[Propagation] NW7US Propagation Update Bulletin 16-I-2005 0430 UTC

["NW7US, Tomas" <nw7us@hfradio.org>]

NW7US Propagation Update Bulletin 16-I-2005 0430 UTC

At the time of this bulletin, we've just witnessed another long-duration  
flare.  This is the strongest of the flares so far unleashed by active  
sunspot region 720 (NOAA 10720).  This flare was a major X2.6-class event  
that peaked at 2302 UTC 15-I-2005.  A Type II radio burst was detected,  
and a proton event is currently underway, as well.

A very fast coronal mass ejection was associated with this X2.6 flare.  It  
looks like the majority of the plasma mass will just miss the Earth, yet  
we expect at least a glancing blow.  We expect this to occur sometime on  
17 or 18 January 2005, riding on the heels of the CME from the M-class  
long-duration flare from earlier (refer to my last bulletin).  This will  
cause the geomagnetic storm to be prolonged.  The storm will begin at any  
time in the next 24 hours, and last well past 17 January 2005.  We expect  
minor storm levels on 16 January, severe storm levels on 17 and 18 January.

The solar activity has significantly risen as a result of the active solar  
regions.  The 10.7-cm Flux has reach 145, and is expected to increase to  
perhaps 150 by 17 and 18 January 2005.  This has opened up paths on  
frequencies as high as 10 meters.

This translates to disrupted HF conditions caused by shortwave fadeouts  
for the next three days due to active solar region 720 (and possibly from  
flares from 718).  When the CME clouds arrive and impact our environment  
we expect the Maximum Usable Frequencies on most signal paths to become  
very depressed in coming days.  HF communication may become very difficult  
if this active solar region continues to flare, while at the same time we  
have the storm conditions in the geomagnetic field around the Earth.

Look for active visual Aurora starting tonight and through the next few  
days (even in mid- to low-latitude regions).  Energetic pulses will  
occur.  Aurora-E / Aurora-mode propagation is likely.

Active region 720 unleashed a total of 20 flares during 15 January 2005.   
These are:

Event Begin/Max/End  Level Reg#
-------------------------------
2690 + 0022 0043 0102 X1.2 0720
2740 + 0234 0239 0244 C2.9 0720
2750 + 0316 0340 0357 C4.2 0720
2760 + 0409 0416 0422 M1.3 0720
2770 + 0426 0431 0436 M8.4 0720
2780 + 0554 0638 0717 M8.6 0720
2820 + 1141 1148 1150 M1.2 0720
2830 + 1227 1231 1234 C7.4 0720
2890 + 1352 1357 1359 C5.5 0720
2900 + 1408 1423 1439 M3.2 0718
2940 + 1650 1657 1702 C8.0 0720
3000 + 1703 1707 1709 C7.2 0720
2960 + 1749 1816 1824 C4.2 0720
3010   1757 1802 1805 C2.9 0720
2970   1812 1815 1818 C4.4 ?
3020 + 1842 1853 1901 C8.8 0720
3040 + 1944 1949 1954 C3.5 0720
3050 + 2008 2022 2027 C5.4 0720
3080 + 2201 2208 2216 M1.0 0720
3090 + 2225 2302 2331 X2.6 0720

Updates will be posted if and when warrented.


73 de Tomas, NW7US (AAR0JA/AAA0WA)

: Propagation Editor for CQ, CQ VHF, Popular Communications :
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