FXXX10 KWNP 191231

DAYTDF



:Product: 3-Day Forecast

: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

# http://www.swpc.noaa.gov/wwire.html

#

#             3-Day Forecast

#

A. NOAA Geomagnetic Activity Observation and Forecast



The greatest observed 3 hr Kp over the past 24 hours was 2 (below NOAA

Scale levels).

The greatest expected 3 hr Kp for Mar 19-Mar 21 2026 is 6.33 (NOAA Scale

G2).



NOAA Kp index breakdown Mar 19-Mar 21 2026



             Mar 19       Mar 20       Mar 21

00-03UT       0.67         6.33 (G2)    4.67 (G1)

03-06UT       0.67         6.00 (G2)    6.33 (G2)

06-09UT       0.67         4.67 (G1)    5.67 (G2)

09-12UT       0.67         4.33         5.33 (G1)

12-15UT       3.33         3.33         4.33     

15-18UT       4.33         3.67         4.67 (G1)

18-21UT       5.33 (G1)    4.00         4.67 (G1)

21-00UT       6.00 (G2)    4.67 (G1)    4.33     



Rationale: G1-G2 (Minor-Moderate) geomagnetic storms are expected over

19-21 Mar due to combined effects of various potential CME arrivals and

a negative polarity CH HSS.



B. NOAA Solar Radiation Activity Observation and Forecast



Solar radiation, as observed by NOAA GOES-18 over the past 24 hours, was

below S-scale storm level thresholds.



Solar Radiation Storm Forecast for Mar 19-Mar 21 2026



              Mar 19  Mar 20  Mar 21

S1 or greater    5%      5%     10%



Rationale: There is a slight chance for S1 (Minor) or greater solar

radiation storms on 21 Mar due to potential accelerated particles ahead

of the anticipated CME arrival.



C. NOAA Radio Blackout Activity and Forecast



No radio blackouts were observed over the past 24 hours.



Radio Blackout Forecast for Mar 19-Mar 21 2026



              Mar 19        Mar 20        Mar 21

R1-R2           35%           35%           35%

R3 or greater    5%            5%            5%



Rationale: There is a chance for R1-R2 (Minor-Moderate) radio blackouts,

with a slight chance for R3 (Strong) events, on 19-21 Mar, primarily due

to the flaring potential of Region 4392.