NW7US Propagation Center of hfradio.org
NW7US Propagation Center

This is a sample eAlert
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SFI:271 A:147 K:5 frm 7 (78 nT) 1200 31 Oct

Frcst: SWX next 24h:severe: G4 S3 R3

Obs: SWX last 24h:extreme: G5 S3 R1

Flare: 6h hi:M1(1525Z Oct30) 24h hi:M1(0205Z Oct30)

SSN: 293 (30 Oct 2003)

Au: 8

S Wind: 1001 km/s @ 8.5 protons/cm3

Bz:  7.2 nT at 2003 Oct 31 1203Z

Global HF Propagation Conditions

for 1100Z on 31 Oct, 2003

Low Latitude: Poor

Mid Latitude: Poor

Hi  Latitude: Poor(PCA)

Warning (12): Geomagnetic K-index of 7 or greater expected

From: 2003 Oct 30 1700 UTC To: 2003 Oct 31 1600 UTC

Condition: Onset

Alert (133): Geomagnetic K-index of 6

Period: 1500-1800 UTC

Threshold Reached on 2003 Oct 30 1705 UTC

In these eAlerts, you see the following abbreviations:

SFI = The 10.7-cm Solar Flux Index.

A = The Ap Index (Planetary) from the Ak Index, a daily index of geomagnetic activity for a specific station or network of stations (represented generically here by k) derived as the average of the eight 3-hourly ak indexes in a Universal Time day.

K = The Kp index. A 3-hourly planetary index of geomagnetic activity calculated by the Institut fur Geophysik der Gottingen Universitat, F.R. Germany, from the K indexes observed at 13 stations primarily in the Northern Hemisphere. The Kp indexes, which date from 1932, are used to determine the ap indexes.

nT = NanoTeslas.

The line, "SFI:271 A:147 K:5 frm 7 (78 nT) 1200 31 Oct" is to be read as:
10.7-cm Solar Flux Index is 271.
Planetary A Index is 147
Planetary K Index is 5, down from 7
The nT reading is 78.
These readings are as of 1200 GMT, on the 31st of October (UTC).

Next, you see the forecast (Frcst).

SWX = Solar Weather. The forecast is for the next 24 hours, from the time/date of the SFI line. First, you get the overall rating of the expected solar weather conditions. In this example, it is expected to be "severe" in activity.

Then, you get specific conditions expected.

G4, S3, and R3 are levels, as defined by The NOAA Space Weather Scales tables. See http://www.sec.noaa.gov/NOAAscales/

The G scale refers to Geomagnetic Activity. The scale is:

G5 = Extreme - Kp = 9
G4 = Severe - Kp = 8
G3 = Strong - Kp = 7
G2 = Moderate - Kp = 6
G1 = Minor - Kp = 5

The S scale refers to Solar Activity. This scale is:

S5 = Extreme - Flux level of > 10 Mev = 10^5
S4 = Severe - Flux level of > 10 Mev = 10^4
S3 = Strong - Flux level of > 10 Mev = 10^3
S2 = Moderate - Flux level of > 10 Mev = 10^2
S1 = Minor - Flux level of > 10 Mev = 10

The R scale refers to Radio Blackouts. The scale is:

(NOTE: the ^-5 is -5 superscripted, and so on)

R5 = Extreme - X20 Class Flare, Flux = 2x10^-3
R4 = Severe - X10 Class Flare, Flux = 10^-3
R3 = Strong - X1 Class Flare, Flux = 10^-4
R2 = Moderate - M5 Class Flare, Flux = 5x10^-5
R1 = Minor - M1 Class Flare, Flux = 10^-5

Next, you will see the Observed Space Weather (SWX). The format is the same as for that of the Forecast, and is for the last 24 hours as of the SFI reading date and time.

Next is the Solar Flare summary. It shows the classification of the highest flare during the last 6 hours, and the last 24 hours. What is a Flare, and how are they classified?

This is then followed by the estimated SSN - Smoothed Sunspot Number - and the date of the reporting.

The Aurora Index follows, then the Solar Wind reading.

Next is the "Bz" reading - the orientation being south if this is negative, or north if this is positive. If negative, it typically means that geomagnetic activity is being increased.

After the Bz reading is the general HF conditions, shown for three latitude regions. A PCA is a "Polar Cap Absorption" event. This means that the polar regions will not typically propagation any HF radio signal.

Any further Warnings or Alerts are then listed.

Some notes of interest:

1) eAlerts are sent out any time the Kp (planetary K) index is at or above 5, and also whenever the solar flux changes. eAlerts are not sent out during times when the Kp index is below 5, even if there are a lot of changes. This keeps the eAlerts from becoming excessive. However, during days of very high geomagnetic activity, when the Kp index may stay at or rise above 5, you may receive eAlerts every three hours during the course of the storm.

2) This service is free of charge. It is provided by me, out of my free time and hobby budget. I don't have a huge hobby budget, lately, due to medical issues. If you find this service useful, and/or you find the website useful, would you please consider a donation? For full details on how you may help keep this site and the eAlert service alive, please visit:


Consider helping me out. The help you offer will go toward making this site, and this eAlert service, ever more useful to the community. This public service is NOT cheap. Bandwidth costs me about $300 USD a month.

3) You can access live propagation information with a WIRELESS WAP-enabled device at http://wap.hfradio.org/

4) You can also access the propagation information via an RSS feed. If you have a newsreader for "RSS" data, you can get the latest prop data here.

(use http://hfradio.org/propsupport/prop.rss as your channel url)

Thank you! -- Tomas, NW7US.
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copyright, 1998 - 2004, Tomas Hood (NW7US), all rights reserved.