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| Warnings and Alerts | |
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Issue Time: 2026 May 20 1006 UTC
CONTINUED ALERT: Electron 2MeV Integral Flux exceeded 1000pfu Continuation of Serial Number: 3689 Begin Time: 2026-05-16 17:40 Yesterday Maximum 2MeV Flux: 2860 pfu Continued 2026-05-20 10:06 by Forecaster User Space Weather Scales |
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| Current Condition and Alerts | |
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Issued: 2026 May 20 1205 UTC
Prepared
by the US Dept. of Commerce, NOAA, Space Weather Prediction
Center
Geophysical Alert Message Solar-terrestrial indices for 19 May follow. Solar flux 106 and estimated planetary A-index 19. The estimated planetary K-index at 1200 UTC on 20 May was 1.00. No space weather storms were observed for the past 24 hours. No space weather storms are predicted for the next 24 hours. Space Weather Scales |
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| Forecast Discussion | |
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Issued: 2026 May 20 1230 UTC
Prepared
by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction
Center
Solar Activity .24 hr Summary... Solar activity continued at low levels during the reporting period. The largest events were a C2.1/Sf flare at 19/1920 UTC and a C1.4 flare at 19/2203 UTC, both from Region 4436 (N18W71, Cso/beta). This region was responsible for the majority of the periods activity, which otherwise consisted of occasional low-level B-class flaring. There are currently five numbered regions on the visible disk. Most regions continued to show gradual decay, with a few exhibiting localized development. Region 4436 transitioned into a well-defined bipolar group following a phase of stability, characterized by new flux emergence and consolidation within its trailing spots of opposite polarity. Region 4439 (N06E23, Cao/beta) remained mostly stable, though slight divergence was observed in its trailing spots. Region 4440 remained a stable unipolar group. Region 4441 (N07W22, Dao/beta) showed mild overall growth after new flux emerged between the leading and trailing spots, immediately consolidating with the like-polarity poles. Region 4443 (S16E30, Axx/alpha) experienced continued decay to a single unipolar spot. A CME associated with the B8.2 flare from Region 4440 was observed off the northeast limb, first appearing in LASCO C2 imagery at 19/1101 UTC. Analysis indicates this ejecta is not Earth-directed. No other Earth-directed CMEs were observed in available coronagraph imagery. .Forecast... Solar activity is expected to remain at low levels through 21 May, with a slight chance for isolated M-class flares (R1-R2/Minor-Moderate) primarily due to the complexity of Region 4441 and the recent flaring history of Region 4436. An increase in activity is anticipated starting 22 May as multiple active regions, tracked via far-side satellite and helioseismology imagery, rotate into view. Energetic Particle .24 hr Summary... The greater than 2 MeV electron flux at geosynchronous orbit remained at high levels, reaching a peak flux of 2,860 pfu observed at 19/1650 UTC. The greater than 10 MeV proton flux at geosynchronous orbit remained at background levels. .Forecast... The greater than 2 MeV electron flux is expected to return to normal to moderate levels through 21 May as current conditions wane. A return to high levels is anticipated on 22 May following the geoeffective onset of a new coronal hole high-speed stream. The greater than 10 MeV proton flux is expected to remain at background levels through 22 May. Solar Wind .24 hr Summary... Solar wind parameters trended toward background conditions with wind speeds around 475 km/s, Total field strength decreased to 4 nT, and Bz becoming mostly northward. Phi has continued in a negative orientation. .Forecast... Solar wind parameters are expected to continue trending toward nominal conditions through early on 21 May. Mild enhancements are likely on 21 May from a solar sector boundary crossing, with more pronounced high-speed stream conditions expected on 22 May due to the onset of a positive polarity coronal hole high-speed stream (+CH HSS). Geospace .24 hr Summary... The geomagnetic field was initially at active levels before becoming quiet to unsettled as parameters waned. .Forecast... Geomagnetic field activity is expected to be at mostly quiet to unsettled levels over 20–21 May as enhancements wane. Isolated active periods are likely expected on 22 May following the onset of the approaching +CH HSS. Space Weather Scales |
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| Three Day Forecast | |
