Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 23 April 2015

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast

SDF Number 113 Issued at 2200Z on 23 Apr 2015

IA.  Analysis of Solar Active Regions and Activity from 22/2100Z to

23/2100Z: Solar activity has been at moderate levels for the past 24

hours. The largest solar event of the period was a M1 event observed at

23/1007Z from Region 2322 (just beyond west limb). There are currently 8

numbered sunspot regions on the disk.

IB.  Solar Activity Forecast: Solar activity is expected to be low with

a slight chance for an M-class flare on days one, two, and three (24

Apr, 25 Apr, 26 Apr).

IIA.  Geophysical Activity Summary 22/2100Z to 23/2100Z: The geomagnetic

field has been at quiet to active levels for the past 24 hours. Solar

wind speed, as measured by the ACE spacecraft, reached a peak speed of

555 km/s at 22/2319Z. Total IMF reached 6 nT at 22/2210Z. The maximum

southward component of Bz reached -4 nT at 22/2138Z. Electrons greater

than 2 MeV at geosynchronous orbit reached a peak level of 955 pfu.

IIB.  Geophysical Activity Forecast: The geomagnetic field is expected

to be predominantly quiet to unsettled for the next three days (24-26

Apr).

III.  Event probabilities 24 Apr-26 Apr

Class M    20/20/20

Class X    01/01/01

Proton     01/01/01

PCAF       green

IV.  Penticton 10.7 cm Flux

Observed           23 Apr 141

Predicted   24 Apr-26 Apr 135/130/125

90 Day Mean        23 Apr 131

V.  Geomagnetic A Indices

Observed Afr/Ap 22 Apr  009/011

Estimated Afr/Ap 23 Apr  009/010

Predicted Afr/Ap 24 Apr-26 Apr  007/008-009/012-007/008

VI.  Geomagnetic Activity Probabilities 24 Apr-26 Apr

A.  Middle Latitudes

Active                15/25/15

Minor Storm           05/05/05

Major-severe storm    01/01/01

B.  High Latitudes

Active                15/20/15

Minor Storm           25/30/25

Major-severe storm    20/30/20