[RSM] W3LPL's forecast thru Thursday/12

[Art Boyars]

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From: donovanf at erols.com
To: Radio Club <pvrc at mailman.qth.net>
Cc:
Bcc:
Date: Wed, 11 Aug 2021 00:59:14 -0400 (EDT)
Subject: [PVRC] Normal but near solar minimum propagation is likely through
Thursday August 12th

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 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 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 Thursday.

The sun’s visible disk remains spotless.

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 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 normal through Thursday. 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

slightly enhanced intervals through Thursday due to weak 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 29 minutes earlier and
daylength is 64 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