraft - Systems may experience surface charging; increased drag on low Earth-orbit satellites and orientation problems may occur.
Navigation - Intermittent satellite navigation (GPS) problems, including loss-of-lock and increased range error may occur.
Radio - HF (high frequency) radio may be intermittent.
Aurora - Aurora may be seen as low as Pennsylvania to Iowa to Oregon.

ALERT
Geomagnetic K-index of 6
Issued: 12.05.2021 03.42 pm UTC
Geomagnetic K-index of 6
Threshold Reached: 2021 May 12 1542 UTC
Synoptic Period: 1500-1800 UTC

Active Warning: Yes
NOAA Scale: G2 - Moderate

Potential Impacts: Area of impact primarily poleward of 55 degrees Geomagnetic Latitude.
Induced Currents - Power grid fluctuations can occur. High-latitude power systems may experience voltage alarms.
Spacecraft - Satellite orientation irregularities may occur; increased drag on low Earth-orbit satellites is possible.
Radio - HF (high frequency) radio propagation can fade at higher latitudes.
Aurora - Aurora may be seen as low as New York to Wisconsin to Washington state.

ALERT
Geomagnetic K-index of 5
Issued: 12.05.2021 03.29 pm UTC
Geomagnetic K-index of 5
Threshold Reached: 2021 May 12 1528 UTC
Synoptic Period: 1500-1800 UTC

Active Warning: Yes
NOAA Scale: G1 - Minor

Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

ALERT
Geomagnetic K-index of 7
Issued: 12.05.2021 12.59 pm UTC
Geomagnetic K-index of 7
Threshold Reached: 2021 May 12 1258 UTC
Synoptic Period: 1200-1500 UTC

Active Warning: Yes
NOAA Scale: G3 - Strong

Potential Impacts: Area of impact primarily poleward of 50 degrees Geomagnetic Latitude.
Induced Currents - Power system voltage irregularities possible, false alarms may be triggered on some protection devices.
Spacecraft - Systems may experience surface charging; increased drag on low Earth-orbit satellites and orientation problems may occur.
Navigation - Intermittent satellite navigation (GPS) problems, including loss-of-lock and increased range error may occur.
Radio - HF (high frequency) radio may be intermittent.
Aurora - Aurora may be seen as low as Pennsylvania to Iowa to Oregon.

EXTENDED WARNING
Geomagnetic K-index of 5 expected
Issued: 12.05.2021 12.52 pm UTC
Geomagnetic K-index of 5 expected
Extension to Serial Number: 1599
Valid From: 2021 May 12 0700 UTC
Now Valid Until: 2021 May 12 1800 UTC
Warning Condition: Persistence

Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

WARNING
Geomagnetic K-index of 7 or greater expected
Issued: 12.05.2021 12.49 pm UTC
Geomagnetic K-index of 7 or greater expected
Valid From: 2021 May 12 1250 UTC
Valid To: 2021 May 12 1800 UTC
Warning Condition: Onset
NOAA Scale: G3 or greater - Strong to Extreme

Potential Impacts: Area of impact primarily poleward of 50 degrees Geomagnetic Latitude.
Induced Currents - Power system voltage irregularities possible, false alarms may be triggered on some protection devices.
Spacecraft - Systems may experience surface charging; increased drag on low Earth-orbit satellites and orientation problems may occur.
Navigation - Intermittent satellite navigation (GPS) problems, including loss-of-lock and increased range error may occur.
Radio - HF (high frequency) radio may be intermittent.
Aurora - Aurora may be seen as low as Pennsylvania to Iowa to Oregon.

ALERT
Geomagnetic K-index of 6
Issued: 12.05.2021 12.32 pm UTC
Geomagnetic K-index of 6
Threshold Reached: 2021 May 12 1232 UTC
Synoptic Period: 1200-1500 UTC

Active Warning: Yes
NOAA Scale: G2 - Moderate

Potential Impacts: Area of impact primarily poleward of 55 degrees Geomagnetic Latitude.
Induced Currents - Power grid fluctuations can occur. High-latitude power systems may experience voltage alarms.
Spacecraft - Satellite orientation irregularities may occur; increased drag on low Earth-orbit satellites is possible.
Radio - HF (high frequency) radio propagation can fade at higher latitudes.
Aurora - Aurora may be seen as low as New York to Wisconsin to Washington state.

ALERT
Geomagnetic K-index of 5
Issued: 12.05.2021 12.30 pm UTC
Geomagnetic K-index of 5
Threshold Reached: 2021 May 12 1230 UTC
Synoptic Period: 1200-1500 UTC

Active Warning: Yes
NOAA Scale: G1 - Minor

Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

WARNING
Geomagnetic K-Index of 6 expected
Issued: 12.05.2021 12.28 pm UTC
Geomagnetic K-Index of 6 expected
Valid From: 2021 May 12 1225 UTC
Valid To: 2021 May 12 1800 UTC
Warning Condition: Onset
NOAA Scale: G2 - Moderate

Potential Impacts: Area of impact primarily poleward of 55 degrees Geomagnetic Latitude.
Induced Currents - Power grid fluctuations can occur. High-latitude power systems may experience voltage alarms.
Spacecraft - Satellite orientation irregularities may occur; increased drag on low Earth-orbit satellites is possible.
Radio - HF (high frequency) radio propagation can fade at higher latitudes.
Aurora - Aurora may be seen as low as New York to Wisconsin to Washington state.

