[HCDX] Propagation Forecast - update for CQ WW SSB weekend

[Tomas (NW7US) <nw7us@xxxxxxxxxxx>]

While it is currently very hard to predict what will happen in the next few days 
because of the complex and surprising rise in solar activity, I'd like to 
venture a possible outlook for this weekend's contest.  Those of you who will 
try to SWL contest stations are in for possibly great DX.

NOAA SEC currently is forecasting space weather for the next 24 hours (which  
covers the very first part of the contest period) to be minor.  Minor  
Geomagnetic storms are expected, as well as possible minor radio blackouts.   
SIDC is predicting possible proton events, and somewhat agrees with NOAA  
forecasts, except that the geomagnetic activity level might be major storm 
levels.

Right now, the Interplanetary Magnetic Flux is mostly oriented toward the north.  
When this is oriented south (Bz is negative), then it will affect the  
geomagnetic field.  But, if north (Bz is positive), then it will not affect the  
geomagnetic field.

Several CMEs have been observed, one which will arrive sometime during UTC 24  
October 2003.  When this CME glances the Earth's magnetosphere, the IMF has to  
be south (Bz negative) if it were to cause a geomagnetic storm.  The thinking at  
this time is that the Bz will not go negative, or if it will, it will not go  
very far.  Thus, the geomagnetic activity level should not go too high, at most  
it will be at minor storm levels during the late afternoon and early evening of  
the 24th.

By the way, the large sunspots currently in the news is not directly the cause  
of geomagnetic storms.  The IMF and solar wind speed, along with enhancements  
from CMEs, cause geomagnetic storminess.  If the sunspot group throws a flare,  
however, we might have a short radio blackout.  SIDC predicts a 50% or greater  
chance of a moderate to major flare which could cause radio blackouts during the  
contest period.

So, what is in store for the contest (CQ WW SSB) weekend, starting tomorrow?

Solar activity is drastically higher than just a week ago. Now, we have two very  
large sunspot groups. Things look great, in terms of the flux levels expected.   
Solar flux levels will reach as high as 170 to 190 during the contest period.

On the other hand, we expect flares, possible CME-caused geomagnetic storminess,  
and proton events, that will cause a degradation of HF propagation.  

I predict that the start of the contest (at 0000Z on 24 October, 2003, which is  
evening time for most of the USA) will be somewhat rough - polar paths and paths  
over high latitudes will be degraded more than mid-latitude paths. Higher bands  
will shut down quickly.  Low bands should be fair.  

The full day of Saturday will fare better.  Low bands will improve, and, perhaps  
because of the lower Ap and expected Kp after the CME impact on the 24th, along  
with stronger Flux expected on the 25th, we'll see great conditions as high as  
15 meters.  Ten meters might still show promise, as well, so check it out.   
While the geomagnetic field will be active for the remainder of the period, it  
will be decreasing.  That will make the lower bands hot for the remainder of the  
contest period.

Think of it: A flux of 150 to possibly as high as 200 will open up propagation  
even on the highest bands (could we see some six meter activity?).  That will  
open up the higher bands and will also open up many paths around the world  
throughout the day and possibly during the night, on 40 through 15.  Geomagnetic  
activity will degrade the strength and duration of the openings on the highest  
bands, but not they will not be as closed as they could have been if the flux  
was at or slightly below 100, as it has been lately.  Again, I think that the  
combined high flux and the moderately active geomagnetic field will balance out  
for good to possibly excellent conditions depending on the band and time of day, 
and so forth.

Of course, it is possible that the sun will surprise us, with massive flares and  
that the Bz will turn sharply and strongly south.  If that were to happen, spend  
time with family and friends.  :)  Bottomline: don't give up.  Give it a try.  
There might be some very pleasant surprises in store.

73 de Tomas, NW7US (AAR0JA/AAM0EWA)
--
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