| Warnings |
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Space Weather Message Code: WARK06
Serial
Number: 577
Issue
Time: 2025 Apr 21 1354 UTC
WARNING: Geomagnetic K-Index of 6 expected Valid From: 2025 Apr 21 1353 UTC Valid To: 2025 Apr 21 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. -------------------------------------------------------------------------------- Space Weather Message Code: ALTK05 Serial Number: 1755 Issue Time: 2025 Apr 21 1354 UTC ALERT: Geomagnetic K-index of 5 Threshold Reached: 2025 Apr 21 1352 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. Space Weather Scales |
| Current Condition and Alerts |
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Issued: 2025 Apr 21 1205 UTC
Prepared
by the US Dept. of Commerce, NOAA, Space Weather Prediction
Center
Geophysical Alert Message Solar-terrestrial indices for 20 April follow. Solar flux 156 and estimated planetary A-index 14. The estimated planetary K-index at 1200 UTC on 21 April was 4.67. Space weather for the past 24 hours has been minor. Geomagnetic storms reaching the G1 level occurred. Radio blackouts reaching the R1 level occurred. Space weather for the next 24 hours is predicted to be minor. Geomagnetic storms reaching the G1 level are expected. Space Weather Scales |
| Forecast Discussion |
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Issued: 2025 Apr 21 1230 UTC
Prepared
by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction
Center
Solar Activity .24 hr Summary... Solar activity reached moderate levels. New Region 4068 (S06E72, Cso/beta) produced an M1.0 flare (R1-Minor) at 20/1211 UTC, the largest of the period. Only minor changes were observed in the numbered active regions on the visible disk. No Earth-directed CMEs were observed in available coronagraph imagery. .Forecast... Solar activity is expected to be low with a chance of M-class flares (R1-R2, Minor-Moderate) over 21-23 Apr. Energetic Particles .24 hr Summary... The greater than 2 MeV electron flux was at normal to moderate levels and the greater than 10 MeV proton flux was at background levels. .Forecast... The greater than 2 MeV electron flux is like to reach high levels over 21-23 Apr. The greater than 10 MeV proton flux is expected to continue at background levels. Solar Wind .24 hr Summary... Solar wind parameters were mildly enhanced through about 21/0600 UTC. Total magnetic field strength was between 6-16 nT. The Bz component briefly reached as far as -10 nT. Solar wind speeds were mostly between ~380-435 km/s. Phi angle was predominantly positive. After 21/0600 UTC, Bt increased to about 19 nT and the Bz component varied between +/-12 nT. Solar wind increased to about 650 km/s. .Forecast... Solar wind parameters are likely to contain enhancements on 21-23 Apr due to the anticipated influence from a large, recurrent, positive polarity corona hole in the Suns southern hemisphere. Geospace .24 hr Summary... The geomagnetic field was at unsettled to active levels. .Forecast... The geomagnetic field is expected to range from quiet to active levels on 21 Apr. G1-G2 (Minor-Moderate) geomagnetic storm levels are likely on 22-23 Apr due to the anticipated influence of a positive polarity CH HSS. Space Weather Scales |
| Three Day Forecast |
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Issued: 2025 Apr 21 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 5 (NOAA Scale G1). The greatest expected 3 hr Kp for Apr 21-Apr 23 2025 is 6.00 (NOAA Scale G2). NOAA Kp index breakdown Apr 21-Apr 23 2025 Apr 21 Apr 22 Apr 23 00-03UT 4.33 3.00 4.00 03-06UT 4.33 2.00 5.67 (G2) 06-09UT 4.33 3.00 4.33 09-12UT 4.67 (G1) 4.00 4.00 12-15UT 3.33 4.33 4.67 (G1) 15-18UT 2.67 5.00 (G1) 4.33 18-21UT 2.67 5.33 (G1) 3.00 21-00UT 2.67 6.00 (G2) 4.67 (G1) Rationale: Periods of G1-G2 (Minor-Moderate) geomagnetic storms are likely on 21-23 Apr due to the influences of a positive polarity CH HSS. B. NOAA Solar Radiation Activity Observation and Forecast Solar radiation, as observed by NOAA GOES-18 over the past 24 hours, was below S-scale storm level thresholds. Solar Radiation Storm Forecast for Apr 21-Apr 23 2025 Apr 21 Apr 22 Apr 23 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 Apr 21-Apr 23 2025 Apr 21 Apr 22 Apr 23 R1-R2 40% 40% 40% R3 or greater 5% 5% 5% Rationale: There is a chance for R1-R2 (Minor-Moderate) radio blackouts over 21-23 Apr. Space Weather Scales |
| Weekly Highlights and Forecasts |
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Issued: 2025 Apr 21 0125 UTC
Prepared
by the US Dept. of Commerce, NOAA, Space Weather Prediction
Center
Highlights of Solar and Geomagnetic Activity 14 - 20 April 2025 Solar activity reached moderate levels due to M-class flare activity on 14-15, 18 and 20 Apr. The largest event of the period was an M4.4 flare at 18/2350 UTC from an unseen source beyond the SE limb. No Earth-directed CMEs resulted from this week's solar activity. No proton events were observed at geosynchronous orbit. The greater than 2 MeV electron flux at geosynchronous orbit reached high levels on 14 Apr, with normal to moderate levels observed over 15-20 Apr. Geomagnetic field activity began the period at quiet to active levels in response to negative polarity CH HSS influences on 14 Apr. Periods of G1-G2 (Minor-Moderate) storming was observed on 15 Apr, with periods of G1-G4 (Minor-Severe) storming observed on 16 Apr, due to the passage of a CME that left the Sun on 13 Apr. Remnant CME influences and bouts of southward IMF persisted on 17-18 Apr with quiet to active levels observed. Quiet to active levels were observed on 19 Apr, and quiet to G1 (Minor) levels were observed on 20 Apr, in response to prolonged periods of southward Bz. Forecast of Solar and Geomagnetic Activity 21 April - 17 May 2025 Solar activity is expected to be predominately low with a varying chance for M-class (R1-R2/Minor-Moderate) flares throughout the forecast period. No proton events are expected at geosynchronous orbit, barring significant flare activity. The greater than 2 MeV electron flux at geosynchronous orbit is likely to reach high levels on 21-28 Apr, and 03-12 May. Normal to moderate levels are expected to prevail throughout the remainder of the period. Geomagnetic field activity is likely to reach G2 (Moderate) levels on 22-23 Apr, and G1 (Minor) levels on 24-25 Apr, due to the anticipated influence of a positive polarity CH HSS. Periods of G1 storms are likely on 01 May, and periods of G2 storms are likely on 02 May, due negative polarity CH HSS influences. The geomagnetic field is likely to reach G1 storm levels again over 05-11 May due to the influences of another negative polarity CH HSS. Space Weather Scales |