EXTENDED WARNING
Geomagnetic K-index of 4 expected
Issued: 12.05.2021 11.23 am UTC
Geomagnetic K-index of 4 expected
Extension to Serial Number: 3896
Valid From: 2021 May 12 0600 UTC
Now Valid Until: 2021 May 12 1800 UTC
Warning Condition: Persistence

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

ALERT
Geomagnetic K-index of 4
Issued: 12.05.2021 07.11 am UTC
Geomagnetic K-index of 4
Threshold Reached: 2021 May 12 0711 UTC
Synoptic Period: 0600-0900 UTC

Active Warning: Yes

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

SUMMARY
Geomagnetic Sudden Impulse
Issued: 12.05.2021 06.54 am UTC
Geomagnetic Sudden Impulse
Observed: 2021 May 12 0643 UTC
Deviation: 51 nT
Station: FRD

WARNING
Geomagnetic K-index of 5 expected
Issued: 12.05.2021 06.46 am UTC
Geomagnetic K-index of 5 expected
Valid From: 2021 May 12 0700 UTC
Valid To: 2021 May 12 1300 UTC
Warning Condition: Onset
NOAA Scale: G1 - Minor

Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

WARNING
Geomagnetic K-index of 4 expected
Issued: 12.05.2021 05.58 am UTC
Geomagnetic K-index of 4 expected
Valid From: 2021 May 12 0600 UTC
Valid To: 2021 May 12 1230 UTC
Warning Condition: Onset

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

WARNING
Geomagnetic Sudden Impulse expected
Issued: 12.05.2021 05.56 am UTC
Geomagnetic Sudden Impulse expected
Valid From: 2021 May 12 0554 UTC
Valid To: 2021 May 12 0700 UTC
IP Shock Passage Observed: 2021 May 12 0547 UTC

ALERT
Type II Radio Emission
Issued: 09.05.2021 03.02 pm UTC
Type II Radio Emission
Begin Time: 2021 May 09 1431 UTC
Estimated Velocity: 407 km/s

Description: Type II emissions occur in association with eruptions on the sun and typically indicate a coronal mass ejection is associated with a flare event.

SUMMARY
10cm Radio Burst
Issued: 09.05.2021 02.16 pm UTC
10cm Radio Burst
Begin Time: 2021 May 09 1354 UTC
Maximum Time: 2021 May 09 1354 UTC
End Time: 2021 May 09 1355 UTC
Duration: 1 minutes
Peak Flux: 130 sfu
Latest Penticton Noon Flux: 76 sfu

Description: A 10cm radio burst indicates that the electromagnetic burst associated with a solar flare at the 10cm wavelength was double or greater than the initial 10cm radio background. This can be indicative of significant radio noise in association with a solar flare. This noise is generally short-lived but can cause interference for sensitive receivers including radar, GPS, and satellite communications.

ALERT
Type IV Radio Emission
Issued: 07.05.2021 07.27 pm UTC
Type IV Radio Emission
Begin Time: 2021 May 07 1907 UTC

Description: Type IV emissions occur in association with major eruptions on the sun and are typically associated with strong coronal mass ejections and solar radiation storms.

ALERT
Type II Radio Emission
Issued: 07.05.2021 07.26 pm UTC
Type II Radio Emission
Begin Time: 2021 May 07 1902 UTC
Estimated Velocity: 848 km/s

Description: Type II emissions occur in association with eruptions on the sun and typically indicate a coronal mass ejection is associated with a flare event.

SUMMARY
10cm Radio Burst
Issued: 07.05.2021 07.25 pm UTC
10cm Radio Burst
Begin Time: 2021 May 07 1850 UTC
Maximum Time: 2021 May 07 1902 UTC
End Time: 2021 May 07 1915 UTC
Duration: 25 minutes
Peak Flux: 130 sfu
Latest Penticton Noon Flux: 71 sfu

Description: A 10cm radio burst indicates that the electromagnetic burst associated with a solar flare at the 10cm wavelength was double or greater than the initial 10cm radio background. This can be indicative of significant radio noise in association with a solar flare. This noise is generally short-lived but can cause interference for sensitive receivers including radar, GPS, and satellite communications.

ALERT
Type II Radio Emission
Issued: 02.05.2021 02.17 pm UTC
Type II Radio Emission
Begin Time: 2021 May 02 1129 UTC
Estimated Velocity: 523 km/s

Description: Type II emissions occur in association with eruptions on the sun and typically indicate a coronal mass ejection is associated with a flare event.

WARNING
Geomagnetic K-index of 4 expected
Issued: 02.05.2021 02.46 am UTC
Geomagnetic K-index of 4 expected
Valid From: 2021 May 02 0245 UTC
Valid To: 2021 May 02 1200 UTC
Warning Condition: Onset

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

ALERT
Electron 2MeV Integral Flux exceeded 1000pfu
Issued: 30.04.2021 04.03 pm UTC
Electron 2MeV Integral Flux exceeded 1000pfu
Threshold Reached: 2021 Apr 30 1530 UTC
Station: GOES16


Potential Impacts: Satellite systems may experience significant charging resulting in increased risk to satellite systems.

