:Product: Geophysical Alert Message wwv.txt
:Issued: 2023 Sep 28 0905 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
# Geophysical Alert Message
Solar-terrestrial indices for 27 September follow.
Solar flux 156 and estimated planetary A-index 15.
The estimated planetary K-index at 0900 UTC on 28 September was 0.67.

No space weather storms were observed for the past 24 hours.

No space weather storms are predicted for the next 24 hours.

NOAA Alerts

Space Weather Message Code: ALTEF3
Serial Number: 3370
Issue Time: 2023 Sep 27 1246 UTC

ALERT: Electron 2MeV Integral Flux exceeded 1000pfu
Threshold Reached: 2023 Sep 27 1230 UTC
Station: GOES16

NOAA Space Weather Scale descriptions can be found at

Potential Impacts: Satellite systems may experience significant charging resulting in increased risk to satellite systems.

NOAA Observations


NOAA Scales Activity

NOAA Scales Activity
Range 1 (minor) to 5 (extreme)
NOAA Scale Past 24 hrs Current Fcst 24 hrs
Geomagnetic Storms
Solar Radiation Storms
Radio Blackouts

DX Cluster WWV announcements

0900AE5ESFI=84, A=5, K=0, No Storms -> No Storms
0900VE1DXSFI=91, A=4, K=0, No Storms -> No Storms
0900VE7CCSFI=87, A=5, K=3, No Storms -> Minor w/G1
0900VE1DXSFI=80, A=6, K=0, No Storms -> No Storms
0900AE5ESFI=143, A=4, K=1, Minor w/R1 -> Minor w/R1

Propagation Links

QRK System
Proposal for QRK system
WWV Solar Flux with A and K indexes
Proppy: Online HF propagation predictions using ITU P.533.
Online area and point-to-point predictions using the ITU application ITURHFProp.
Band Conditions - Digital Mode Automatic Propagation Reporter
PSKreporter displays the digital mode data of transmitting and receiving stations in selectable views with additional information.
DR2W DX Propagation
DX Propagation by DR2W! High resolution SNR maps in pseudo color. Propagation based on the actual sunspot number.
WA5IYX VHF Propagation Info
Current Solar-Terrestrial/Propagation Data for Your Website
You can now add the current Solar-Terrestrial/Propagation Data to your web site for free (with no ads). This data is available as a 4k, .gif image 255 X 175, 155 X 300 or 460 X 125 stickers, in multiple color schemes. Now includes calculated propagation conditions using the index and flux numbers obtained.
Solar Cycle
Solar Cycle 24 / VHF Aurora / amateur radio website.
LX4SKY Amateur Radio Activities
History of amateur radio, propagation analysis and program reviews of VOACAP, WinCAP Wizard, DX Tool Box, and 54 other HF Prop software, portable HF operation, mystery of radials, SWR, transmission lines, basics of aerial antennas, longwire and yagi antennas, Yaesu FT1000MP Mark-V review, Kenwood TS-570D(G) review, principles of amplification, RFI solutions, and lots more.
William Hepburn's VHF/UHF Tropospheric Ducting Forecast
ON4AA On-Line HF Propagation Prediction
Learn about your current local HF propagation conditions and obtain a forecast in a snap!
Propfire HF Propagation Stats for Firefox
Propfire is a propagation utility for the Firefox webbrowser. It displays current HF propagation data in your status bar.
VOACAP Quick Guide
Guide to using VOACAP, free professional HF prediction software from NTIA/ITS.
160M Propagation
KG0VL VHF Aurora Radio Research
KV5R's Getting Started in NVIS Antenna and Propagation Experimentation
Near-Vertical Incident Skywave propagation is generally considered to be F-layer reflection at angles of 70-90 degrees. It is skywave propagation without the usual skip zone. The purpose of NVIS is to communicate locally and regionally, out to about 300 miles, with moderate power, simple antennas, and no skip zone. NVIS fills in the blank spot between groundwave and low-angle skywave.
NVIS: Near Vertical Incidence Skywave
NVIS, or Near Vertical Incidence Skywave, refers to a radio propagation mode which involves the use of antennas with a very high radiation angle, approaching or reaching 90 degrees (straight up), along with selection of an appropriate frequency below the critical frequency, to establish reliable communications over a radius of 0-200 miles or so.
Amateur Chirp Project (Ionospheric Sounding)
Amateur projects to investigate radiowave propagation - G3PLX's chirp project, ionosonde database, and more...