[RSM] W3LPL forecast thru Sunday, Aug 1

Fri Jul 30 08:45:35 EDT 2021

From: donovanf at erols.com
To: PVRC <pvrc at mailman.qth.net>
Cc:
Bcc:
Date: Fri, 30 Jul 2021 01:52:15 -0400 (EDT)
Subject: [PVRC] Mostly normal but near solar minimum propagation is likely
through Sunday August 1st

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 is likely to be normal

through Sunday.

Propagation crossing the auroral ovals and polar regions is likely

to be mostly normal through Sunday.

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.

We are in the quiet geomagnetic activity season, only about half

as many geomagnetically disturbed days occur in July compared

to the more geomagnetically active equinox seasons.

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 76 or less through Sunday.

The sun is spotless for the first time in nearly three months.

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 seasonably 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 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 slightly improve due to increased ionizing

solar radiation in the northern high latitude regions caused by

moderately high solar elevation angles and fairly long 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 slightly to moderately elevated due to

possible minor coronal hole high speed stream effects through

Sunday and a possible glancing blow by a CME on Sunday. The

geomagnetic field is likely to be quiet to unsettled through Sunday

due to possible minor coronal hole high speed stream effects.  Brief

intervals of active geomagnetic conditions are possible through

Sunday. There is isolated chance of minor storm intervals especially

on Sunday due to a chance of a glancing blow by a CME on Sunday.

Solar flares strong enough to affect HF propagation are not likely

through Sunday.

Mid-latitude northern hemisphere sunset is now 17 minutes earlier

and daylength is 40 minutes shorter than it was on the June 21st.

Daylength and solar elevation angle in the northern polar region

are steadily declining due to steadily diminishing summer solstice

effects.

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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