[CQ-Contest] Another Geomagnetic Storm begins

NW7US, Tomas nw7us at hfradio.org
Mon Jul 26 22:44:54 EDT 2004


Since the last NW7US Propagation Bulletin, we have witnessed quite a  
strong geomagnetic storm, with the resulting Auroral propagation even on  
222 MHz.  We usually see storms of this magnitude during the Fall and  
Spring seasons, so this was quite a treat.

Through most of today (26-VII-2004) we have seen the geomagnetic activity  
wane down to a planetary K index (Kp) of 2, after seeing more than a day  
of Kp readings above 5.  A Kp of 8 was reached yesterday.  Now, however,  
we are seeing the Kp rise once again, as the arrival of an additional  
coronal mass ejection is causing geomagnetic disturbance.

At 0218, 27-VII-2004 UTC, we have a solar wind speed of 1015 kilometers  
per hour.  This is an exremely strong solar wind (a typical "quiet" day is  
one where the solar wind speed is somewhere near the 350 km/s range).   
Even with the Bz positive, this intense barrage of solar wind and  
associated coronal mass riding the wind will cause a geomagnetic storm for  
the next 12 hours, at least.  If the Bz turns negative and stays negative  
for any significant length of time (it will fluctuate between north and  
south), we will see a very intense, major geomagnetic storm.

There is a very strong probability for visual aurora in North America,  
tonight.  And, there are already reports of radio aurora on HF and VHF.   
Expect AU on 222 MHz, as well.  This condition will last long enough for  
Asia and Europe to experience yet another day of radio Aurora.

HF and MW will suffer significantly.  Not only because of the geomagnetic  
storm, but because of polar cap absorption.

I am tracking these conditions, as usual, at http://prop.hfradio.org/ -  
and I will post follow-up bulletins as conditions warrent.

Happy Aurora DX!

73 de Tomas, NW7US (AARØJA/AAAØWA)

: Propagation Editor for CQ, CQ VHF, and Popular Communications :
: Quarterly Propagation Columnist for Monitoring Times Magazine :
: Creator of live propagation center - http://prop.hfradio.org/ :
: Member, US Army Miltary Affiliate Radio Service (MARS) AARØJA :
: 122.93W 47.67N / Brinnon, Washington USA - CN87 - CW/SSB/DIGI :
: Website, software, database design - http://newwebmakers.com/ :
: Washington State Army MARS, State Army MARS Director - AAAØWA :
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