:Product: 0918RSGA.txt
:Issued: 2023 Sep 18 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 261 Issued at 2200Z on 18 Sep 2023

IA.  Analysis of Solar Active Regions and Activity from 17/2100Z to
18/2100Z: 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
18/1041Z from Region 3435 (N09E56). There are currently 9 numbered
sunspot regions on the disk.
IB.  Solar Activity Forecast: Solar activity is expected to be low with
a slight chance for an M-class flare on days one, two, and three (19
Sep, 20 Sep, 21 Sep).

IIA.  Geophysical Activity Summary 17/2100Z to 18/2100Z: The geomagnetic
field has been at quiet to minor storm levels for the past 24 hours.
Solar wind speed reached a peak of 598 km/s at 18/1617Z. Total IMF
reached 22 nT at 18/1540Z. The maximum southward component of Bz reached
-18 nT at 18/1644Z.  Electrons greater than 2 MeV at geosynchronous
orbit reached a peak level of 734 pfu.
IIB.  Geophysical Activity Forecast: The geomagnetic field is expected
to be at unsettled to major storm levels on day one (19 Sep), quiet to
active levels on day two (20 Sep) and quiet to unsettled levels on day
three (21 Sep).

III.  Event probabilities 19 Sep-21 Sep
Class M    20/20/20
Class X    01/01/01
Proton     05/01/01
PCAF       green

IV.  Penticton 10.7 cm Flux
Observed           18 Sep 155
Predicted   19 Sep-21 Sep 154/154/152
90 Day Mean        18 Sep 162

V.  Geomagnetic A Indices
Observed Afr/Ap 17 Sep  014/020
Estimated Afr/Ap 18 Sep  023/029
Predicted Afr/Ap 19 Sep-21 Sep  022/035-014/015-008/008

VI.  Geomagnetic Activity Probabilities 19 Sep-21 Sep
A.  Middle Latitudes
Active                25/30/20
Minor Storm           40/10/05
Major-severe storm    35/01/01
B.  High Latitudes
Active                05/15/15
Minor Storm           20/20/20
Major-severe storm    75/20/20