Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 21 April 2015

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast

SDF Number 111 Issued at 2200Z on 21 Apr 2015

IA.  Analysis of Solar Active Regions and Activity from 20/2100Z to 21/2100Z: Solar activity has been at high levels for the past 24 hours. The largest solar event of the period was a M4 event observed at 21/1545Z from Region 2322 (N11W87). There are currently 9 numbered sunspot regions on the disk.

IB.  Solar Activity Forecast: Solar activity is expected to be low with a chance for M-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 unsettled to active levels for the past 24 hours. Solar wind speed, as measured by the ACE spacecraft, reached a peak speed of 628 km/s at 21/0632Z. Total IMF reached 14 nT at 20/2127Z. The maximum southward component of Bz reached -7 nT at 21/0249Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 1433 pfu.

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

III.  Event probabilities 22 Apr-24 Apr

Class M    30/30/30

Class X    05/05/05

Proton     05/05/05

PCAF       green

IV.  Penticton 10.7 cm Flux

Observed           21 Apr 154

Predicted   22 Apr-24 Apr 155/160/160

90 Day Mean        21 Apr 130

V.  Geomagnetic A Indices

Observed Afr/Ap 20 Apr  009/011

Estimated Afr/Ap 21 Apr  020/031

Predicted Afr/Ap 22 Apr-24 Apr  019/025-015/015-007/008

VI.  Geomagnetic Activity Probabilities 22 Apr-24 Apr

A.  Middle Latitudes

Active                45/30/20

Minor Storm           25/05/05

Major-severe storm    05/01/01

B.  High Latitudes

Active                05/15/15

Minor Storm           20/30/25

Major-severe storm    65/35/25