EXTENDED WARNING
Geomagnetic K-index of 4 expected
Issued: 27.04.2021 05.23 am UTC
Geomagnetic K-index of 4 expected
Extension to Serial Number: 3893
Valid From: 2021 Apr 27 0120 UTC
Now Valid Until: 2021 Apr 27 1200 UTC
Warning Condition: Onset

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

WARNING
Geomagnetic K-index of 4 expected
Issued: 27.04.2021 01.20 am UTC
Geomagnetic K-index of 4 expected
Valid From: 2021 Apr 27 0120 UTC
Valid To: 2021 Apr 27 0600 UTC
Warning Condition: Onset

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

ALERT
Geomagnetic K-index of 5
Issued: 26.04.2021 05.26 am UTC
Geomagnetic K-index of 5
Threshold Reached: 2021 Apr 26 0526 UTC
Synoptic Period: 0300-0600 UTC

Active Warning: Yes
NOAA Scale: G1 - Minor

Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

WARNING
Geomagnetic K-index of 5 expected
Issued: 26.04.2021 04.41 am UTC
Geomagnetic K-index of 5 expected
Valid From: 2021 Apr 26 0441 UTC
Valid To: 2021 Apr 26 1200 UTC
Warning Condition: Onset
NOAA Scale: G1 - Minor

Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

ALERT
Geomagnetic K-index of 4
Issued: 26.04.2021 12.54 am UTC
Geomagnetic K-index of 4
Threshold Reached: 2021 Apr 25 0054 UTC
Synoptic Period: 0000-0300 UTC

Active Warning: Yes

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

WARNING
Geomagnetic K-index of 4 expected
Issued: 26.04.2021 12.50 am UTC
Geomagnetic K-index of 4 expected
Valid From: 2021 Apr 26 0050 UTC
Valid To: 2021 Apr 26 1200 UTC
Warning Condition: Onset

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

EXTENDED WARNING
Geomagnetic K-index of 4 expected
Issued: 25.04.2021 11.56 am UTC
Geomagnetic K-index of 4 expected
Extension to Serial Number: 3890
Valid From: 2021 Apr 24 2300 UTC
Now Valid Until: 2021 Apr 25 1800 UTC
Warning Condition: persistence

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

WARNING
Geomagnetic K-Index of 6 expected
Issued: 25.04.2021 01.16 am UTC
Geomagnetic K-Index of 6 expected
Valid From: 2021 Apr 25 0115 UTC
Valid To: 2021 Apr 25 0900 UTC
Warning Condition: Onset
NOAA Scale: G2 - Moderate

Potential Impacts: Area of impact primarily poleward of 55 degrees Geomagnetic Latitude.
Induced Currents - Power grid fluctuations can occur. High-latitude power systems may experience voltage alarms.
Spacecraft - Satellite orientation irregularities may occur; increased drag on low Earth-orbit satellites is possible.
Radio - HF (high frequency) radio propagation can fade at higher latitudes.
Aurora - Aurora may be seen as low as New York to Wisconsin to Washington state.

ALERT
Geomagnetic K-index of 5
Issued: 25.04.2021 12.59 am UTC
Geomagnetic K-index of 5
Threshold Reached: 2021 Apr 25 0059 UTC
Synoptic Period: 0000-0300 UTC

Active Warning: Yes
NOAA Scale: G1 - Minor

Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

WARNING
Geomagnetic K-index of 5 expected
Issued: 25.04.2021 12.39 am UTC
Geomagnetic K-index of 5 expected
Valid From: 2021 Apr 25 0039 UTC
Valid To: 2021 Apr 25 0900 UTC
Warning Condition: Onset
NOAA Scale: G1 - Minor

Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

ALERT
Geomagnetic K-index of 4
Issued: 25.04.2021 12.30 am UTC
Geomagnetic K-index of 4
Threshold Reached: 2021 Apr 25 0027 UTC
Synoptic Period: 0000-0300 UTC

Active Warning: Yes

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

SUMMARY
Geomagnetic Sudden Impulse
Issued: 24.04.2021 11.21 pm UTC
Geomagnetic Sudden Impulse
Observed: 2021 Apr 24 2307 UTC
Deviation: 41 nT
Station: MEA

WARNING
Geomagnetic K-index of 4 expected
Issued: 24.04.2021 10.46 pm UTC
Geomagnetic K-index of 4 expected
Valid From: 2021 Apr 24 2300 UTC
Valid To: 2021 Apr 25 1200 UTC
Warning Condition: Onset

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

WARNING
Geomagnetic Sudden Impulse expected
Issued: 24.04.2021 10.44 pm UTC
Geomagnetic Sudden Impulse expected
Valid From: 2021 Apr 24 2300 UTC
Valid To: 2021 Apr 24 2330 UTC
IP Shock Passage Observed: 2021 Apr 24 2221 UTC

CONTINUED ALERT
Electron 2MeV Integral Flux exceeded 1000pfu
Issued: 24.04.2021 05.02 am UTC
Electron 2MeV Integral Flux exceeded 1000pfu
Continuation of Serial Number: 3137
Begin Time: 2021 Apr 17 1715 UTC
Yesterday Maximum 2MeV Flux: 19294 pfu

Potential Impacts: Satellite systems may experience significant charging resulting in increased risk to satellite systems.

