Viewing archive of Friday, 25 October 2013

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2013 Oct 25 1255 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Active conditions expected (A>=20 or K=4)

Solar protons

Warning condition (activity levels expected to increase, but no numeric forecast given)

	10cm flux	Ap
25 Oct 2013	166	005
26 Oct 2013	166	011
27 Oct 2013	161	016

Bulletin

New beta region NOAA AR 11882 near the East limb produced one X flare, two M flares, and one C flare during the past 24 hours. During the same period, eight C flares were released by NOAA AR 11875 (beta-gamma-delta) and 11877 (beta-gamma). The X1.7 flare peaked at 08:01 UT on October 25, and caused a Type II radio burst with estimated shock speed of 1240 km/s as observed by the San Vito solar observatory. SDO/AIA observed a filament eruption in the NE around 2:59 UT on October 25. In the next 48 hours, X flares are possible, especially from NOAA AR 11882. There is a substantial risk of halo CMEs and the warning condition for proton storms remains valid. In the past 24 hours, solar wind has varied between about 300 and 350 km/s. In the same period, the Interplanetary Magnetic Field has decreased from about 7 to 2 nT. A weak glancing blow from the CME from October 22 (4:36 UT) seems to have happened around 4h UT on October 25, without any geomagnetic effects. Strong CMEs were registered by LASCO C2 on October 24 (17:24 UT) and October 25 (3:24 UT, related to the M2.9 flare; 4:48 UT, related to the filament eruption; 8:24 UT, related to the X1.7 flare). Preliminary analysis suggests that these CMEs will not be geo-effective. Geomagnetic activity was at quiet levels (K Dourbes between 0 and 3; NOAA Kp between 0 and 1) during the past 24 hours. Quiet conditions (K Dourbes < 4) are expected for October 25 and the first half of October 26. Active conditions (K Dourbes = 4) with isolated minor storm intervals (K Dourbes = 5) are possible in the second half of October 26 and on October 27, due to the expected arrival of the CME from October 22 (observed by LASCO C2 at 21:20 UT).

Today's estimated international sunspot number (ISN): 097, based on 11 stations.

Solar indices for 24 Oct 2013

Wolf number Catania	157
10cm solar flux	161
AK Chambon La Forêt	005
AK Wingst	002
Estimated Ap	002
Estimated international sunspot number	105 - Based on 19 stations

Noticeable events summary

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

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