Geomagnetic Storm Threat This Week

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast SDF Number 271 Issued at 2200Z on 28 Sep 2014 IA.

Analysis of Solar Active Regions and Activity from 27/2100Z to 28/2100Z: Solar activity has been at high levels for the past 24 hours.

The largest solar event of the period was a M5 event observed at 28/0258Z from Region 2173 (S17W39). There are currently 7 numbered sunspot regions on the disk. IB.

Solar Activity Forecast: Solar activity is expected to be moderate with a slight chance for an X-class flare on days one, two, and three (29 Sep, 30 Sep, 01 Oct).

IIA. Geophysical Activity Summary 27/2100Z to 28/2100Z: The geomagnetic field has been at quiet to unsettled levels for the past 24 hours. Solar wind speed, as measured by the ACE spacecraft, reached a peak speed of 452 km/s at 28/1113Z.

Total IMF reached 6 nT at 27/2101Z. The maximum southward component of Bz reached -5 nT at 28/0949Z.

Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 1208 pfu. IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to unsettled levels on days one and two (29 Sep, 30 Sep) and quiet levels on day three (01 Oct)

Protons have a slight chance of crossing threshold on days one through three (29 Sep - 01 Oct) III. Event probabilities 29 Sep-01 Oct Class M 75/75/75 Class X 20/20/20 Proton 15/20/20 PCAF green IV. Penticton 10.7 cm Flux Observed 28 Sep 181 Predicted 29 Sep-01 Oct 185/190/195 90 Day Mean 28 Sep 135 V. Geomagnetic A Indices Observed Afr/Ap 27 Sep 012/016 Estimated Afr/Ap 28 Sep 009/009 Predicted Afr/Ap 29 Sep-01 Oct 007/010-007/010-007/008 VI.

Geomagnetic Activity Probabilities 29 Sep-01 Oct A. Middle Latitudes Active 25/25/20 Minor Storm 10/10/05 Major-severe storm 01/01/01 B. High Latitudes Active 15/15/15 Minor Storm 25/25/25 Major-severe storm 35/35/25