ALERT
Geomagnetic K-index of 5
Issued: 23.04.2021 11.54 pm UTC
Geomagnetic K-index of 5
Threshold Reached: 2021 Apr 23 2354 UTC
Synoptic Period: 2100-2400 UTC

Active Warning: Yes
NOAA Scale: G1 - Minor

Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

WARNING
Geomagnetic K-index of 5 expected
Issued: 23.04.2021 11.27 pm UTC
Geomagnetic K-index of 5 expected
Valid From: 2021 Apr 23 2330 UTC
Valid To: 2021 Apr 23 2359 UTC
Warning Condition: Onset
NOAA Scale: G1 - Minor

Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

ALERT
Geomagnetic K-index of 4
Issued: 23.04.2021 10.17 pm UTC
Geomagnetic K-index of 4
Threshold Reached: 2021 Apr 23 2217 UTC
Synoptic Period: 2100-2400 UTC

Active Warning: Yes

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

WARNING
Geomagnetic K-index of 4 expected
Issued: 23.04.2021 10.04 pm UTC
Geomagnetic K-index of 4 expected
Valid From: 2021 Apr 23 2205 UTC
Valid To: 2021 Apr 24 0900 UTC
Warning Condition: Onset

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

CONTINUED ALERT
Electron 2MeV Integral Flux exceeded 1000pfu
Issued: 23.04.2021 04.59 am UTC
Electron 2MeV Integral Flux exceeded 1000pfu
Continuation of Serial Number: 3136
Begin Time: 2021 Apr 17 1715 UTC
Yesterday Maximum 2MeV Flux: 15548 pfu

Potential Impacts: Satellite systems may experience significant charging resulting in increased risk to satellite systems.

WARNING
Geomagnetic K-index of 4 expected
Issued: 23.04.2021 01.39 am UTC
Geomagnetic K-index of 4 expected
Valid From: 2021 Apr 23 0139 UTC
Valid To: 2021 Apr 23 0600 UTC
Warning Condition: Onset

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

WATCH
Geomagnetic Storm Category G2 Predicted
Issued: 22.04.2021 06.49 pm UTC
Geomagnetic Storm Category G2 Predicted

Highest Storm Level Predicted by Day:
Apr 23: None (Below G1) Apr 24: None (Below G1) Apr 25: G2 (Moderate)

THIS SUPERSEDES ANY/ALL PRIOR WATCHES IN EFFECT

Potential Impacts: Area of impact primarily poleward of 55 degrees Geomagnetic Latitude.
Induced Currents - Power grid fluctuations can occur. High-latitude power systems may experience voltage alarms.
Spacecraft - Satellite orientation irregularities may occur; increased drag on low Earth-orbit satellites is possible.
Radio - HF (high frequency) radio propagation can fade at higher latitudes.
Aurora - Aurora may be seen as low as New York to Wisconsin to Washington state.

ALERT
Type IV Radio Emission
Issued: 22.04.2021 05.52 am UTC
Type IV Radio Emission
Begin Time: 2021 Apr 22 0438 UTC

Description: Type IV emissions occur in association with major eruptions on the sun and are typically associated with strong coronal mass ejections and solar radiation storms.

ALERT
Type II Radio Emission
Issued: 22.04.2021 05.50 am UTC
Type II Radio Emission
Begin Time: 2021 Apr 22 0430 UTC
Estimated Velocity: 763 km/s

Description: Type II emissions occur in association with eruptions on the sun and typically indicate a coronal mass ejection is associated with a flare event.

CONTINUED ALERT
Electron 2MeV Integral Flux exceeded 1000pfu
Issued: 22.04.2021 05.01 am UTC
Electron 2MeV Integral Flux exceeded 1000pfu
Continuation of Serial Number: 3135
Begin Time: 2021 Apr 17 1715 UTC
Yesterday Maximum 2MeV Flux: 12720 pfu

Potential Impacts: Satellite systems may experience significant charging resulting in increased risk to satellite systems.

CONTINUED ALERT
Electron 2MeV Integral Flux exceeded 1000pfu
Issued: 21.04.2021 04.59 am UTC
Electron 2MeV Integral Flux exceeded 1000pfu
Continuation of Serial Number: 3134
Begin Time: 2021 Apr 17 1715 UTC
Yesterday Maximum 2MeV Flux: 13357 pfu

Potential Impacts: Satellite systems may experience significant charging resulting in increased risk to satellite systems.

ALERT
Type IV Radio Emission
Issued: 20.04.2021 07.07 am UTC
Type IV Radio Emission
Begin Time: 2021 Apr 20 0000 UTC

Description: Type IV emissions occur in association with major eruptions on the sun and are typically associated with strong coronal mass ejections and solar radiation storms.

ALERT
Type II Radio Emission
Issued: 20.04.2021 07.06 am UTC
Type II Radio Emission
Begin Time: 2021 Apr 19 2339 UTC
Estimated Velocity: 750 km/s

Description: Type II emissions occur in association with eruptions on the sun and typically indicate a coronal mass ejection is associated with a flare event.

CONTINUED ALERT
Electron 2MeV Integral Flux exceeded 1000pfu
Issued: 20.04.2021 04.59 am UTC
Electron 2MeV Integral Flux exceeded 1000pfu
Continuation of Serial Number: 3133
Begin Time: 2021 Apr 17 1715 UTC
Yesterday Maximum 2MeV Flux: 10148 pfu

Potential Impacts: Satellite systems may experience significant charging resulting in increased risk to satellite systems.

