Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 21 May 2013

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 141 Issued at 2200Z on 21 May 2013

IA. Analysis of Solar Active Regions and Activity from 20/2100Z to
21/2100Z: 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
21/0012Z from Region 1751 (S23W57). There are currently 7 numbered
sunspot regions on the disk.

IB. Solar Activity Forecast: Solar activity is expected to be low with
a chance for M-class flares and a slight chance for an X-class flare on
days one, two, and three (22 May, 23 May, 24 May).

IIA. Geophysical Activity Summary 20/2100Z to 21/2100Z: The geomagnetic
field has been at quiet levels for the past 24 hours. Solar wind speed,
as measured by the ACE spacecraft, reached a peak speed of 570 km/s at
21/1900Z. Total IMF reached 6 nT at 21/1855Z. The maximum southward
component of Bz reached -5 nT at 21/0515Z. Protons greater than 10 MeV
at geosynchronous orbit reached a peak level of 2 pfu at 20/2145Z.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected
to be at quiet to unsettled levels on days one and three (22 May, 24
May) and unsettled to active levels on day two (23 May). Protons have a
slight chance of crossing threshold on days one, two, and three (22 May,
23 May, 24 May).

III. Event probabilities 22 May-24 May
Class M 50/50/50
Class X 20/20/20
Proton 20/20/20
PCAF green

IV. Penticton 10.7 cm Flux
Observed 21 May 125
Predicted 22 May-24 May 120/120/125
90 Day Mean 21 May 121

V. Geomagnetic A Indices
Observed Afr/Ap 20 May 006/008
Estimated Afr/Ap 21 May 007/008
Predicted Afr/Ap 22 May-24 May 011/012-012/015-007/008

VI. Geomagnetic Activity Probabilities 22 May-24 May
A. Middle Latitudes
Active 20/30/15
Minor Storm 05/10/01
Major-severe storm 01/01/01
B. High Latitudes
Active 15/15/15
Minor Storm 25/30/25
Major-severe storm 30/40/20