Routine Space Environment Product (Daily)
Issued by NWS
Issued by NWS
698 FXXX12 KWNP 160036 DAYDIS :Product: Forecast Discussion :Issued: 2026 May 16 0035 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 # # Forecast Discussion # Solar Activity .24 hr Summary... Solar activity was at low levels. Region 4435 (N22W81, Dao/beta) produced the three largest events of the period: a C4.3/Sf at 15/1150 UTC, a C6.7/Sf at 15/1313 UTC, and a C9.5/Sf at 15/1614 UTC. Type II radio sweeps accompanied each flare, with estimated speeds of 486 km/s, 347 km/s, and 529 km/s, respectively. Proper analysis of the magnetic structure of Region 4435 became increasingly difficult as it reached the NW solar limb. Region 4436 (N19W13, Cao/beta) was mostly unchanged and quiet, while Region 4438 (N20W57, Dao/beta) showed continued, yet slower growth during the period. The CMEs mentioned in the previous discussion were deemed to be mostly far-sided or have a trajectory above the ecliptic, and are not expected to impact Earth. .Forecast... Solar activity is expected to remain predominately at low levels, with a chance for M-class (R1-R2/Minor-Moderate) flares through 18 May. Energetic Particle .24 hr Summary... The greater than 2 MeV electron flux was at normal to moderate levels. The greater than 10 MeV proton flux was at background levels. .Forecast... The greater than 2 MeV electron flux is expected to remain at moderate levels through 16 May, likely increasing to high levels on 17-18 May as -CH HSS influences increase. The greater than 10 MeV proton flux is expected to stay at background levels through 18 May. Solar Wind .24 hr Summary... The solar wind parameters reflected increased influence from a negative polarity CH HSS. Total interplanetary magnetic field strength unsteadily increased from around 3 nT to reach as high as 17 nT. The Bz component began the period near neutral before fluctuating between +/-11 nT, seeing a maximum southward deflection to -13 nT. Phi was in a predominantly negative orientation. Wind speeds steadily increased through the period from about 400 km/s to end of the period speeds near 800 km/s. .Forecast... Solar wind parameters are expected to continued to be enhanced through 18 May due to the persistent influence of the negative polarity CH HSS. Geospace .24 hr Summary... The geomagnetic field began the period at quiet levels, followed by an increase to G1 (Minor) and G2 (Moderate), as a CIR and negative polarity CH HSS moved into a geoeffective position. .Forecast... G1 (Minor) and G2 (Moderate) storming conditions are expected to continue on 16 May due to the ongoing effects of a negative polarity CH HSS. Active to G1 (Minor) storm levels are likely to continue on 17 May, decreasing to unsettled to active conditions by 18 May as lingering CH HSS influences diminish.