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QST de W1AW  
> Propagation Forecast Bulletin 16  ARLP016
> From Tad Cook, K7VVV
> Seattle, WA  April 19, 2002
> To all radio amateurs 
> 
> SB PROP ARL ARLP016
> ARLP016 Propagation de K7VVV
> 
> Average daily sunspot number was up slightly and the average solar
> flux was down a couple of points this week, but the big news was the
> high geomagnetic activity. On Wednesday the planetary A index was
> 41, and K indices over several reporting periods were 6, which is
> very high. The high latitude College A index was 73 and the College
> K index reached 7.
> 
> On April 15 at 0400z a full halo coronal mass ejection blasted away
> from the sun. At 1100z on April 17 energy from that coronal mass
> ejection struck earth's magnetosphere, triggering a geomagnetic
> storm. Several hours earlier another coronal mass ejection left the
> sun, and effects from it may be felt on Friday or Saturday.
> 
> On Thursday the prediction from the U.S. Air Force was for a
> planetary A index of 40 on Friday, 50 on Saturday, and 20 on Sunday.
> It also shows solar flux bottoming-out for the short term around 170
> on Sunday or Monday, then rising above 200 after April 29.
> 
> With a predicted geomagnetic storm this weekend expect particularly
> bad propagation over polar paths, conditions worsening for higher
> latitudes, and some transequatorial propagation, but only because
> that may be the only HF propagation available. Sometimes it is
> assumed that transequatorial propagation (signals crossing the
> equator) is enhanced during geomagnetic storms, but actually these
> signals at times are the only audible ones.
> 
> There was more 6-meter news, this time from W4NTI. From East Central
> Alabama (EM73) he worked Chile and Argentina last Friday evening
> from 0019 to 0052z. This was with only a three-element Yagi at 30
> feet.
> 
> Last week's bulletin presented a problem for users of WA4TTK's solar
> data plotting utility. This program grabs the data in the paragraph
> below and adds it to a database for charting. Unfortunately if you
> look at the second sentence in the first paragraph of last week's
> bulletin, it contains a string of words identical to one found at
> the end of every bulletin. I can't spell it out here, or I would
> cause the same problem all over again. You can get the plotting
> utility to ignore that error if you take out that line. Or you can
> use the ftp function in the program to download the data from ARRL.
> 
> Sunspot numbers for April 11 through 17 were 235, 263, 257, 236,
> 243, 172 and 137 with a mean of 220.4. 10.7 cm flux was 197.4,
> 211.9, 226, 210.3, 203.3, 195.7 and 193.5, with a mean of 205.4, and
> estimated planetary A indices were 13, 13, 14, 13, 7, 10 and 41 with
> a mean of 15.9.
> 


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