:Product: Report of Solar-Geophysical Activity
:Issued: 2026 May 19 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 139 Issued at 2200Z on 19 May 2026

IA.  Analysis of Solar Active Regions and Activity from 18/2100Z to
19/2100Z: Solar activity has been at low levels for the past 24 hours.
There are currently 5 numbered sunspot regions on the disk.
IB.  Solar Activity Forecast: Solar activity is likely to be low with a
slight chance for an M-class flare on days one and two (20 May, 21 May)
and expected to be low with a chance for M-class flares on day three (22
May).

IIA.  Geophysical Activity Summary 18/2100Z to 19/2100Z: The geomagnetic
field has been at quiet to active levels for the past 24 hours. Solar
wind speed reached a peak of 655 km/s at 19/0854Z. Total IMF reached 7
nT at 19/1038Z. The maximum southward component of Bz reached -7 nT at
19/0733Z.  Electrons greater than 2 MeV at geosynchronous orbit reached
a peak level of 3917 pfu.
IIB.  Geophysical Activity Forecast: The geomagnetic field is expected
to be at quiet levels on days one and three (20 May, 22 May) and quiet
to unsettled levels on day two (21 May).

III.  Event probabilities 20 May-22 May
Class M    20/20/25
Class X    05/05/05
Proton     05/05/05
PCAF       green

IV.  Penticton 10.7 cm Flux
Observed           19 May 106
Predicted   20 May-22 May 110/110/108
90 Day Mean        19 May 124

V.  Geomagnetic A Indices
Observed Afr/Ap 18 May  008/009
Estimated Afr/Ap 19 May  014/019
Predicted Afr/Ap 20 May-22 May  007/008-007/010-007/009

VI.  Geomagnetic Activity Probabilities 20 May-22 May
A.  Middle Latitudes
Active                15/20/30
Minor Storm           01/05/05
Major-severe storm    01/01/01
B.  High Latitudes
Active                20/20/20
Minor Storm           25/35/35
Major-severe storm    20/25/30