NOAA / Space Weather Prediction Center

Solar Flare 3-day Report of Solar and Geophysical Activity
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Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Weather Prediction Center and the U.S. Air Force.
Updated 2013 May 24 2200 UTC


Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 144 Issued at 2200Z on 24 May 2013


IA.  Analysis of Solar Active Regions and Activity from 23/2100Z to
24/2100Z: Solar activity has been at low levels for the past 24 hours.
The largest solar event of the period was a C2 event observed at
24/0124Z. There are currently 5 numbered sunspot regions on the disk.

IB.  Solar Activity Forecast: Solar activity is expected to be low with
a chance for M-class flares on days one, two, and three (25 May, 26 May,
27 May).


IIA.  Geophysical Activity Summary 23/2100Z to 24/2100Z: The geomagnetic
field has been at quiet to minor storm levels for the past 24 hours.
Solar wind speed, as measured by the ACE spacecraft, reached a peak
speed of 621 km/s at 24/2058Z. Total IMF reached 15 nT at 24/1739Z. The
maximum southward component of Bz reached -14 nT at 24/1738Z. Protons
greater than 10 MeV at geosynchronous orbit reached a peak level of 368
pfu at 23/2105Z. Electrons greater than 2 MeV at geosynchronous orbit
reached a peak level of 2063 pfu.

IIB.  Geophysical Activity Forecast: The geomagnetic field is expected
to be at quiet to active levels on day one (25 May) and quiet to
unsettled levels on days two and three (26 May, 27 May). Protons are
likely to continue above threshold levels on day one (25 May), have a
chance of remaining above threshold on day two (26 May) and have a
slight chance of remaining above threshold on day three (27 May).


III.  Event probabilities 25 May-27 May
Class M    25/25/25
Class X    01/01/01
Proton     60/30/10
PCAF       yellow


IV.  Penticton 10.7 cm Flux
Observed           24 May 127
Predicted   25 May-27 May 130/125/125
90 Day Mean        24 May 122


V.  Geomagnetic A Indices
Observed Afr/Ap 23 May  008/008
Estimated Afr/Ap 24 May  014/019
Predicted Afr/Ap 25 May-27 May  014/022-008/012-007/008


VI.  Geomagnetic Activity Probabilities 25 May-27 May
A.  Middle Latitudes
Active                35/20/10
Minor Storm           20/05/01
Major-severe storm    05/01/01
B.  High Latitudes
Active                10/15/15
Minor Storm           30/25/20
Major-severe storm    55/25/20