Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 27 April 2017

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast

SDF Number 117 Issued at 2200Z on 27 Apr 2017

IA.  Analysis of Solar Active Regions and Activity from 26/2100Z to 27/2100Z: 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 slight chance for a C-class flare on days one, two, and three (28 Apr, 29 Apr, 30 Apr).

IIA.  Geophysical Activity Summary 26/2100Z to 27/2100Z: The geomagnetic field has been at quiet to unsettled levels for the past 24 hours. Solar wind speed reached a peak of 528 km/s at 26/2352Z. Total IMF reached 5 nT at 27/1946Z. The maximum southward component of Bz reached -4 nT at 27/1724Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 54174 pfu.

IIB.  Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to unsettled levels on day one (28 Apr) and quiet levels on days two and three (29 Apr, 30 Apr).

III.  Event probabilities 28 Apr-30 Apr

Class M    01/01/01

Class X    01/01/01

Proton     01/01/01

PCAF       green

IV.  Penticton 10.7 cm Flux

Observed           27 Apr 078

Predicted   28 Apr-30 Apr 079/079/078

90 Day Mean        27 Apr 078

V.  Geomagnetic A Indices

Observed Afr/Ap 26 Apr  008/010

Estimated Afr/Ap 27 Apr  008/008

Predicted Afr/Ap 28 Apr-30 Apr  007/008-005/005-006/005

VI.  Geomagnetic Activity Probabilities 28 Apr-30 Apr

A.  Middle Latitudes

Active                10/05/05

Minor Storm           01/01/01

Major-severe storm    01/01/01

B.  High Latitudes

Active                15/15/15

Minor Storm           25/15/15

Major-severe storm    20/10/05