[Propagation+Space Weather] Today's Space Weather Forecast Discussion on 2015 Apr 20 1230 UTC

[nw7us@sunspotwatch.com]

This e-mail posting is from the Radio Propagation Reflector that you're 
currently subscribed to.  Refer to the end of this e-mail for directions on how 
to change your subscription options, or to unsubscribe.
_______________________-start-_________________

Here is the current forecast discussion on space weather and geophysical activity, issued 2015 Apr 20 1230 UTC.

Solar Activity

24 hr Summary: Solar activity was low. An unnumbered region behind the northeast limb produced a C1 flare at 20/0052 UTC, which was the largest event of the period. Regions 2321 (N11W43, Eai/beta-gamma), 2324 (N19W11, Cki/beta), and 2325 (N05W02, Dao/beta) were all in decay while the remaining three active regions on the visible disk were stable throughout the period.

Coronal dimming was observed near the southeast limb in SDO/AIA imagery at around 19/1240 UTC followed by a coronal mass ejection (CME) first observed in SOHO/LASCO C2 coronagraph imagery beginning at 19/1325 UTC. This event was associated with solar activity on the far-side of the Sun and not expected to impact Earth. A second CME was observed off the southwest in C2 coronagraph imagery beginning at 19/2124 UTC which was also associated with activity on the far-side. No Earth-directed CMEs were observed this period. Forecast: Solar activity is likely to be low with a slight chance for M-class (R1-Minor) flares over the next three days (20-22 Apr).

Energetic Particle

24 hr Summary: The greater than 2 MeV electron flux was at normal to high levels this period, reaching a peak flux of 6,550 pfu at 19/1600 UTC. The greater than 10 MeV proton flux was at background levels throughout the period.

Forecast: The greater than 2 MeV electron flux is expected to be at normal to moderate levels over the next three days (20-22 Apr) in response to the anticipated onset of a positive polarity coronal hole high speed stream (CH HSS) and the arrival of the 18 Apr CME. The greater than 10 MeV proton flux is expected to persist at background levels over the next three days (20-22 Apr).

Solar Wind

24 hr Summary: Solar wind parameters were indicative of a nominal solar wind regime. Solar wind velocities were steady between 375-425 km/s. IMF total field values were steady between 4-6 nT and Bz reached a maximum southward component of -5 nT late in the period. The phi angle was in a negative (toward the Sun) solar sector orientation throughout the period.

Forecast: Solar wind parameters are expected to become enhanced late on day one (20 Apr) through midday on day two (21 Apr) due to the influence of a positive polarity coronal hole high speed stream (CH HSS). A further enhancement is expected midday on day two due to the anticipated arrival of the 18 Apr CME. Solar wind parameters are expected to begin decreasing midday on day three (22 Apr) as CH HSS and CME effects begin to wane.

Geospace

24 hr Summary: The geomagnetic field was quiet to unsettled under a nominal solar wind environment.

Forecast: The geomagnetic field is expected to be at quiet to unsettled levels for the first half of day one (20 Apr) with unsettled to active conditions likely for the latter half of the day as a positive polarity CH HSS moves into geoeffective position. Unsettled to active field conditions are expected to persist through midday on day two (21 Apr) due to continued CH HSS influence. The anticipated arrival of the 18 Apr CME midday on day two is expected to trigger periods of G1 (Minor) geomagnetic storming through the remainder of day two and into the early hours of day three (22 Apr). Unsettled to active conditions are expected to return after 0900 UTC on day three as CH HSS and CME effects subside.

Don't forget to visit our live space weather and radio propagation web site, at: http://SunSpotWatch.com/

Live Aurora mapping is at http://aurora.sunspotwatch.com/

If you are on Twitter, please follow these two users: + https://Twitter.com/NW7US + https://Twitter.com/hfradiospacewx

Get the space weather and radio propagation self-study course, today. Visit http://nw7us.us/swc for the latest sale and for more information!

We're on Facebook: http://NW7US.us/swhfr

Live data: SunSpotWatch.com

_______________________________________________
Propagation mailing list
Propagation@contesting.com

To change your subscription settings, or to unsubscribe, visit:
http://lists.contesting.com/mailman/listinfo/propagation