Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 20 May 2013

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 140 Issued at 2200Z on 20 May 2013

IA. Analysis of Solar Active Regions and Activity from 19/2100Z to
20/2100Z: Solar activity has been at moderate levels for the past 24
hours. The largest solar event of the period was a M1 event observed at
20/0525Z. There are currently 7 numbered sunspot regions on the disk.

IB. Solar Activity Forecast: Solar activity is likely to be moderate
with a chance for X-class flares on days one, two, and three (21 May, 22
May, 23 May).

IIA. Geophysical Activity Summary 19/2100Z to 20/2100Z: The geomagnetic
field has been at quiet to active levels for the past 24 hours. Solar
wind speed, as measured by the ACE spacecraft, reached a peak speed of
493 km/s at 19/2257Z. Total IMF reached 14 nT at 19/2256Z. The maximum
southward component of Bz reached -5 nT at 20/1953Z. Protons greater
than 10 MeV at geosynchronous orbit reached a peak level of 4 pfu at
19/2255Z.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected
to be at quiet to unsettled levels on days one and two (21 May, 22 May)
and unsettled to active levels on day three (23 May). Protons have a
chance of crossing threshold on days one, two, and three (21 May, 22
May, 23 May).

III. Event probabilities 21 May-23 May
Class M 65/65/65
Class X 25/25/25
Proton 25/25/25
PCAF green

IV. Penticton 10.7 cm Flux
Observed 20 May 132
Predicted 21 May-23 May 130/125/125
90 Day Mean 20 May 121

V. Geomagnetic A Indices
Observed Afr/Ap 19 May 011/014
Estimated Afr/Ap 20 May 006/006
Predicted Afr/Ap 21 May-23 May 007/008-011/012-012/015

VI. Geomagnetic Activity Probabilities 21 May-23 May
A. Middle Latitudes
Active 15/20/30
Minor Storm 01/05/10
Major-severe storm 01/01/01
B. High Latitudes
Active 15/15/15
Minor Storm 25/25/30
Major-severe storm 20/30/40