[RSM] W3LPL: "Happy days are here again"

[Art Boyars]

rom: donovanf at erols.com
To: PVRC <pvrc at mailman.qth.net>
Cc:
Bcc:
Date: Tue, 20 Apr 2021 02:02:58 -0400 (EDT)
Subject: [PVRC] Happy days are here again

Long distance propagation forecast for Tuesday and Wednesday, April 20-21


My propagation forecast derived from today's NOAA/SWPC web

pages is published five days a week (M-F) in the Daily DX.



Low and mid-latitude propagation is likely to be normal through

Wednesday. High latitude propagation is likely to be mostly normal

through Wednesday with possible below normal intervals early Tuesday.



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.


The solar flux index (SFI) is likely to be 85 or higher over the next

week. This may be the significant increase in solar activity we’ve

been anticipating. Two active regions contain a total of 16 sunspots.



We are beginning to exit the most disturbed weeks of the March-April

geomagnetic storm season when the earth is passing through the part

of the interplanetary magnetic field (IMF) with the most frequent,

longest duration southward oriented IMF. Approximately twice as

many brief minor and moderate geomagnetic storms occur during

March and April compared to the quieter IMF during June and July.

Brief minor to moderate geomagnetic storms may be triggered with

little warning when the IMF rotates to a southward orientation and

persists for several hours *coincident with* the effects of earth directed

coronal hole high speed streams and coronal mass ejection (CME)

enhancements in the solar wind.



160 and 80 meter short path propagation from North America to

VK/ZL is likely to be normal through Wednesday. 80 and 40 meter

short path propagation to south Asia is likely to be mostly normal

at about 0030Z Wednesday. 80 and 40 meter short path propagation

from North America to east Asia after about 0900Z is likely to be

mostly normal through Wednesday with possible below normal

intervals early Tuesday.



30 meter propagation through the auroral ovals and across polar

regions is likely to be mostly normal through Wednesday with

possible below normal intervals Tuesday. 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 propagation is likely to improve due to

solar flux of 85 or higher.



20 meter daytime and evening propagation through the auroral ovals

and across polar regions is likely to be mostly normal through

Wednesday with possible below normal intervals early Tuesday.

20 meter northern trans-polar propagation within a few hours of

sunrise and sunset will steadily improve with gradually increasing

electron density in the polar F2 region through June. 20 meter

night time long distance propagation in the northern hemisphere

is likely to improve through Wednesday due to solar flux of 85 or higher.



17 and 15 meter daytime long distance propagation in the northern

hemisphere is likely to improve through at least Wednesday due to

solar flux of 85 or higher. 12 and 10 meter daytime long distance

propagation is likely to be mostly unreliable and limited to

propagation from North America to Southern Africa, South Atlantic,

South America and South Pacific regions.



Geomagnetic disturbances *caused by coronal hole high speed streams*

are likely to remain mostly brief, minor and less frequent through

at least late 2021. The north-south (Bz) component of the IMF plays

a crucial role in triggering brief minor to moderate geomagnetic storms

when it persists in a southward orientation (-Bz) with enhanced field

strength for several hours *coincident with* the effects of earth directed

coronal hole high speed stream or CME enhancements in the solar wind.

IMF field strength, solar wind speed near earth and geomagnetic activity

are likely to remain at enhanced levels through early Tuesday due to

waning coronal hole high speed stream effects, gradually improving to

nominal levels through Wednesday. Geomagnetic storms and earth directed

CMEs and solar flares strong enough to affect HF propagation are not likely

through Wednesday.



Mid latitude northern hemisphere sunset is now 30 minutes later and

daylength is 77 minutes longer than it was on the March 20th. Daylength

is increasing by two minutes per day which is steadily lengthening the

duration of common daylight between distant locations in the northern

hemisphere. Solar elevation in the northern polar region is increasing

about three degrees per week, steadily improving 20 meter northern

trans-polar propagation through June.



Click *here* <https://www.spaceweather.gc.ca/solarflux/sx-4-en.php> for today’s
Penticton 10.7 cm solar flux index updated at 1800Z, 2000Z and 2200Z 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