Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 17 May 2013

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 137 Issued at 2200Z on 17 May 2013


IA.  Analysis of Solar Active Regions and Activity from 16/2100Z to
17/2100Z: Solar activity has been at moderate levels for the past 24
hours. The largest solar event of the period was a M3 event observed at
17/0857Z from Region 1748 (N12E23). There are currently 10 numbered
sunspot regions on the disk.

IB.  Solar Activity Forecast: Solar activity is expected to be at
moderate to high levels with a chance for X-class flares on days one,
two, and three (18 May, 19 May, 20 May).


IIA.  Geophysical Activity Summary 16/2100Z to 17/2100Z: 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
431 km/s at 17/0120Z. Total IMF reached 7 nT at 17/1927Z. The maximum
southward component of Bz reached -5 nT at 16/2126Z. Protons greater
than 10 MeV at geosynchronous orbit reached a peak level of 41 pfu at
17/1720Z. Electrons greater than 2 MeV at geosynchronous orbit reached a
peak level of 203 pfu.

IIB.  Geophysical Activity Forecast: The geomagnetic field is expected
to be at quiet to unsettled levels on day one (18 May), quiet to major
storm levels on day two (19 May) and quiet to active levels on day three
(20 May). Protons are expected to continue above threshold levels on
days 1-3 (18-20 May).


III.  Event probabilities 18 May-20 May
Class M    75/75/75
Class X    50/50/50
Proton     99/95/90
PCAF       red


IV.  Penticton 10.7 cm Flux
Observed           17 May 136
Predicted   18 May-20 May 140/140/135
90 Day Mean        17 May 120


V.  Geomagnetic A Indices
Observed Afr/Ap 16 May  012/015
Estimated Afr/Ap 17 May  010/012
Predicted Afr/Ap 18 May-20 May  008/008-017/034-012/016


VI.  Geomagnetic Activity Probabilities 18 May-20 May
A.  Middle Latitudes
Active                15/35/30
Minor Storm           05/30/10
Major-severe storm    01/20/01
B.  High Latitudes
Active                15/05/15
Minor Storm           25/20/30
Major-severe storm    25/75/40