[RSM] W3LPL prop forecast for Wed-Thur Mar 24-25

Wed Mar 24 23:29:38 EDT 2021

Sorry I'm a little late with this one.  Busy day.

73, Art VE4VTR/K3KU
===================
From: donovanf at erols.com
To: pvrc reflector <pvrc at mailman.qth.net>
Cc:
Bcc:
Date: Wed, 24 Mar 2021 01:13:05 -0400 (EDT)
Subject: [PVRC] Mostly normal propagation on Wednesday

Long distance propagation forecast for Wednesday and Thursday, March 24-25

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 with below normal intervals on Wednesday, gradually

improving to normal on 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 small sunspot regions on the visible

disk with six tiny sunspots having no significant effect on HF

propagation.

We are in the most disturbed weeks of the March-April geomagnetic

storm season when the earth passes through the part of the

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

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 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 Thursday. 160 and 80 meter

short path propagation to south Asia at about 0200Z is likely to be

below normal on Wednesday and normal on Thursday. 80 meter

short path propagation from North America to east Asia is likely

to be mostly below normal on Wednesday and mostly normal on

Thursday. 80, 40 and 30 meter long path propagation from North

America to southeast Asia at about 2300Z is likely to be below

normal on Wednesday and normal on Thursday.

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

below normal on Wednesday and mostly normal on 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 only six tiny sunspots on

the visible disk.

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

mostly below normal on Wednesday and mostly normal on Thursday.

20 meter northern hemisphere trans-polar propagation within a few

hours of sunrise and sunset will gradually improve with gradually

increasing electron density in the polar cap F2 region through June.

Night time 20 meter propagation in the northern hemisphere continues

to be very unreliable because of insufficient residual F region electron

density due to only six 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 only six 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 and CME 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 weakly

enhanced levels through Thursday due to waning coronal hole high

speed stream and possible coronal mass ejection (CME) effects in the

solar wind. There is a chance of a glancing blow from a CME late

Wednesday. More frequent -- although not yet earth directed --

CMEs occurring this month are an indicator of increasing solar

cycle 25 activity. Its only a matter of time before earth directed

CMEs cause more severe and longer lasting geomagnetic storms.

Solar flares strong enough to affect HF propagation are not likely

through Thursday.

Mid latitude northern hemisphere sunset is now 4 minutes later and

daylength is 10 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. Daylength at far northern

polar latitudes is increasing by 30 minutes per day and will reach

24 hours of daylight on April 7th, significantly improving 20 meter

trans-polar propagation.

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

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