EXTENDED WARNING
Geomagnetic K-index of 4 expected
Issued: 20.04.2021 04.31 am UTC
Geomagnetic K-index of 4 expected
Extension to Serial Number: 3886
Valid From: 2021 Apr 19 1924 UTC
Now Valid Until: 2021 Apr 20 1200 UTC
Warning Condition: Persistence

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

ALERT
Geomagnetic K-index of 4
Issued: 19.04.2021 09.06 pm UTC
Geomagnetic K-index of 4
Threshold Reached: 2021 Apr 19 2059 UTC
Synoptic Period: 1800-2100 UTC

Active Warning: Yes

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

WARNING
Geomagnetic K-index of 4 expected
Issued: 19.04.2021 07.22 pm UTC
Geomagnetic K-index of 4 expected
Valid From: 2021 Apr 19 1924 UTC
Valid To: 2021 Apr 20 0600 UTC
Warning Condition: Onset

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

CONTINUED ALERT
Electron 2MeV Integral Flux exceeded 1000pfu
Issued: 19.04.2021 09.41 am UTC
Electron 2MeV Integral Flux exceeded 1000pfu
Continuation of Serial Number: 3132
Begin Time: 2021 Apr 17 1715 UTC
Yesterday Maximum 2MeV Flux: 14078 pfu

Potential Impacts: Satellite systems may experience significant charging resulting in increased risk to satellite systems.

WARNING
Geomagnetic K-index of 5 expected
Issued: 19.04.2021 05.16 am UTC
Geomagnetic K-index of 5 expected
Valid From: 2021 Apr 19 0516 UTC
Valid To: 2021 Apr 19 1200 UTC
Warning Condition: Onset
NOAA Scale: G1 - Minor

Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

EXTENDED WARNING
Geomagnetic K-index of 4 expected
Issued: 19.04.2021 05.03 am UTC
Geomagnetic K-index of 4 expected
Extension to Serial Number: 3884
Valid From: 2021 Apr 18 2240 UTC
Now Valid Until: 2021 Apr 19 1500 UTC
Warning Condition: Persistence

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

ALERT
Geomagnetic K-index of 4
Issued: 19.04.2021 12.02 am UTC
Geomagnetic K-index of 4
Threshold Reached: 2021 Apr 18 2359 UTC
Synoptic Period: 2100-2400 UTC

Active Warning: Yes

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

WARNING
Geomagnetic K-index of 4 expected
Issued: 18.04.2021 10.42 pm UTC
Geomagnetic K-index of 4 expected
Valid From: 2021 Apr 18 2240 UTC
Valid To: 2021 Apr 19 0600 UTC
Warning Condition: Onset

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

EXTENDED WARNING
Geomagnetic K-index of 4 expected
Issued: 18.04.2021 07.10 am UTC
Geomagnetic K-index of 4 expected
Extension to Serial Number: 3882
Valid From: 2021 Apr 17 2330 UTC
Now Valid Until: 2021 Apr 18 1800 UTC
Warning Condition: Persistence

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

CONTINUED ALERT
Electron 2MeV Integral Flux exceeded 1000pfu
Issued: 18.04.2021 05.04 am UTC
Electron 2MeV Integral Flux exceeded 1000pfu
Continuation of Serial Number: 3131
Begin Time: 2021 Apr 17 1715 UTC
Yesterday Maximum 2MeV Flux: 1252 pfu

Potential Impacts: Satellite systems may experience significant charging resulting in increased risk to satellite systems.

ALERT
Geomagnetic K-index of 4
Issued: 17.04.2021 11.44 pm UTC
Geomagnetic K-index of 4
Threshold Reached: 2021 Apr 17 2344 UTC
Synoptic Period: 2100-2400 UTC

Active Warning: Yes

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

WARNING
Geomagnetic K-index of 4 expected
Issued: 17.04.2021 11.33 pm UTC
Geomagnetic K-index of 4 expected
Valid From: 2021 Apr 17 2330 UTC
Valid To: 2021 Apr 18 0900 UTC
Warning Condition: Onset

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

ALERT
Electron 2MeV Integral Flux exceeded 1000pfu
Issued: 17.04.2021 05.31 pm UTC
Electron 2MeV Integral Flux exceeded 1000pfu
Threshold Reached: 2021 Apr 17 1715 UTC
Station: GOES-16


Potential Impacts: Satellite systems may experience significant charging resulting in increased risk to satellite systems.

ALERT
Type II Radio Emission
Issued: 17.04.2021 05.26 pm UTC
Type II Radio Emission
Begin Time: 2021 Apr 17 1626 UTC
Estimated Velocity: 353 km/s

Description: Type II emissions occur in association with eruptions on the sun and typically indicate a coronal mass ejection is associated with a flare event.

WARNING
Geomagnetic K-Index of 6 expected
Issued: 17.04.2021 08.13 am UTC
Geomagnetic K-Index of 6 expected
Valid From: 2021 Apr 17 0812 UTC
Valid To: 2021 Apr 17 1200 UTC
Warning Condition: Onset
NOAA Scale: G2 - Moderate

Potential Impacts: Area of impact primarily poleward of 55 degrees Geomagnetic Latitude.
Induced Currents - Power grid fluctuations can occur. High-latitude power systems may experience voltage alarms.
Spacecraft - Satellite orientation irregularities may occur; increased drag on low Earth-orbit satellites is possible.
Radio - HF (high frequency) radio propagation can fade at higher latitudes.
Aurora - Aurora may be seen as low as New York to Wisconsin to Washington state.

