[RSM] W3LPL: Complicated forecast thru Thur/27

[Art Boyars]

From: Frank W3LPL <donovanf at starpower.net>
To: PVRC <pvrc at mailman.qth.net>
Cc:
Bcc:
Date: Wed, 26 Apr 2023 02:38:22 -0400 (EDT)
Subject: [PVRC] Propagation is likely to be normal at low latitudes and
mostly normal at mid and high latitudes through Thursday. Mild to moderate
degradation is possible at mid and high latitudes mostly during local night
time hours through Thursday

My propagation forecast derived from today's NOAA/SWPC web pages and twelve
other online sources (the URLs are included this forecast) is published
five days a week (M-F) in The Daily DX. All days and times in this forecast
are in UTC (Zulu) time.

Propagation crossing low latitudes is likely to be normal through Thursday.

Propagation crossing mid-latitudes is likely to be normal on Wednesday and
mostly normal on Thursday. There is a chance of mild degradations during
local night time hours through Thursday.

Propagation crossing the auroral ovals and polar regions is likely to be
mostly normal through Thursday. Mild to moderate degradations are possible
mostly during local night time hours through Thursday.

VE3EN’s End-of-Day Solar Report is published daily at 0045Z at
https://www.solarham.net

NWRA’s Table of Space Weather Indices is updated 40 minutes after every
hour at https://spawx.nwra.com/spawx/env_latest.html SILSO’s Estimated
International Sunspot Number is updated continuously at
https://www.sidc.be/silso/DATA/EISN/EISNcurrent.png

Click *here* <https://services.swpc.noaa.gov/images/station-k-index.png>
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

Mid-latitude northern hemisphere sunset is 36 minutes later and day length
is 90 minutes longer than it was on March 20th. Sunrise is about two hours
earlier and sunset is about two hours later at the 300 km altitude of the
F2 region than at ground level.

The April 25th Estimated International Sunspot Number is 83. Today's Solar
Flux Index (SFI) is 131 and is likely to be about the same on Thursday. The
sun’s visible disk has two large, one medium and two tiny active regions
containing 13 sunspots with a total sunspot area of 505 micro-hemispheres
(about 2.5 times the surface area of the Earth).
https://www.sidc.be/spaceweatherservices/applications/solarmap

There is a slight chance of minor to moderate radio blackouts on the
daylight side of the Earth caused by M-class solar flares through Thursday.

The solar wind is likely to be strongly elevated at 500 to 600 km/second
through mid-day Thursday as a result of coronal hole high speed stream
effects and possible glancing CME influence beginning before mid-day
Thursday.

Geomagnetic activity is likely to be quiet to unsettled with a chance of
brief active intervals on Wednesday then unsettled to active with an
increased chance of brief active intervals on Thursday as a result of
coronal hole high speed stream effects and possible glancing CME influence
beginning before mid-day Thursday.

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 from North America to south Asia at about
0000Z is likely to be mostly normal through Thursday. Short path
propagation from North America to east Asia after about 0930Z is likely to
be mostly normal through Thursday.

30 meter propagation through the auroral ovals and polar regions is likely
to be mostly normal through Thursday. 30 meter propagation is always mildly
to moderately degraded within a few hours of local noon by E-region
blanketing of long distance low angle F2 propagation.

20 meter daytime and evening propagation through the auroral ovals
and polar regions is likely to be mostly normal through Thursday. 20
meter transpolar propagation within a few hours of sunrise and sunset is
likely to be mostly normal through Thursday.

17 and 15 meter long distance propagation is likely to be mostly normal
through Thursday. 17 and 15 meter long path propagation from North America
to east Asia from about 1200Z to 1400Z is likely to be mostly normal
through Thursday.
12 and 10 meter long distance propagation is likely to be mostly normal
through Thursday. 12 and 10 meter long distance propagation crossing mid
and high latitudes is beginning to experience mild effects of the normal
seasonal decline of F2 region MUFs due to reduced free electron density. 12
and 10 meter long path propagation from North America to east Asia from
about 1200Z to 1400Z is likely to be mostly normal through Thursday. 12 and
10 meter F2 propagation crossing northern hemisphere mid-latitudes is
likely to be enhanced when the solar flux index is above 120 and
geomagnetic activity is quiet to unsettled (K index of 3 or less).

There is a chance through Thursday of F2 trans-equatorial propagation (TEP)
from the southern tier of U.S. states to South America from early afternoon
through late evening. There is a chance through Thursday of oblique-TEP
from the southern tier and western U.S. states to VK/ZL and the south
Pacific from late afternoon through early evening. There is a lesser chance
that stations at mid-latitudes in the U.S. may briefly couple into both TEP
and oblique-TEP via brief geographically focused intervals of mid-latitude
sporadic-E propagation. TEP and oblique-TEP may be enhanced during strong
to severe geomagnetic storms. See K6MIO’s excellent article on 6 meter TEP,
oblique-TEP, TEP-related and mid-latitude sporadic-E linking to TEP
beginning on page 66 at:
https://k5tra.net/TechFiles/2014%20Central%20States%20whole%20book.pdf

Persistent southward orientation (-Bz) of the north-south component of the
interplanetary magnetic field (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 IMF field strength of about 5 nanoteslas
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
IMF field strength mildly stronger than 5 nanoteslas for several hours
or more coincident with the effects of an Earth directed CME (faster than
500 km/second).

Real time geomagnetic data including Bz orientation, IMF field strength,
solar wind speed and short term k-index forecast are available at
https://www.swpc.noaa.gov/products/geospace-geomagnetic-activity-plot

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 https://www.solarham.net