:Product: Report of Solar-Geophysical Activity
:Issued: 2026 May 28 2200 UTC
# Prepared jointly by the U.S. Dept. of Commerce, NOAA,
# Space Weather Prediction Center and the U.S. Air Force.
#
Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 148 Issued at 2200Z on 28 May 2026

IA.  Analysis of Solar Active Regions and Activity from 27/2100Z to
28/2100Z: Solar activity has been at low levels for the past 24 hours.
There are currently 11 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 (29 May, 30 May,
31 May).

IIA.  Geophysical Activity Summary 27/2100Z to 28/2100Z: The geomagnetic
field has been at quiet to active levels for the past 24 hours. Solar
wind speed reached a peak of 491 km/s at 28/2048Z. Total IMF reached 9
nT at 28/1024Z. The maximum southward component of Bz reached -8 nT at
28/0542Z.  Electrons greater than 2 MeV at geosynchronous orbit reached
a peak level of 561 pfu.
IIB.  Geophysical Activity Forecast: The geomagnetic field is expected
to be at quiet to unsettled levels on days one and two (29 May, 30 May)
and quiet to active levels on day three (31 May).

III.  Event probabilities 29 May-31 May
Class M    40/40/40
Class X    05/05/05
Proton     05/05/05
PCAF       green

IV.  Penticton 10.7 cm Flux
Observed           28 May 145
Predicted   29 May-31 May 142/145/142
90 Day Mean        28 May 125

V.  Geomagnetic A Indices
Observed Afr/Ap 27 May  012/011
Estimated Afr/Ap 28 May  010/011
Predicted Afr/Ap 29 May-31 May  011/012-008/010-011/015

VI.  Geomagnetic Activity Probabilities 29 May-31 May
A.  Middle Latitudes
Active                20/15/30
Minor Storm           05/05/10
Major-severe storm    01/01/01
B.  High Latitudes
Active                20/20/20
Minor Storm           25/30/35
Major-severe storm    25/20/35