[RSM] W3LPL: Mostly normal but near solar min thru Sunday Aug 15

Fri Aug 13 03:49:15 EDT 2021

From: donovanf at erols.com
To: Radio Club <pvrc at mailman.qth.net>
Cc:
Bcc:
Date: Thu, 12 Aug 2021 23:03:44 -0400 (EDT)
Subject: [PVRC] Mostly normal but near solar minimum propagation is likely
to continue through Sunday August 15th

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 mostly normal through Sunday.

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 in a mostly quiet to infrequent geomagnetically active period

through mid-August when we transition into mildly active

geomagnetic activity during the last weeks in August. The more

geomagnetically active autumn equinox season begins in

September and runs through late October.

Sporadic-E propagation will be shorter duration and less reliable

through mid-August at mid-latitudes in the northern hemisphere

making long distance propagation up to about 8,000 km intermittently

available in the 17, 15, 12, 10 and 6 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 Sunday.

The sun’s visible disk has one small active region with one tiny

sunspot 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 mostly normal through Sunday.

40 meter short path propagation to south Asia at about 0015Z is likely

to be mostly normal through Sunday. 40 meter short path propagation

from North America to east Asia after about 0930Z is likely to be

mostly normal through Sunday.

30 meter propagation through the auroral ovals and polar regions

is likely to be mostly normal through Sunday. 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 improve due to increased ionizing solar

radiation in the northern high latitude regions caused by moderately

higher solar elevation angles and fairly short 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 mostly normal through Sunday.

20 meter northern transpolar propagation within a few hours of

sunrise and sunset is improving with longer duration solar ionizing

radiation on the northern polar region caused by relatively high

solar elevation angles 24 hours per day during the steadily waning

midnight sun season. 20 meter long distance propagation is

significantly degraded from mid-morning through late afternoon

at low and mid-latitudes in the northern hemisphere by F1 region

mid-day blanketing of low angle long distance propagation during

the summer. 20 meter late afternoon, nighttime and early morning

long distance propagation in the northern hemisphere is likely to

improve due to increased ionizing solar radiation in the northern

high latitude regions caused by moderately high solar elevation

angles and fairly short nights with no source of ionizing solar

radiation.

17 and 15 meter daytime long distance propagation in the northern

hemisphere is likely to be slightly improved due to increased ionizing

 solar radiation in the northern high latitude regions caused by

moderately high solar elevation angles and moderately long

mid-summer days. 17, 15, 12, 10 and 6 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 mid 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 at mostly at background levels with

a possibility of slightly enhanced intervals through Sunday due to

weak coronal hole high speed stream effects. The geomagnetic field

is likely to be mostly quiet through Sunday with the possibility of

isolated unsettled intervals late Sunday. CME effects and solar flares

strong enough to affect HF propagation are not likely through Sunday.

Mid-latitude northern hemisphere sunset is now 32 minutes earlier

and daylength is 68 minutes shorter than it was on the June 21st.

Daylength and solar elevation angle in the northern polar region

are steadily declining due to rapidly diminishing 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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