[RSM] W3LPL: Mostly normal thru Sunday July 23

Fri Jul 23 14:33:50 EDT 2021

From: donovanf at erols.com
To: Reflector PVRC <pvrc at mailman.qth.net>
Cc:
Bcc:
Date: Fri, 23 Jul 2021 00:30:43 -0400 (EDT)
Subject: [PVRC] Mostly normal propagation is likely through Sunday July 23nd

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 with possible below normal

intervals from late Friday through early Saturday.

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 occurs every day during June and 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 87 through Sunday.

There are six small active regions on the solar visible disk with

17 mostly tiny 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

Sunday. 40 meter short path propagation to south Asia at about

0015Z may be below normal on Saturday and is likely to be

mostly normal on Sunday. 40 meter short path propagation from

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

mostly normal on Friday, with the possibility of below normal

intervals on Saturday, and mostly normal on Sunday.

30 meter propagation through the auroral ovals and polar regions

is likely to be is likely to be mostly normal, with possible below

normal intervals from late Friday through early Saturday.

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 through

Sunday, with possible below normal intervals from late Friday

through early Saturday. 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 improve due to increased

ionizing solar radiation in the northern high latitude regions

caused by increased sunspot activity, high solar elevation

angles and long 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 slightly enhanced through Sunday

but with the possibility of moderate enhancement from late

Friday through early Saturday. The geomagnetic field is likely

to be unsettled to active with a small chance of minor storm levels

late Friday due to a possible CME glancing blow. The geomagnetic

field is likely to be unsettled to active as possible CME effects

gradually wane through mid-day Saturday, returning to mostly

quiet from late Saturday through Sunday. Coronal hole high stream

effects and solar flares strong enough to affect HF propagation

are not likely through Sunday.

Mid-latitude northern hemisphere sunset is now 10 minutes earlier

and daylength is 30 minutes shorter than it was on the June 21st.

Daylength and solar elevation angle in the northern polar region

are steadily declining due to waning 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