Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 20 April 2018

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 110 Issued at 2200Z on 20 Apr 2018

IA.  Analysis of Solar Active Regions and Activity from 19/2100Z to 20/2100Z: Solar activity has been at very low levels for the past 24 hours. There are currently 1 numbered sunspot regions on the disk.

IB.  Solar Activity Forecast: Solar activity is expected to be very low with a slight chance for a C-class flare on days one, two, and three (21 Apr, 22 Apr, 23 Apr).

IIA.  Geophysical Activity Summary 19/2100Z to 20/2100Z: The geomagnetic field has been at quiet to major storm levels for the past 24 hours. Solar wind speed reached a peak of 637 km/s at 20/1932Z. Total IMF reached 23 nT at 20/0517Z. The maximum southward component of Bz reached -19 nT at 20/0812Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 2168 pfu.

IIB.  Geophysical Activity Forecast: The geomagnetic field is expected to be at unsettled to minor storm levels on day one (21 Apr), quiet to unsettled levels on day two (22 Apr) and quiet levels on day three (23 Apr).

III.  Event probabilities 21 Apr-23 Apr
Class M    01/01/01
Class X    01/01/01
Proton     01/01/01
PCAF       green

IV.  Penticton 10.7 cm Flux
Observed           20 Apr 073
Predicted   21 Apr-23 Apr 075/075/075
90 Day Mean        20 Apr 070

V.  Geomagnetic A Indices
Observed Afr/Ap 19 Apr  002/002
Estimated Afr/Ap 20 Apr  029/048
Predicted Afr/Ap 21 Apr-23 Apr  019/025-010/010-005/005

VI.  Geomagnetic Activity Probabilities 21 Apr-23 Apr
A.  Middle Latitudes
Active                35/30/10
Minor Storm           25/10/01
Major-severe storm    10/01/01
B.  High Latitudes
Active                10/20/20
Minor Storm           25/30/20
Major-severe storm    55/35/10