Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 21 April 2017

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 111 Issued at 2200Z on 21 Apr 2017

IA.  Analysis of Solar Active Regions and Activity from 20/2100Z to 21/2100Z: Solar activity has been at very low levels for the past 24 hours. There are currently 3 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 on days one, two, and three (22 Apr, 23 Apr, 24 Apr).

IIA.  Geophysical Activity Summary 20/2100Z to 21/2100Z: The geomagnetic field has been at quiet to minor storm levels for the past 24 hours. Solar wind speed reached a peak of 691 km/s at 21/2050Z. Total IMF reached 14 nT at 21/1613Z. The maximum southward component of Bz reached -12 nT at 21/1635Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 2805 pfu.

IIB.  Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to unsettled levels on day one (22 Apr), active to major storm levels on day two (23 Apr) and active to minor storm levels on day three (24 Apr).

III.  Event probabilities 22 Apr-24 Apr
Class M    05/05/05
Class X    01/01/01
Proton     01/01/01
PCAF       green

IV.  Penticton 10.7 cm Flux
Observed           21 Apr 082
Predicted   22 Apr-24 Apr 082/082/082
90 Day Mean        21 Apr 078

V.  Geomagnetic A Indices
Observed Afr/Ap 20 Apr  020/030
Estimated Afr/Ap 21 Apr  012/018
Predicted Afr/Ap 22 Apr-24 Apr  013/015-028/040-023/030

VI.  Geomagnetic Activity Probabilities 22 Apr-24 Apr
A.  Middle Latitudes
Active                40/30/40
Minor Storm           25/40/30
Major-severe storm    05/15/05
B.  High Latitudes
Active                10/05/05
Minor Storm           25/20/20
Major-severe storm    60/75/65