[RSM] W3LPL forecast Wed/26 - Thur/27
Art Boyars
artboyars at gmail.com
Wed May 26 08:44:31 EDT 2021
From: donovanf at erols.com
To: PVRC <pvrc at mailman.qth.net>
Cc:
Bcc:
Date: Wed, 26 May 2021 02:14:49 -0400 (EDT)
Subject: [PVRC] Mostly below normal propagation with possible geomagnetic
storm activity through Thursday
Long distance propagation forecast for Wednesday and Thursday May 26-27
My propagation forecast derived from today's NOAA/SWPC
web pages is published five days a week (M-F) in the Daily DX.
Low latitude propagation is likely to be normal on Wednesday
degrading to mostly normal on Thursday.
Mid-latitude propagation is likely to be mostly below normal
through Thursday.
Propagation through the auroral ovals and polar regions is likely
to be below normal through Thursday.
Click *here* <https://services.swpc.noaa.gov/images/planetary-k-index.gif>
for today’s
latest planetary Kp Index, updated every three hours.
Click *here* <http://www.hamqsl.com/solar.html> for N0NBH’s current HF Band
Conditions, updated regularly.
The solar flux index (SFI) is likely to be about 84 through Thursday.
Active region 2824 has eight small sunspots having a minor effect
on HF propagation. Active region 2825 has grown to eight tiny
sunspots having no significant effect on HF propagation.
160 and 80 meter short path propagation from North America to
VK/ZL and the south Pacific is likely to be mostly normal through
Thursday. 40 meter short path propagation to south Asia is likely
to be below normal at about 0015Z Thursday. 40 meter short path
propagation from North America to east Asia after about 0930Z
is likely to be below normal through Thursday.
30 meter propagation through the auroral ovals and polar regions
is likely to be below 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 propagation in the northern hemisphere is likely
to improve slightly due to minor sunspot influence and longer
daylight duration.
20 meter daytime and evening propagation through the auroral ovals
and polar regions is likely to be below normal through Thursday.
20 meter northern transpolar propagation within a few hours of
sunrise and sunset will steadily improve with gradually increasing
electron density in the polar F2 region through June. 20 meter
night time long distance propagation in the northern hemisphere
is likely to improve slightly due to minor sunspot influence and
longer daylight duration.
17 and 15 meter daytime long distance propagation in the northern
hemisphere is likely to improve slightly due to minor sunspot
influence and longer daylight duration. 15, 12 and 10 meter daytime
and evening long distance propagation is likely to be sporadically
enhanced by sporadic-E propagation through July.
Geomagnetic disturbances *caused by coronal hole high speed streams*
are likely to remain mostly brief, minor and somewhat less frequent
through at least late 2021. The north-south (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 Bz 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 Bz persists in a
southward orientation (-Bz) with enhanced IMF field strength for
several hours or more *coincident with* the effects of an earth directed
CME.
IMF field strength, solar wind speed near earth and geomagnetic
activity are likely to be at elevated to strongly enhanced levels on
Wednesday gradually declining to enhanced levels on Thursday.
Earth directed CMEs may trigger minor to major geomagnetic storms
on Wednesday due to the possible effects of interactions among multiple
CMEs. Minor geomagnetic storm activity many continue through
mid-day Thursday, possibly declining to active to unsettled geomagnetic
conditions late Thursday. Earth directed coronal high speed streams
are not likely through Thursday. There is a small chance that M-Class
solar flares may briefly degrade HF propagation on the sun-facing side
of the earth through Thursday.
Mid-latitude northern hemisphere sunset is now 63 minutes later and
daylength is 146 minutes longer than it was on the March 20th.
Daylength is increasing by just over one minute per day which is slowly
lengthening the duration of common daylight between distant locations
in the northern hemisphere. The elevation angle of the midnight sun
in the northern polar region is increasing about three degrees per week,
slowly improving 20 meter northern trans-polar propagation through June.
Click *here* <https://www.spaceweather.gc.ca/solarflux/sx-4-en.php> for today’s
Penticton 10.7 cm solar flux index updated at 1700Z, 2000Z and 2300Z daily.
Click *here*
<https://spaceweather.gfz-potsdam.de/fileadmin/ruggero/Kp_forecast/forecast_figures/KP_FORECAST_CURRENT.png>
for today’s
three-day GFZ Planetary K Index forecast updated every three hours.
Click *here* <http://sidc.oma.be/products/meu/> for today's SIDC Daily
Bulletin on Solar and Geomagnetic Activity updated at 1230Z daily.
Click *here* <https://www.swpc.noaa.gov/products/forecast-discussion>
for today's
SWPC Solar Activity Forecast Discussion updated at 0030Z and 1230Z daily.
Click *here* <https://www.sws.bom.gov.au/Space_Weather/1/1> 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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