ALERT
Geomagnetic K-index of 5
Issued: 17.04.2021 07.53 am UTC
Geomagnetic K-index of 5
Threshold Reached: 2021 Apr 17 0746 UTC
Synoptic Period: 0600-0900 UTC

Active Warning: Yes
NOAA Scale: G1 - Minor

Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

ALERT
Geomagnetic K-index of 5
Issued: 17.04.2021 06.01 am UTC
Geomagnetic K-index of 5
Threshold Reached: 2021 Apr 17 0559 UTC
Synoptic Period: 0300-0600 UTC

Active Warning: Yes
NOAA Scale: G1 - Minor

Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

EXTENDED WARNING
Geomagnetic K-index of 5 expected
Issued: 17.04.2021 05.33 am UTC
Geomagnetic K-index of 5 expected
Extension to Serial Number: 1593
Valid From: 2021 Apr 16 1925 UTC
Now Valid Until: 2021 Apr 17 1200 UTC
Warning Condition: Persistence

Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

EXTENDED WARNING
Geomagnetic K-index of 4 expected
Issued: 17.04.2021 05.33 am UTC
Geomagnetic K-index of 4 expected
Extension to Serial Number: 3880
Valid From: 2021 Apr 16 1335 UTC
Now Valid Until: 2021 Apr 17 1800 UTC
Warning Condition: Persistence

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

ALERT
Geomagnetic K-index of 5
Issued: 17.04.2021 02.02 am UTC
Geomagnetic K-index of 5
Threshold Reached: 2021 Apr 17 0200 UTC
Synoptic Period: 0000-0300 UTC

Active Warning: Yes
NOAA Scale: G1 - Minor

Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

Table

Date Radio flux 10.7 cm SESC Sunspot number Sunspot area 10E-6 New regions GOES15 X-ray Bkgd flux Flares
X-ray Optical
C M X S 1 2 3
16.04.2021 77 44 110 2 * 0 0 0 0 0 0 0
17.04.2021 75 28 30 0 * 0 0 0 0 0 0 0
18.04.2021 78 15 50 0 * 0 0 0 2 0 0 0
19.04.2021 86 36 180 1 * 0 1 0 6 0 0 0
20.04.2021 80 54 340 1 * 0 0 0 12 0 0 0
21.04.2021 78 47 320 0 * 1 0 0 4 0 0 0
22.04.2021 84 42 240 0 * 11 0 0 4 1 0 0
23.04.2021 77 29 100 0 * 6 0 0 2 0 0 0
24.04.2021 79 62 150 2 * 0 0 0 1 0 0 0
25.04.2021 79 57 160 1 * 1 0 0 2 0 0 0
26.04.2021 80 54 220 0 * 1 0 0 4 0 0 0
27.04.2021 79 47 140 0 * 0 0 0 0 0 0 0
28.04.2021 78 42 70 0 * 0 0 0 0 0 0 0
29.04.2021 77 37 70 0 * 0 0 0 0 0 0 0
30.04.2021 73 35 70 0 * 0 0 0 0 0 0 0
01.05.2021 72 11 10 0 * 0 0 0 0 0 0 0
02.05.2021 72 0 0 0 * 0 0 0 0 0 0 0
03.05.2021 72 0 0 0 * 0 0 0 0 0 0 0
04.05.2021 70 0 0 0 * 0 0 0 0 0 0 0
05.05.2021 70 0 0 0 * 0 0 0 0 0 0 0
06.05.2021 71 0 0 0 * 0 0 0 0 0 0 0
07.05.2021 75 15 130 1 * 0 1 0 2 1 0 0
08.05.2021 76 17 180 0 * 2 0 0 4 0 0 0
09.05.2021 76 18 180 0 * 3 0 0 4 0 0 0
10.05.2021 77 36 170 1 * 0 0 0 1 0 0 0
11.05.2021 76 31 230 0 * 0 0 0 0 0 0 0
12.05.2021 75 31 230 0 * 1 0 0 2 0 0 0
13.05.2021 75 24 110 0 * 0 0 0 2 0 0 0
14.05.2021 71 24 70 0 * 0 0 0 1 0 0 0
15.05.2021 73 24 60 0 * 0 0 0 0 0 0 0
Average/Total 76 29 121 9 26 2 0 53 2 0 0

Summary graph

Flares

Solar Wind

Solar Wind

The solar wind is a stream of plasma released from the upper atmosphere of the Sun. It consists of mostly electrons, protons and alpha particles with energies usually between 1.5 and 10 keV. The stream of particles varies in density, temperature, and speed over time and over solar longitude. These particles can escape the Sun's gravity because of their high energy, from the high temperature of the corona and magnetic, electrical and electromagnetic phenomena in it.

The solar wind is divided into two components, respectively termed the slow solar wind and the fast solar wind. The slow solar wind has a velocity of about 400 km/s, a temperature of 1.4–1.6×10e6 K and a composition that is a close match to the corona. By contrast, the fast solar wind has a typical velocity of 750 km/s, a temperature of 8×10e5 K and it nearly matches the composition of the Sun's photosphere. The slow solar wind is twice as dense and more variable in intensity than the fast solar wind. The slow wind also has a more complex structure, with turbulent regions and large-scale structures.

Solar radio flux at 10.7 cm

Solar radio flux at 10.7 cm

The solar radio flux at 10.7 cm (2800 MHz) is an excellent indicator of solar activity. Often called the F10.7 index, it is one of the longest running records of solar activity. The F10.7 radio emissions originates high in the chromosphere and low in the corona of the solar atmosphere. The F10.7 correlates well with the sunspot number as well as a number of UltraViolet (UV) and visible solar irradiance records. Reported in “solar flux units”, (s.f.u.), the F10.7 can vary from below 50 s.f.u., to above 300 s.f.u., over the course of a solar cycle.

