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Daily bulletin on solar and geomagnetic activity from the SIDC

Emesso: 2017 Jul 18 1241 UTC

SIDC Forecast

Brillamenti solari

C-class flares expected, (probability >=50%)

Geomagnetism

Quiet (A<20 and K<4)

Protoni solari

Quiet

	10cm flux	Ap
18 Jul 2017	084	015
19 Jul 2017	083	017
20 Jul 2017	083	007

Bulletin

NOAA region 2665 (Catania group 36) produced several C flares and is now located at the West limb. The largest was a C2.0 flare peaking at 00:40UT. As the region is disappearing behind the limb we still anticipate some related C flaring and a chance for an M flare but by the end of the period the region should have passed well around the limb. In SoHO/LASCO C2 a Westbound CME was visible from around 17:00UT onwards. It originated from NOAA region 2665 and was associated to along duration C1.2 flare. The CME had a limited angular extent and it is judged not to be Earth effective. Proton flux levels are at background values and expected to remain so.

Solar wind conditions showed the passage of the wake of the July 14 CME. Total magnetic field remained near 10nT for most of the period before dropping to nominal levels under 4nT around 9:00UT. Solar wind speed was mostly around 520 km/s before increasing to over 600 km/s around 9:00UT with values reaching over 650km/s. This thus seems to mark a transition into a fast solar wind regime around 9:00UT which is possibly due to the negative polarity coronal hole that passed the central meridian on July 14 in the southern hemisphere. Over the next 24-48 hours solar wind is expected to slowly recover towards nominal solar wind conditions. Geomagnetic conditions were mostly quiet to active (local K Dourbes 2-4) while the planetary NOAA Kp reached one isolated episode of moderate storm condition in the wake of the CME passage. With current high solar wind speed but nominal magnetic field values unsettled conditions are expected with isolated active periods possible. As Solar wind speed decreases quiet to unsettled conditions are expected later on.

Today's estimated international sunspot number (ISN): 000, based on 24 stations.

Solar indices for 17 Jul 2017

Wolf number Catania	025
10cm solar flux	086
AK Chambon La Forêt	024
AK Wingst	024
Estimated Ap	026
Estimated international sunspot number	021 - Based on 33 stations

Noticeable events summary

Provided by the Solar Influences Data analysis Center© - SIDC - Processed by SpaceWeatherLive

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