[RSM] W3LPL: Mostly normal thru Friday July 30

Thu Jul 29 01:27:29 EDT 2021

From: donovanf at erols.com
To: PVRC <pvrc at mailman.qth.net>
Cc:
Bcc:
Date: Wed, 28 Jul 2021 23:43:09 -0400 (EDT)
Subject: [PVRC] Mostly normal propagation is likely through Friday July 30th

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 Friday.

Propagation crossing the auroral ovals and polar regions is likely

to be mostly normal on Thursday gradually improving to normal

on Friday.

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 June and

July compared to the more geomagnetically active equinox

seasons.

Sporadic-E propagation will continue every day through late July

at mid-latitudes in the northern hemisphere making long distance

propagation up to 15,000 km sporadically available in the

17, 15, 12, 10 and 6 meter bands from sunrise through midnight

and occasionally somewhat later.

The solar flux index (SFI) is likely to be about 79 or less through

Friday. There are two small active regions on the solar visible

disk with five very small sunspots.

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 Friday.

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

is expected to be mostly normal on Friday. 40 meter short path

propagation from North America to east Asia after about 0930Z

is likely to be mostly normal through Friday.

30 meter propagation through the auroral ovals and polar regions

is likely to be mostly normal on Thursday gradually improving to

normal on 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

improve due to increased ionizing solar radiation in the northern

high latitude regions caused by increased sunspot activity, higher

solar elevation angles and 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 on Thursday

gradually improving to normal on Friday. 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 increased sunspot activity and high solar elevation

angles 24 hours per day during the 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 increased sunspot activity,

higher solar elevation angles and 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

increased sunspot activity, high solar elevation angles and long

summer days. 17, 15, 12, 10 and 6 meter sporadic-E propagation

up to 15,000 km is likely to be sporadically available from sunrise

through midnight and occasionally later through late July.

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 moderately enhanced on Thursday

due to possible minor coronal hole high speed stream effects, then

gradually improving to slightly enhanced on Friday. The geomagnetic

field is likely to be quiet to unsettled on Thursday due to possible

minor coronal hole high speed stream effects improving to mostly

quiet with a chance of unsettled intervals on Friday. Geomagnetic

storms and solar flares strong enough to affect HF propagation are

not likely through Friday.

Mid-latitude northern hemisphere sunset is now 15 minutes earlier

and daylength is 38 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