Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 18 April 2017

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 108 Issued at 2200Z on 18 Apr 2017

IA.  Analysis of Solar Active Regions and Activity from 17/2100Z to 18/2100Z: Solar activity has been at low levels for the past 24 hours. The largest solar event of the period was a C5 event observed at 18/2010Z. There is currently 1 numbered sunspot regions on the disk.

IB.  Solar Activity Forecast: Solar activity is expected to be very low with a chance for a C-class flares and a slight chance for an M-class flare on days one, two, and three (19 Apr, 20 Apr, 21 Apr).

IIA.  Geophysical Activity Summary 17/2100Z to 18/2100Z: The geomagnetic field has been at quiet levels for the past 24 hours. Solar wind speed reached a peak of 346 km/s at 18/2055Z. Total IMF reached 8 nT at 18/1948Z. The maximum southward component of Bz reached -5 nT at 18/1809Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 1129 pfu.

IIB.  Geophysical Activity Forecast: The geomagnetic field is expected to be at unsettled to active levels on days one and two (19 Apr, 20 Apr) and quiet to unsettled levels on day three (21 Apr).

III.  Event probabilities 19 Apr-21 Apr
Class M    10/10/10
Class X    01/01/01
Proton     01/01/01
PCAF       green

IV.  Penticton 10.7 cm Flux
Observed           18 Apr 080
Predicted   19 Apr-21 Apr 080/080/080
90 Day Mean        18 Apr 078

V.  Geomagnetic A Indices
Observed Afr/Ap 17 Apr  003/003
Estimated Afr/Ap 18 Apr  011/015
Predicted Afr/Ap 19 Apr-21 Apr  011/015-012/015-007/008

VI.  Geomagnetic Activity Probabilities 19 Apr-21 Apr
A.  Middle Latitudes
Active                40/40/25
Minor Storm           15/15/10
Major-severe storm    01/01/01
B.  High Latitudes
Active                10/10/15
Minor Storm           25/25/25
Major-severe storm    50/50/35