:Product: 0521RSGA.txt
:Issued: 2023 May 21 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 141 Issued at 2200Z on 21 May 2023

IA.  Analysis of Solar Active Regions and Activity from 20/2100Z to
21/2100Z: Solar activity has been at high levels for the past 24 hours.
The largest solar event of the period was a M5 event observed at
20/2306Z from Region 3311 (N18E47). There are currently 8 numbered
sunspot regions on the disk.
IB.  Solar Activity Forecast: Solar activity is expected to be moderate
with a chance for X-class flares on days one, two, and three (22 May, 23
May, 24 May).

IIA.  Geophysical Activity Summary 20/2100Z to 21/2100Z: The geomagnetic
field has been at quiet to major storm levels for the past 24 hours.
Solar wind speed reached a peak of 632 km/s at 20/2216Z. Total IMF
reached 13 nT at 21/1516Z. The maximum southward component of Bz reached
-10 nT at 21/1935Z.  Electrons greater than 2 MeV at geosynchronous
orbit reached a peak level of 1084 pfu.
IIB.  Geophysical Activity Forecast: The geomagnetic field is expected
to be at quiet to major storm levels on day one (22 May), quiet to minor
storm levels on day two (23 May) and unsettled to minor storm levels on
day three (24 May). Protons have a slight chance of crossing threshold
on days one, two, and three (22 May, 23 May, 24 May).

III.  Event probabilities 22 May-24 May
Class M    75/75/75
Class X    30/30/30
Proton     15/15/15
PCAF       green

IV.  Penticton 10.7 cm Flux
Observed           21 May 163
Predicted   22 May-24 May 160/155/150
90 Day Mean        21 May 153

V.  Geomagnetic A Indices
Observed Afr/Ap 20 May  026/030
Estimated Afr/Ap 21 May  013/021
Predicted Afr/Ap 22 May-24 May  016/022-014/018-020/022

VI.  Geomagnetic Activity Probabilities 22 May-24 May
A.  Middle Latitudes
Active                35/35/35
Minor Storm           35/20/30
Major-severe storm    20/05/15
B.  High Latitudes
Active                10/15/15
Minor Storm           25/20/25
Major-severe storm    60/20/50