Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 27 May 2021

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 147 Issued at 2200Z on 27 May 2021

IA.  Analysis of Solar Active Regions and Activity from 26/2100Z to 27/2100Z: Solar activity has been at low levels for the past 24 hours. The largest solar event of the period was a C3 event observed at 26/2124Z from Region 2826 (N24W60). There are currently 2 numbered sunspot regions on the disk.

IB.  Solar Activity Forecast: Solar activity is expected to be very low with a chance for a C-class flares and a slight chance for an M-class flare on days one and two (28 May, 29 May) and expected to be very low with a slight chance for a C-class flare on day three (30 May).

IIA.  Geophysical Activity Summary 26/2100Z to 27/2100Z: The geomagnetic field has been at quiet to active levels for the past 24 hours. Solar
wind speed reached a peak of 448 km/s at 27/2035Z. Total IMF reached 16 nT at 27/0254Z. The maximum southward component of Bz reached -11 nT at
27/0518Z.  Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 187 pfu.

IIB.  Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to unsettled levels on day one (28 May) and quiet levels on days two and three (29 May, 30 May).

III.  Event probabilities 28 May-30 May
Class M    10/10/01
Class X    01/01/01
Proton     01/01/01
PCAF       green

IV.  Penticton 10.7 cm Flux
Observed           27 May 083
Predicted   28 May-30 May 083/081/080
90 Day Mean        27 May 077

V.  Geomagnetic A Indices
Observed Afr/Ap 26 May  012/014
Estimated Afr/Ap 27 May  017/021
Predicted Afr/Ap 28 May-30 May  008/010-005/005-007/008

VI.  Geomagnetic Activity Probabilities 28 May-30 May
A.  Middle Latitudes
Active                20/10/15
Minor Storm           05/01/05
Major-severe storm    01/01/01

B.  High Latitudes
Active                15/15/15
Minor Storm           30/20/25
Major-severe storm    30/10/25