Propagation News – 3 May 2015

| May 1, 2015

What a difference a week makes. Last week we said the solar flux index was predicted to hit the 130s. This week, apart from one tiny spot in the lower western quadrant, the sun is now looking very bare. At the time of writing the solar flux index was 104, and the USAF prediction for the bank holiday week is for an SFI of 100 at the beginning, rising to 135 at the end. The maximum predicted K index is two.

While not stunning, this could bring reasonably settled conditions and some DX on the lower HF bands. Please note that as we have now entered May you should be using the latest smoothed sunspot number of 60 with your VOACAP-based prediction programs. That is down very slightly on last month.

This week we have a reminder to check the bands regardless of what the predictions suggest. Chris, G0DWV worked a string of stations in the USA on 12m on Monday at around 1730UTC, even though the VOACAP Online prediction was quite pessimistic.

And finally, we are now entering the Sporadic-E season so keep an eye on ten metres for openings out to around 1,000-1,500 miles, especially mid-morning, afternoon and early evening.

VHF and up propagation news

Early next week expect flat tropo conditions with large areas of low pressure nearby to the west of Britain and frontal troughs moving into Western Europe. But there are indications of high pressure building again towards the end of the week, and this may produce some enhanced conditions later.

Earlier this week we had Sporadic-E over the Czech Republic, eastern Germany and western Poland, a classic start-of-season cluster, which correlated very well with a southerly jet stream over that part of Europe. There is every reason to hope that the Sporadic-E season has started from our latitudes and with jet streams pushing across the Pyrenees and Alps there is a possibility that these weather ‘triggers’ will be producing the necessary wind shear in the upper atmosphere and hence the chance of some Es.

Check the late morning and late afternoon for 10 and 6m beacons to get to the bands as they open. A lot of ingredients need to be right for Es to happen, so it’s a ‘heads-up’ and not a promise!

Category: GB2RS Propagation News