[Propagation+Space Weather] Today's Space Weather Forecast Discussion on 2015 Sep 21 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 Sep 21 1230 UTC.

Solar Activity

24 hr Summary: Solar activity was as moderate levels. Region 2415 (S18W62, Eao/beta-gamma) produced the largest flare of the period, an M2/2n flare at 20/1803 UTC. Associated with the flare were a Type II radio sweep (1304 km/s), a 320 sfu Tenflare, and a coronal mass ejection (CME) first observed off the SW limb in SOHO/LASCO C2 imagery at 20/1824 UTC. This CME is a combination of a slower CME to the north (appears to be a limb event in SDO/AIA 171 imagery) with the much faster (est. speed 825 km/s) CME associated with the M2 flare just to its south. WSA/ENLIL modeling of the event showed the bulk of the ejecta to the SW of the Sun-Earth line. However, a rise in the lower energy protons in the ACE/EPAM instrument suggests a possible shock enhancement by late on 22 Sep to early on 23 Sep.

Other activity included a C8/Sn flare at 21/0518 UTC from Region 2420 (N10E71, Ekc/beta-gamma) with an associated 140 sfu Tenflare and a non Earth-directed CME.

Slight decay was observed in the smaller intermediate and trailing spots in Region 2415. Slight growth was observed in the leader and trailing spots of Region 2420.

Forecast: Solar activity is expected to be at low levels with a chance for M-class (R1-R2, Minor-Moderate) flares over the forecast period (21-23 Sep). The most likely regions to produce M-class activity are Regions 2415 and 2420.

Energetic Particle

24 hr Summary: The greater than 2 MeV electron flux ranged from normal to moderate levels with a peak flux of 383 pfu at 20/1750 UTC. The greater than 10 MeV proton flux saw a minor enhancement (below S1-Minor) associated with the 20/1803 UTC flare that peaked at 3 pfu at 20/2045 UTC.

Forecast: The greater than 2 MeV electron flux at geosynchronous orbit is expected to be at normal to moderate levels on day one (21 Sep) with high levels possible on days two and three (22-23 Sep) due to a combination of coronal hole high speed stream (CH HSS) and CME influences. There is a slight chance for the greater than 10 MeV proton flux to reach S1 (Minor) levels for days one and two (21-22 Sep). As Region 2415 rotates off the limb on day three (23 Sep), the slight chance for S1 (Minor) conditions will decrease.

Solar Wind

24 hr Summary: Solar wind parameters indicated residual CME activity transitioning into a positive polarity CH HSS. Solar wind speed was variable between 442 km/s to 660 km/s with total field ranging from 4 nT to 10 nT. The Bz component was mostly southward early in the period near -6 nT, but became variable between -4 nT and +7 nT by mid period. Phi angle was oriented in a predominantly positive (away) sector.

Forecast: Solar wind conditions are expected to continue to be enhanced under CH HSS influence for day one (21 Sep). As day two (22 Sep) approaches, solar winds are expected to slowly decline towards background levels. There is a possibility of a shock enhancement by late on 22 Sep through early on 23 Sep from the 20 Sep CME.

Geospace

24 hr Summary: The geomagnetic field was at quiet to minor storm (G1-Minor) levels due to residual CME effects followed by CH HSS activity. Minor storming was observed during the 20/1500-1800 period.

Forecast: The geomagnetic field is expected to be at quiet to active levels for the forecast period (21-23 Sep) due to CH HSS effects and a possible shock enhancement late on 22 Sep to early on 23 Sep from the 20 Sep CME.

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!

Check out the stunning view of our Sun in action, as seen during the last five years with the Solar Dynamics Observatory (SDO): https://www.youtube.com/watch?v=zXN-MdoGM9g

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