[RSM] W3LPL forecast Wed/26 - Thur/27

[Art Boyars]

From: donovanf at erols.com
To: PVRC <pvrc at mailman.qth.net>
Cc:
Bcc:
Date: Wed, 26 May 2021 02:14:49 -0400 (EDT)
Subject: [PVRC] Mostly below normal propagation with possible geomagnetic
storm activity through Thursday

Long distance propagation forecast for Wednesday and Thursday May 26-27


My propagation forecast derived from today's NOAA/SWPC

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



Low latitude propagation is likely to be normal on Wednesday

degrading to mostly normal on Thursday.



Mid-latitude propagation is likely to be mostly below normal

through Thursday.



Propagation through the auroral ovals and polar regions is likely

to be below normal through 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 be about 84 through Thursday.

Active region 2824 has eight small sunspots having a minor effect

on HF propagation. Active region 2825 has grown to eight tiny

sunspots having no significant effect on HF propagation.



160 and 80 meter short path propagation from North America to

VK/ZL and the south Pacific is likely to be mostly normal through

Thursday. 40 meter short path propagation to south Asia is likely

to be below normal at about 0015Z Thursday. 40 meter short path

propagation from North America to east Asia after about 0930Z

is likely to be below normal through Thursday.



30 meter propagation through the auroral ovals and polar regions

is likely to be below normal through 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 night time propagation in the northern hemisphere is likely

to improve slightly due to minor sunspot influence and longer

daylight duration.



20 meter daytime and evening propagation through the auroral ovals

and polar regions is likely to be below normal through Thursday.

20 meter northern transpolar 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 slightly due to minor sunspot influence and

longer daylight duration.



17 and 15 meter daytime long distance propagation in the northern

hemisphere is likely to improve slightly due to minor sunspot

influence and longer daylight duration. 15, 12 and 10 meter daytime

and evening long distance propagation is likely to be sporadically

enhanced by sporadic-E propagation through July.



Geomagnetic disturbances *caused by coronal hole high speed streams*

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

through at least late 2021. The north-south (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 Bz 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 Bz persists in a

southward orientation (-Bz) with enhanced IMF field strength for

several hours or more *coincident with* the effects of an earth directed

CME.



IMF field strength, solar wind speed near earth and geomagnetic

activity are likely to be at elevated to strongly enhanced levels on

Wednesday gradually declining to enhanced levels on Thursday.

Earth directed CMEs may trigger minor to major geomagnetic storms

on Wednesday due to the possible effects of interactions among multiple

CMEs. Minor geomagnetic storm activity many continue through

mid-day Thursday, possibly declining to active to unsettled geomagnetic

conditions late Thursday. Earth directed coronal high speed streams

are not likely through Thursday. There is a small chance that M-Class

solar flares may briefly degrade HF propagation on the sun-facing side

of the earth through Thursday.



Mid-latitude northern hemisphere sunset is now 63 minutes later and

daylength is 146 minutes longer than it was on the March 20th.

Daylength is increasing by just over one minute per day which is slowly

lengthening the duration of common daylight between distant locations

in the northern hemisphere. The elevation angle of the midnight sun

in the northern polar region is increasing about three degrees per week,

slowly 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 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