:Product: 0418RSGA.txt
:Issued: 2025 Apr 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 108 Issued at 2200Z on 18 Apr 2025

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.
There are currently 7 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 (19 Apr, 20 Apr,
21 Apr).

IIA.  Geophysical Activity Summary 17/2100Z to 18/2100Z: The geomagnetic
field has been at quiet to active levels for the past 24 hours. Solar
wind speed reached a peak of 558 km/s at 18/0705Z. Total IMF reached 12
nT at 18/0028Z. The maximum southward component of Bz reached -11 nT at
18/0157Z.  Electrons greater than 2 MeV at geosynchronous orbit reached
a peak level of 313 pfu.
IIB.  Geophysical Activity Forecast: The geomagnetic field is expected
to be at quiet to unsettled levels on days one and two (19 Apr, 20 Apr)
and active to major storm levels on day three (21 Apr).

III.  Event probabilities 19 Apr-21 Apr
Class M    40/40/40
Class X    05/05/05
Proton     01/01/01
PCAF       green

IV.  Penticton 10.7 cm Flux
Observed           18 Apr 156
Predicted   19 Apr-21 Apr 150/150/150
90 Day Mean        18 Apr 175

V.  Geomagnetic A Indices
Observed Afr/Ap 17 Apr  011/011
Estimated Afr/Ap 18 Apr  012/013
Predicted Afr/Ap 19 Apr-21 Apr  008/010-008/008-021/035

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