| About AIA Images |
| The Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO) is designed to provide an unprecedented view of the solar corona, taking images that span at least 1.3 solar diameters in multiple wavelengths nearly simultaneously, at a resolution of ~ 1 arcsec and at a cadence of 10 s or better. The primary goal of the AIA Science Investigation is to use these data, together with data from other SDO instruments and from other observatories, to significantly improve our understanding of the physics behind the activity displayed by the Sun's atmosphere, which drives space weather in the heliosphere and in planetary environments. The AIA will produce data required for quantitative studies of the evolving coronal magnetic field, and the plasma that it holds, both in quiescent phases and during flares and eruptions; the AIA science investigation aims to utilize these data in a comprehensive research program to provide new understanding of the observed processes Left Click Image for screen size, Right Click Image and open in new tab for full size. |
| Daily Image AIA 171 |
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| Daily Image AIA 171 PFSS Model |
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| Daily Image AIA 193 |
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| Daily Image AIA 304 |
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| Daily Video AIA 171 |
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| Daily Video AIA 171 PFSS Model |
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| Daily Video AIA 193 |
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| Daily Video AIA 304 |
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| About the HMI Images |
| (Helioseismic and Magnetic Imager) HMI is an instrument designed to study oscillations and the magnetic field at the solar surface, or photosphere. HMI is one of three instruments on the Solar Dynamics Observatory; together, the suite of instruments observes the Sun nearly continuously and takes a terabyte of data a day. HMI observes the full solar disk at 6173 Å with a resolution of 1 arcsecond. HMI is a successor to the Michelson Doppler Imager on the Solar and Heliospheric Observatory. This is very much how the Sun looks like in the visible range of the spectrum (for example, looking at it using special 'eclipse' glasses: Remember, do not ever look directly at the Sun!). The magnetogram image shows the magnetic field in the solar photosphere, with black and white indicating opposite polarities. Left Click Image for screen size, Right Click Image and open in new tab for full size. |
| Daily Image HMI Continuum |
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| Daily Image HMI Magnetogram |
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| About LASCO Images |
| LASCO (Large Angle Spectrometric Coronagraph) is able to take images of the solar corona by blocking the light coming directly from the Sun with an occulter disk, creating an artificial eclipse within the instrument itself. The position of the solar disk is indicated in the images by the white circle. The most prominent feature of the corona are usually the coronal streamers, those nearly radial bands that can be seen both in C2 and C3. Occasionally, a coronal mass ejection can be seen being expelled away from the Sun and crossing the fields of view of both coronagraphs. The shadow crossing from the lower left corner to the center of the image is the support for the occulter disk. C2 images show the inner solar corona up to 8.4 million kilometers (5.25 million miles) away from the Sun. C3 images have a larger field of view: They encompass 32 diameters of the Sun. To put this in perspective, the diameter of the images is 45 million kilometers (about 30 million miles) at the distance of the Sun, or half of the diameter of the orbit of Mercury. Many bright stars can be seen behind the Sun. Left Click Image for screen size, Right Click Image and open in new tab for full size. |
| Combined C2 C3 and AIA 304 |
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| Log Polar View C2 C3 and AIA 304 |
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| Combined C2 C3 and AIA 304 Video |
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| Log Polar View C2 C3 and AIA 304 Video |
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| Space Weather Videos |
| Space Weather Information |
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Demystifying
Space Weather
An article by Scientific Frontline Informative information and glossary about “Space Weather” Space weather has become increasingly important in our modern world due to our growing reliance on technology. It can impact various aspects of our daily lives, from communication and navigation systems to power grids and even astronaut safety. In this deep dive, we'll explore the intricacies of space weather, its causes, its effects, and why understanding it is crucial in our technology-dependent society. |
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