Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 20 April 2015

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast

SDF Number 110 Issued at 2200Z on 20 Apr 2015

IA.  Analysis of Solar Active Regions and Activity from 19/2100Z to 20/2100Z: Solar activity has been at low levels for the past 24 hours. The largest solar event of the period was a C1 event observed at 20/1954Z. 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 (21 Apr, 22 Apr, 23 Apr).

IIA.  Geophysical Activity Summary 19/2100Z to 20/2100Z: The geomagnetic field has been at quiet to unsettled levels for the past 24 hours. Solar wind speed, as measured by the ACE spacecraft, reached a peak speed of 437 km/s at 20/2100Z. Total IMF reached 13 nT at 20/2042Z. The maximum southward component of Bz reached -5 nT at 20/0850Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 2619 pfu.

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

III.  Event probabilities 21 Apr-23 Apr

Class M    15/15/15

Class X    01/01/01

Proton     01/01/01

PCAF       green

IV.  Penticton 10.7 cm Flux

Observed           20 Apr 150

Predicted   21 Apr-23 Apr 150/155/155

90 Day Mean        20 Apr 130

V.  Geomagnetic A Indices

Observed Afr/Ap 19 Apr  009/009

Estimated Afr/Ap 20 Apr  010/012

Predicted Afr/Ap 21 Apr-23 Apr  024/035-022/027-011/012

VI.  Geomagnetic Activity Probabilities 21 Apr-23 Apr

A.  Middle Latitudes

Active                45/45/30

Minor Storm           35/25/05

Major-severe storm    10/05/01

B.  High Latitudes

Active                05/05/15

Minor Storm           20/20/30

Major-severe storm    75/65/35