Joint USAF/NOAA Solar Geophysical Activity Report and Forecast SDF Number 139 Issued at 2200Z on 19 May 2023

IA. Analysis of Solar Active Regions and Activity from 18/2100Z to 19/2100Z: 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 19/0048Z from Region 3311 (N17E60). There are currently 9 numbered sunspot regions on the disk.

IB. Solar Activity Forecast: Solar activity is likely to be moderate with a chance for X-class flares on days one, two, and three (20 May, 21 May, 22 May).

IIA. Geophysical Activity Summary 18/2100Z to 19/2100Z: The geomagnetic field has been at quiet to unsettled levels for the past 24 hours. Solar wind speed reached a peak of 373 km/s at 19/2059Z. Total IMF reached 12 nT at 19/2100Z. The maximum southward component of Bz reached -8 nT at 19/2038Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 318 pfu.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to active levels on days one and two (20 May, 21 May) and quiet to unsettled levels on day three (22 May). Protons have a slight chance of crossing threshold on days one, two, and three (20 May, 21 May, 22 May).

III. Event probabilities 20 May-22 May
Class M 55/55/55
Class X 25/25/25
Proton 10/10/10
PCAF green

IV. Penticton 10.7 cm Flux
Observed 19 May 165
Predicted 20 May-22 May 165/165/160
90 Day Mean 19 May 153

V. Geomagnetic A Indices
Observed Afr/Ap 18 May 008/004
Estimated Afr/Ap 19 May 005/008
Predicted Afr/Ap 20 May-22 May 009/010-010/012-010/010

VI. Geomagnetic Activity Probabilities 20 May-22 May
A. Middle Latitudes
Active 20/25/35
Minor Storm 05/10/20
Major-severe storm 01/01/05
B. High Latitudes
Active 15/15/20
Minor Storm 30/25/25
Major-severe storm 30/40/30

space weather