Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 20 April 2017

Status Report From: Space Weather Prediction Center (NOAA)
Posted: Thursday, April 20, 2017

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 110 Issued at 2200Z on 20 Apr 2017

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 2 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 (21 Apr, 22 Apr, 23 Apr).

IIA.  Geophysical Activity Summary 19/2100Z to 20/2100Z: The geomagnetic field has been at unsettled to major storm levels for the past 24 hours. Solar wind speed reached a peak of 657 km/s at 20/1056Z. Total IMF reached 16 nT at 19/2117Z. The maximum southward component of Bz reached -12 nT at 20/0005Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 546 pfu.

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

III.  Event probabilities 21 Apr-23 Apr
Class M    10/10/10
Class X    01/01/01
Proton     01/01/01
PCAF       green

IV.  Penticton 10.7 cm Flux
Observed           20 Apr 081
Predicted   21 Apr-23 Apr 085/085/085
90 Day Mean        20 Apr 078

V.  Geomagnetic A Indices
Observed Afr/Ap 19 Apr  012/017
Estimated Afr/Ap 20 Apr  024/035
Predicted Afr/Ap 21 Apr-23 Apr  010/012-007/008-028/040

VI.  Geomagnetic Activity Probabilities 21 Apr-23 Apr
A.  Middle Latitudes
Active                30/20/30
Minor Storm           05/05/40
Major-severe storm    01/01/15
B.  High Latitudes
Active                15/20/05
Minor Storm           30/30/20
Major-severe storm    35/25/75

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