Flares

Flares

A solar flare is a sudden flash of brightness observed over the Sun's surface or the solar limb, which is interpreted as a large energy release of up to 6 × 10e25 joules of energy. They are often, but not always, followed by a colossal coronal mass ejection. The flare ejects clouds of electrons, ions, and atoms through the corona of the sun into space. These clouds typically reach Earth a day or two after the event.

Solar flares affect all layers of the solar atmosphere (photosphere, chromosphere, and corona), when the plasma medium is heated to tens of millions of kelvin, while the electrons, protons, and heavier ions are accelerated to near the speed of light. They produce radiation across the electromagnetic spectrum at all wavelengths, from radio waves to gamma rays, although most of the energy is spread over frequencies outside the visual range and for this reason the majority of the flares are not visible to the naked eye and must be observed with special instruments. Flares occur in active regions around sunspots, where intense magnetic fields penetrate the photosphere to link the corona to the solar interior. Flares are powered by the sudden (timescales of minutes to tens of minutes) release of magnetic energy stored in the corona. The same energy releases may produce coronal mass ejections (CME), although the relation between CMEs and flares is still not well established.

The frequency of occurrence of solar flares varies, from several per day when the Sun is particularly "active" to less than one every week when the Sun is "quiet", following the 11-year cycle (the solar cycle). Large flares are less frequent than smaller ones.

Classification

Solar flares are classified as A, B, C, M or X according to the peak flux (in watts per square metre, W/m2) of 100 to 800 picometre X-rays near Earth, as measured on the GOES spacecraft.

Classification Peak Flux Range at 100-800 picometer
W/m2
A < 10e-7
B 10e-7 to 10e-6
C 10e-6 to 10e-5
M 10e-5 to 10e-4
X 10e-4 to 10e-3
Z > 10e-3

An earlier flare classification is based on Hα spectral observations. The scheme uses both the intensity and emitting surface. The classification in intensity is qualitative, referring to the flares as: (f)aint, (n)ormal or (b)rilliant. The emitting surface is measured in terms of millionths of the hemisphere and is described below. (The total hemisphere area AH = 6.2 × 1012 km2.)

Classification Corrected area
(millionths of hemisphere)
S < 100
1 100 - 250
2 250 - 600
3 600 - 1200
4 > 1200

Sunspot number

Sunspots

Sunspots are temporary phenomena on the photosphere of the Sun that appear visibly as dark spots compared to surrounding regions. They correspond to concentrations of magnetic field that inhibit convection and result in reduced surface temperature compared to the surrounding photosphere. Sunspots usually appear in pairs, with pair members of opposite magnetic polarity. The number of sunspots varies according to the approximately 11-year solar cycle.

Sunspot populations quickly rise and more slowly fall on an irregular cycle of 11 years, although significant variations in the number of sunspots attending the 11-year period are known over longer spans of time. For example, from 1900 to the 1960s, the solar maxima trend of sunspot count has been upward; from the 1960s to the present, it has diminished somewhat. Over the last decades the Sun has had a markedly high average level of sunspot activity; it was last similarly active over 8,000 years ago.

The number of sunspots correlates with the intensity of solar radiation over the period since 1979, when satellite measurements of absolute radiative flux became available. Since sunspots are darker than the surrounding photosphere it might be expected that more sunspots would lead to less solar radiation and a decreased solar constant. However, the surrounding margins of sunspots are brighter than the average, and so are hotter; overall, more sunspots increase the Sun's solar constant or brightness. The variation caused by the sunspot cycle to solar output is relatively small, on the order of 0.1% of the solar constant (a peak-to-trough range of 1.3 W/m2 compared to 1366 W/m2 for the average solar constant).

K-indices



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1 0 1 2 2 1



Data


Estimated Planetary

Estimated Planetary

Date A K-indices (UTC)
0h 3h 6h 9h 12h 15h 18h 21h
17.04.2021 29 5 5 5 4 4 3 3 4
18.04.2021 16 4 4 3 3 2 2 3 4
19.04.2021 18 4 4 3 3 3 3 4 3
20.04.2021 13 3 3 2 3 2 2 3 3
21.04.2021 7 2 3 2 2 2 0 1 1
22.04.2021 5 2 2 2 2 2 0 0 2
23.04.2021 15 3 3 3 2 1 3 3 5
24.04.2021 10 3 3 2 2 2 1 2 3
25.04.2021 20 5 4 3 3 3 2 3 2
26.04.2021 14 4 5 3 1 2 1 1 2
27.04.2021 8 3 3 2 2 1 1 0 1
28.04.2021 3 2 1 1 1 1 0 0 1
29.04.2021 6 2 2 2 2 2 1 2 1
30.04.2021 6 1 2 1 1 1 2 2 2
01.05.2021 5 2 1 1 2 1 1 1 2
02.05.2021 10 3 3 3 1 1 2 2 2
03.05.2021 5 2 1 2 2 1 1 1 1
04.05.2021 4 2 1 1 1 1 0 1 1
05.05.2021 2 1 1 0 0 1 0 1 1
06.05.2021 4 1 1 1 1 2 1 1 0
07.05.2021 3 0 1 0 0 1 1 1 1
08.05.2021 3 1 0 1 2 1 0 0 0
09.05.2021 4 0 1 1 0 1 1 0 2
10.05.2021 6 2 2 2 2 2 1 2 2
11.05.2021 3 2 1 1 1 1 1 0 0
12.05.2021 41 1 1 4 4 7 7 3 3
13.05.2021 7 2 2 2 2 2 1 2 2
14.05.2021 4 0 1 1 1 1 1 2 2
15.05.2021 8 3 1 3 2 1 1 1 1
16.05.2021 4 1 0 1 2 2 1

