FXXX12 KWNP 191231

DAYDIS



:Product: Forecast Discussion

:Issued: 2026 Mar 19 1230 UTC

# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center

# Product description and SWPC contact on the Web

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#             Forecast Discussion

#

Solar Activity



.24 hr Summary...

Solar activity was at low levels, with the largest flare of the period

being a C3.6 at 18/1311 UTC from Region 4392 (S17W26, Csi/beta-gamma).

This region has shown sporadic growth and reorganization in the

peripheral spots over the week, but looks to slowly consolidating and

canceling magnetic flux. Regions 4391 (N07, L=66) and 4395 (S06, L=6)

fully decayed to plage. The remaining regions are either in slight decay

or stable.



No Earth-directed CMEs were observed in available coronagraph imagery.



.Forecast...

Solar activity is expected to be low, with a chance for M-class (R1-R2;

Minor-Moderate) level events 19-21 Mar due primarily to the minor

instability and variability of Region 4392.





Energetic Particle



.24 hr Summary...

The greater than 2 MeV electron flux reached high levels, with a

peak of 2,949 pfu at 18/1715 UTC. The greater than 10 MeV proton flux

continued at background levels.



.Forecast...

The greater than 2 MeV electron flux is likely to have a brief return to

normal-moderate levels on late 19 Mar and 20 Mar, due to CME arrival,

returning to high levels on 21 Mar. The greater than 10 MeV proton flux

is expected to continue at background values, with a slight chance for

an S1 (Minor) level event 19-21 Mar due to possible CME shock

enhancement influences.





Solar Wind



.24 hr Summary...

Solar wind parameters reflected near background conditions, with a very

coherent magnetic structure appearing after 18/2315 UTC. Total IMF

strength averaged near 4 nT. The Bz component was predominantly

northward, and solar wind speed gradually decreased from 400 km/s to end

the period around 350 km/s. The phi angle was predominantly positive.



.Forecast...

The solar wind environment is expected to become enhanced on 19 Mar as

the 16-17 Mar CMEs are expected to arrive. The disturbed solar

environment is likely to continue as CME passage persists into 20 Mar.

By 21 Mar, the CME from 18 Mar is expected to arrive in conjunction with

the onset of a negative polarity CH HSS.





Geospace



.24 hr Summary...

The geomagnetic field was quiet.



.Forecast...

The geomagnetic field is expected to become enhanced on 19-21 Mar as

multiple CMEs and a negative polarity CH HSS impact Earth. Active to G2

(Moderate) storm levels are likely on 19-20 Mar as CMEs from 16-17 Mar

are anticipated to arrive. Additional G2 (Moderate) storm conditions are

likely, with G3 (Strong) conditions possible, on 21 Mar as the CME from

18 Mar is expected to arrive in conjunction with the onset of a negative

polarity CH HSS.