Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 18 April 2015

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast

SDF Number 108 Issued at 2200Z on 18 Apr 2015

IA.  Analysis of Solar Active Regions and Activity from 17/2100Z to 18/2100Z: Solar activity has been at low levels for the past 24 hours. The largest solar event of the period was a C5 event observed at 18/1419Z from Region 2321 (N11W22). There are currently 7 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 (19 Apr, 20 Apr, 21 Apr).

IIA.  Geophysical Activity Summary 17/2100Z to 18/2100Z: 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 635 km/s at 17/2305Z. Total IMF reached 5 nT at 18/1255Z. The maximum southward component of Bz reached -4 nT at 18/1349Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 3744 pfu.

IIB.  Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to unsettled levels on day one (19 Apr) and quiet to active levels on days two and three (20 Apr, 21 Apr).

III.  Event probabilities 19 Apr-21 Apr

Class M    20/20/20

Class X    01/01/01

Proton     01/01/01

PCAF       green

IV.  Penticton 10.7 cm Flux

Observed           18 Apr 148

Predicted   19 Apr-21 Apr 150/150/150

90 Day Mean        18 Apr 130

V.  Geomagnetic A Indices

Observed Afr/Ap 17 Apr  020/023

Estimated Afr/Ap 18 Apr  010/012

Predicted Afr/Ap 19 Apr-21 Apr  007/008-010/012-010/012

VI.  Geomagnetic Activity Probabilities 19 Apr-21 Apr

A.  Middle Latitudes

Active                20/30/30

Minor Storm           05/05/05

Major-severe storm    01/01/01

B.  High Latitudes

Active                15/15/15

Minor Storm           30/30/30

Major-severe storm    25/35/35