:Product: Report of Solar-Geophysical Activity
:Issued: 2026 Apr 27 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 117 Issued at 2200Z on 27 Apr 2026

IA.  Analysis of Solar Active Regions and Activity from 26/2100Z to
27/2100Z: Solar activity has been at high levels for the past 24 hours.
There are currently 6 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 (28 Apr, 29
Apr, 30 Apr).

IIA.  Geophysical Activity Summary 26/2100Z to 27/2100Z: The geomagnetic
field has been at quiet to unsettled levels for the past 24 hours. Solar
wind speed reached a peak of 490 km/s at 26/2217Z. Total IMF reached 6
nT at 27/0449Z. The maximum southward component of Bz reached -3 nT at
26/2103Z.  Electrons greater than 2 MeV at geosynchronous orbit reached
a peak level of 373 pfu.
IIB.  Geophysical Activity Forecast: The geomagnetic field is expected
to be at quiet levels on day one (28 Apr) and quiet to active levels on
days two and three (29 Apr, 30 Apr). Protons have a slight chance of
crossing threshold on days one, two, and three (28 Apr, 29 Apr, 30 Apr).

III.  Event probabilities 28 Apr-30 Apr
Class M    70/70/70
Class X    25/25/25
Proton     15/15/15
PCAF       green

IV.  Penticton 10.7 cm Flux
Observed           27 Apr 142
Predicted   28 Apr-30 Apr 145/145/145
90 Day Mean        27 Apr 129

V.  Geomagnetic A Indices
Observed Afr/Ap 26 Apr  013/014
Estimated Afr/Ap 27 Apr  007/007
Predicted Afr/Ap 28 Apr-30 Apr  005/005-009/012-014/014

VI.  Geomagnetic Activity Probabilities 28 Apr-30 Apr
A.  Middle Latitudes
Active                10/20/30
Minor Storm           01/05/10
Major-severe storm    01/01/01
B.  High Latitudes
Active                20/15/15
Minor Storm           20/25/20
Major-severe storm    10/35/20