[RSM] W3LPL: condx continue thru Thurs/19
Art Boyars
artboyars at gmail.com
Wed Aug 18 01:01:24 EDT 2021
Formatted text still rejected.
From: donovanf at erols.com
To: PVRC Submissions <pvrc at mailman.qth.net>
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Date: Wed, 18 Aug 2021 00:46:32 -0400 (EDT)
Subject: [PVRC] Normal but near solar minimum propagation is likely to
continue through Thursday August 19th
My propagation forecast derived from today's NOAA/SWPC
web pages is published five days a week (M-F) in the Daily DX.
Propagation crossing low and mid latitudes, the auroral ovals and
polar regions is likely to be normal but near solar minimum
conditions through Thursday.
Click here for today’s latest planetary Kp Index, updated every three hours.
Click here for N0NBH’s current HF Band Conditions, updated regularly.
We are transitioning into more frequent mildly active geomagnetic
activity through late August. The more geomagnetically active
autumn equinox season begins in September and runs through
late October.
Sporadic-E propagation will be shorter in duration and more
unreliable at mid-latitudes in the northern hemisphere through
late August making long distance propagation up to about 8,000 km
intermittent and unreliable in the 17, 15, 12 and 10 meter bands
from a few hours after sunrise until a few hours after sunset.
The solar flux index (SFI) is likely to be 73 or less through Thursday.
The sun’s visible disk has one small active region with three tiny
decaying sunspots having no effect on propagation.
https://sdo.gsfc.nasa.gov/assets/img/latest/latest_1024_0171.jpg
160 and 80 meter propagation from North America to VK/ZL and
the south Pacific is likely to be normal through Thursday. 40 meter
short path propagation to south Asia at about 0015Z is likely to be
normal through Thursday. 40 meter short path propagation from
North America to east Asia after about 0930Z is likely to be normal
through Thursday.
30 meter propagation through the auroral ovals and polar regions
is likely to be normal through Thursday. 30 meter propagation is
always significantly degraded within a few hours of local noon
because of E-region blanketing of long distance F2 propagation.
30 meter night time long distance propagation in the northern
hemisphere is likely to less reliable due to decreased ionizing
solar radiation in the northern high latitude regions caused by
lower solar elevation angles and lengthening nights with no source
of ionizing solar radiation.
20 meter daytime and evening propagation through the auroral ovals
and polar regions is likely to be normal through Thursday. 20 meter
northern transpolar propagation within a few hours of sunrise and
sunset is less reliable and shorter in duration due to decreased ionizing
solar radiation in the northern high latitude regions caused by lower
solar elevation angles and lengthening nights with no source of
ionizing solar radiation. 20 meter long distance propagation is
significantly degraded from mid-morning through late afternoon
at mid and especially low latitudes in the northern hemisphere by
F1 region mid-day blanketing of low angle long distance propagation
through late August. 20 meter late afternoon, nighttime and early
morning long distance propagation in the northern hemisphere is
likely to be significantly shorter in duration due to decreased ionizing
solar radiation in the northern high latitude regions caused by
declining elevation angles and lengthening nights with no source
of ionizing solar radiation.
17 and 15 meter daytime long distance propagation in the northern
hemisphere is likely to be shorter in duration due to decreased
ionizing solar radiation in the northern high latitude regions caused
by lower solar elevation angles and lengthening nights with
no source of ionizing solar radiation. 17, 15, 12 and 10 meter
sporadic-E propagation up to 8,000 km is likely to be intermittent,
short duration and unreliable from a few hours after sunrise until
a few hours after sunset through late August.
Geomagnetic disturbances caused by coronal hole high speed stream
effects are likely to remain mostly brief, minor and somewhat less
frequent through at least late 2021. The southward oriented (-Bz)
component of the IMF plays a crucial but unpredictable role in
triggering all geomagnetic storms. Brief minor to moderate
geomagnetic storms may be gradually triggered when the IMF
persists in a southward orientation (-Bz) with enhanced IMF field
strength for several hours coincident with the effects of an Earth
directed coronal hole high speed stream. More frequent, longer
duration, minor to severe geomagnetic storms may be triggered
suddenly and unpredictably when the IMF persists in a southward
orientation (-Bz) with enhanced IMF field strength for several hours
or more coincident with the effects of an Earth directed fast CME.
The solar wind is likely to be slightly elevated through Thursday
due to weak residual coronal hole high speed stream effects.
The geomagnetic field is likely to be quiet through Thursday.
CME effects and solar flares strong enough to affect HF propagation
are not likely through Thursday.
Mid-latitude northern hemisphere sunset is now 38 minutes earlier
and daylength is 80 minutes shorter than it was on the June 21st.
Daylength and solar elevation angle in the northern polar region
have significantly declined due to greatly diminished summer solstice
effects.
Click here for today’s Penticton 10.7 cm solar flux index updated at 1700Z,
2000Z and 2300Z daily.
Click here for today’s three-day GFZ Planetary K Index forecast updated
every three hours.
Click here for today's SIDC Daily Bulletin on Solar and Geomagnetic
Activity updated at 1230Z daily.
Click here for today's SWPC Solar Activity Forecast Discussion updated at
0030Z and 1230Z daily.
Click here for today's Australian Space Forecast Centre Summary and
Forecast updated at 2330Z daily.
Perhaps the most useful HF propagation pages for DXers can be found at:
http://dx.qsl.net/propagation and http://www.solarham.net
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