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Issued: 2026 May 20 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 4 (below NOAA Scale levels). The greatest expected 3 hr Kp for May 20-May 22 2026 is 3.67 (below NOAA Scale levels). NOAA Kp index breakdown May 20-May 22 2026 May 20 May 21 May 22 00-03UT 3.00 2.67 2.67 03-06UT 2.67 2.00 3.67 06-09UT 2.00 2.33 2.00 09-12UT 2.00 2.33 0.67 12-15UT 2.00 2.33 1.67 15-18UT 2.00 2.33 1.67 18-21UT 2.00 2.33 2.33 21-00UT 2.00 2.67 2.33 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-19 over the past 24 hours, was below S-scale storm level thresholds. Solar Radiation Storm Forecast for May 20-May 22 2026 May 20 May 21 May 22 S1 or greater 5% 5% 5% 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 20-May 22 2026 May 20 May 21 May 22 R1-R2 20% 20% 25% R3 or greater 5% 5% 5% Rationale: There is a slight chance for R1-R2 (Minor-Moderate) radio blackouts through 21 May, increasing to a chance on 22 May. R3 (Strong) or greater events are not expected. Space Weather Scales |
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| Weekly Highlights and Forecasts | |
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Issued: 2026 May 18 0431 UTC
Prepared
by the US Dept. of Commerce, NOAA, Space Weather Prediction
Center
Highlights of Solar and Geomagnetic Activity 11 - 17 May 2026 Solar activity reached moderate levels on 16 May due to four M-class flares. The largest were an M1.9/2N (R1-Minor) at 16/1612UTC from Region 4436 (N18, L=330, class/area=Dao/200 on 11 May) and a second M1.9 flare (R1-Moderate) at 16/1742UTC from Region 4435 (N22, L=040, class/area=Dao/070 on 15 May). The 1612UTC M1.9 was associated with a Type IV radio sweep, two 10.7 cm radio bursts, and a filament eruption that was centered at approximately N21W07, which lead to a complex CME signature in coronagraph imagery. The first front was first seen in LASCO C2 imagery at 16/1636UTC, and the second front became visible at approximately 16/1700 UTC. Analysis and modeling of the event suggests potential for a glancing blow at Earth by mid UTC-day on 18 May, with the bulk of the material passing northward of Earth's orbit. The other two M-flares, an M1.4 at 17/0339UTC and an M1.3 at 16/1629, were also from Regions 4435 and 4436, with the M1.3 following on the heels of the 16/1612UTC M1.9. The other 11 numbered active regions on this visible disk were either quiet or only produced C-class activity during the past week. 3 Type II radio sweeps and an additional 10.7cm radio burst were observed during the summary period, but they were not associated with any Earth-directed activity No proton events were observed at geosynchronous orbit. The greater than 2 MeV electron flux at geosynchronous orbit was at normal to moderate levels for the majority of the summary period, before increasing to high levels at 16/1740UTC. During the summary period, the maximum value reached was 6,120 pfu at 17/1740UTC. Geomagnetic field activity reached G1-G2 (Minor-Moderate) geomagnetic storming levels on 15-16 May due to a negative polarity coronal hole high speed stream becoming geoeffective late on 15 May. Total magnetic field strength, Bt, increased all throughout 15 May, from approximately 3 nT to a peak of 17 nT at 15/1555UTC. The north-south component, Bz, rotated between +/- 11 nT, with maximum southward deflections of approximately -13 nT. The interplanetary magnetic field had returned to background levels by the end of 16 May. A smaller positive polarity coronal hole high speed stream became geoeffective on 13 May with a max Bt of 13 nT and maximum Bz southward deflection of -9 nT; however this only produced unsettled geomagnetic conditions and no NOAA Geomagnetic Storming thresholds were reached. Forecast of Solar and Geomagnetic Activity 18 May - 13 June 2026 Solar activity is expected to be at low to moderate levels throughout the outlook period, with M-class activity (R1-R2, Minor-Moderate) ranging from a chance to likely and X-class activity (R3, Strong) ranging from a slight chance to a chance, due to the flare potential of several active regions currently on the visible disk and those both expected to return and indicated by Solar Orbiter magnetic imagery. No proton events are expected at geosynchronous orbit. The greater than 2 MeV electron flux at geosynchronous orbit is expected to be at high levels on 18 May and 21-23 May due to influence from the current negative polarity coronal hole high speed stream and an anticipated solar sector boundary cross on 21 May. The remaining days of the outlook period are likely to be at normal to moderate levels. Geomagnetic field activity is expected to reach G1 (Minor) geomagnetic storming levels over 18-19 May due to potential influences from the CME that left the Sun on 16 May arriving in the near-Earth environment in the midst of the current high speed stream. The remainder of the outlook period is anticipated to be at largely quiet to unsettled levels. Space Weather Scales |
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| 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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| Daily Video HMI Continuum | |
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| Daily Video 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 | |
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| 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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