:Product: 0917RSGA.txt
:Issued: 2026 Sep 17 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 260 Issued at 2200Z on 17 Sep 2026

IA.  Analysis of Solar Active Regions and Activity from 16/2100Z to
17/2100Z: Solar activity has been at very low levels for the past 24
hours. There are currently 1 numbered sunspot regions on the disk.
IB.  Solar Activity Forecast: Solar activity is expected to be very low
with a chance for a C-class flares on days one, two, and three (18 Sep,
19 Sep, 20 Sep).

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 reached a peak of 567 km/s at 17/0231 UTC. Total IMF reached
7 nT at 17/0148 UTC. The maximum southward component of Bz reached -4 nT
at 17/0247 UTC.  Electrons greater than 2 MeV at geosynchronous orbit
reached a peak level of 584 pfu.
IIB.  Geophysical Activity Forecast: The geomagnetic field is expected
to be at quiet to active levels on day one (18 Sep), quiet to unsettled
levels on day two (19 Sep) and quiet levels on day three (20 Sep).

III.  Event probabilities 18 Sep-20 Sep
Class M    05/05/05
Class X    01/01/01
Proton     01/01/01
PCAF       green

IV.  Penticton 10.7 cm Flux
Observed           17 Sep 097
Predicted   18 Sep-20 Sep 095/090/090
90 Day Mean        17 Sep 126

V.  Geomagnetic A Indices
Observed Afr/Ap 16 Sep  007/009
Estimated Afr/Ap 17 Sep  014/016
Predicted Afr/Ap 18 Sep-20 Sep  010/012-007/008-007/008

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