[RSM] W3LPL prop forecast Wed-Thur Mar 17-18

[Art Boyars]

From: donovanf at erols.com
To: pvrc reflector <pvrc at mailman.qth.net>
Cc:
Bcc:
Date: Wed, 17 Mar 2021 00:55:15 -0400 (EDT)
Subject: [PVRC] Normal propagation through midday Thursday

Long distance propagation forecast for Wednesday and Thursday, March 17-18


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

Thursday. Auroral zone and polar propagation is likely to be mostly

normal through midday Thursday, then degraded to below normal late

Thursday.



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 remain at about 78 though at

least Thursday. There are two sunspot regions on the visible disk

with only three tiny sunspots having no significant effect on HF

propagation.



We are in the middle of the March-April geomagnetic storm season

when the earth passes through the part of the interplanetary magnetic

field (IMF) with more frequent, longer duration southward oriented

magnetic field. 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

stream enhancements in the solar wind.



160 through 17 meter low and mid latitude propagation is likely to

be normal through midday Thursday, then mostly normal late

Thursday.



160 and 80 meter short path propagation to south Asia is likely to

be normal at 0200Z Thursday. 80 meter short path propagation from

North America to east Asia is likely to be normal through Thursday.

80, 40 and 30 meter long path propagation from North America to

southeast Asia at about 2330Z is likely to be normal on Wednesday

then below normal on Thursday.



30 meter auroral zone and polar propagation is likely to be mostly

normal until midday Thursday then below normal late Thursday.

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 propagation is unreliable during most of

the night in the northern hemisphere because of insufficient residual

night time F region electron density due to tiny sunspots on the visible

disk.



20 meter daytime auroral zone and polar propagation is likely to be

normal through midday Thursday, then below normal late Thursday.

Night time 20 meter propagation in the northern hemisphere continues

to be very unreliable because of insufficient residual F region electron

density due to tiny sunspots on the visible disk.



17 and 15 meter daytime mid-latitude propagation in the northern

hemisphere continues to be shorter in duration because of insufficient

F2 region electron density due to tiny sunspots on the visible disk.

12 and 10 meter daytime propagation is likely to be unreliable and

mostly limited to propagation from North America to Southern Africa,

South Atlantic, South America and South Pacific regions.



Active geomagnetic conditions *caused by coronal hole high speed*

*streams* are likely to remain mostly brief, minor and relatively

infrequent through at least late 2021. Brief minor to moderate

geomagnetic storms may be triggered when the IMF 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 enhancements in the solar wind.


IMF field strength, solar wind speed near earth, coronal hole high speed

stream effects and geomagnetic activity are likely to remain at quiescent

levels through midday Thursday when coronal hole high speed stream

enhancements in the solar wind are likely to produce disturbed

geomagnetic activity late Thursday. Earth directed CMEs or solar flares

strong enough to affect HF propagation are not likely through Thursday.



Northern hemisphere daylength is 155 minutes longer than it was on

December 21st. Sunset is now 92 minutes later than it was on

December 9th. Daylength is increasing by two minutes per day which

is steadily reducing the duration of common darkness between distant

locations in the northern hemisphere.



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:

dx.qsl.net/propagation and www.solarham.net and hamqsl.com/solar.html
<http://www.hamqsl.com/solar.html>