[RSM] W3LPL: Normal but... thru Fri/20

[Art Boyars]

From: donovanf at erols.com
To: PVRC Submissions <pvrc at mailman.qth.net>
Cc:
Bcc:
Date: Wed, 18 Aug 2021 23:50:43 -0400 (EDT)
Subject: [PVRC] Normal but near solar minimum propagation is likely to
continue through Friday August 20th

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 Friday.



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 74 or less through Friday.

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

sunspots having little 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 Friday. 40 meter

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

normal through Friday. 40 meter short path propagation from

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

through Friday.



30 meter propagation through the auroral ovals and polar regions

is likely to be normal through Friday. 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 Friday. 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 at background levels through Friday.

The geomagnetic field is likely to be quiet on Thursday with a

possibility of unsettled intervals Friday due to coronal hole

high speed stream effects. CME effects and solar flares strong

enough to affect HF propagation are not likely through Friday.



Mid-latitude northern hemisphere sunset is now 39 minutes earlier

and daylength is 82 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