Middle Latitude

Date A K-indices
17.04.2021 20 3 4 5 3 3 2 2 4
18.04.2021 13 3 3 3 3 2 2 3 3
19.04.2021 15 3 3 3 3 3 3 3 3
20.04.2021 10 3 3 2 2 2 1 2 3
21.04.2021 7 2 3 2 2 2 1 1 1
22.04.2021 4 1 1 2 1 2 0 1 2
23.04.2021 15 3 2 3 3 2 3 3 4
24.04.2021 10 3 3 3 2 2 0 2 3
25.04.2021 16 5 3 3 3 3 1 2 2
26.04.2021 12 4 4 3 1 2 1 2 2
27.04.2021 8 3 3 2 2 2 1 1 1
28.04.2021 4 2 0 0 2 2 1 1 1
29.04.2021 5 2 2 1 1 2 1 2 1
30.04.2021 6 1 1 1 1 1 2 3 2
01.05.2021 6 1 1 2 3 1 1 1 2
02.05.2021 12 3 3 3 2 2 2 3 3
03.05.2021 6 2 2 2 2 2 2 1 1
04.05.2021 5 2 1 1 1 2 1 2 1
05.05.2021 3 0 0 0 1 2 1 2 1
06.05.2021 2 1 1 0 1 2 0 1 0
07.05.2021 3 0 0 0 1 2 1 2 1
08.05.2021 4 1 0 1 2 2 1 1 1
09.05.2021 6 0 0 0 1 4 2 1 2
10.05.2021 8 2 2 2 2 3 1 2 2
11.05.2021 4 2 1 1 1 2 1 1 0
12.05.2021 25 1 0 4 4 6 5 2 2
13.05.2021 7 2 2 2 2 2 2 2 2
14.05.2021 4 0 1 1 1 1 2 1 2
15.05.2021 8 3 2 3 2 2 2 1 1
16.05.2021 1 0 1 2 2 1

High Latitude

Date A K-indices
17.04.2021 57 5 4 6 7 6 5 3 3
18.04.2021 36 3 3 5 7 5 2 2 2
19.04.2021 47 3 3 5 7 5 5 5 3
20.04.2021 26 3 3 5 6 3 3 3 2
21.04.2021 16 1 2 5 5 3 1 1 0
22.04.2021 9 1 2 3 4 3 1 0 0
23.04.2021 13 1 3 3 4 2 3 1 3
24.04.2021 20 3 3 4 6 3 1 0 2
25.04.2021 40 5 5 4 6 6 3 3 2
26.04.2021 18 3 5 4 3 4 1 1 1
27.04.2021 15 1 3 5 4 3 2 0 1
28.04.2021 2 1 1 0 1 1 0 0 0
29.04.2021 4 0 0 2 3 2 0 0 0
30.04.2021 1 0 0 0 0 0 1 1 1
01.05.2021 2 0 0 1 2 1 0 1 0
02.05.2021 7 2 3 3 2 1 0 1 1
03.05.2021 3 2 1 2 2 0 0 0 0
04.05.2021 3 2 0 0 2 0 0 1 1
05.05.2021 0 0 0 0 0 0 0 0 0
06.05.2021 4 1 1 1 1 3 1 0 0
07.05.2021 1 0 0 0 0 0 1 1 0
08.05.2021 3 1 0 0 3 2 0 0 0
09.05.2021 1 0 1 0 0 1 1 0 0
10.05.2021 6 1 3 1 2 1 1 2 1
11.05.2021 1 2 1 0 0 0 0 0 0
12.05.2021 47 1 0 5 4 7 7 2 2
13.05.2021 6 3 3 1 1 1 1 1 1
14.05.2021 3 1 1 1 1 0 1 1 2
15.05.2021 3 1 4 3
16.05.2021 0 0 4 3 0

About

The K-index quantifies disturbances in the horizontal component of earth's magnetic field with an integer in the range 0–9 with 1 being calm and 5 or more indicating a geomagnetic storm. It is derived from the maximum fluctuations of horizontal components observed on a magnetometer during a three-hour interval. The label K comes from the German word Kennziffer meaning “characteristic digit”. The K-index was introduced by Julius Bartels in 1938.

The Estimated 3-hour Planetary Kp-index is derived at the NOAA Space Weather Prediction Center using data from the following ground-based magnetometers:

  • Sitka, Alaska
  • Meanook, Canada
  • Ottawa, Canada
  • Fredericksburg, Virginia
  • Hartland, UK
  • Wingst, Germany
  • Niemegk, Germany
  • Canberra, Australia

These data are made available thanks to the cooperative efforts between SWPC and data providers around the world, which currently includes the U.S. Geological Survey, Natural Resources Canada (NRCAN), the British Geological Survey, the German Research Centre for Geosciences (GFZ), and Geoscience Australia. Important magnetometer observations are also contributed by the Institut de Physique du Globe de Paris and the Korean Space Weather Center K-index Watches are issued when the highest predicted NOAA estimated Kp-indices for a day are K = 5, 6, 7, or >= 8 and is reported in terms of the NOAA G scale. K-index Warnings are issued when NOAA estimated Kp-indices of 4, 5, 6, and 7 or greater are expected. K-index Alerts are issued when the NOAA estimated Kp-indices reach 4, 5, 6, 7, 8, or 9.


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