Report

Space weather: solar flux 105, 10 below its 90-day average of 115. Maximum usable frequency 14 megahertz, measured by the Idaho Falls ionosonde via KC2G: long-distance paths open through 30 meters, 20 meters marginal, 17 meters and up closed. Critical frequency 4.0 megahertz, so 80 meters is marginal for NVIS. Daytime absorption limits 160 and 80 meters to short range. K index 5, minor geomagnetic storm. No significant flares. Data from NOAA.

Geomagnetic storms can open aurora on 6 and 2 meters. Point north and listen for raspy, buzzy signals. Coronal holes become more common as the cycle declines, bringing geomagnetic activity that repeats about every 27 days, one solar rotation. If conditions are disturbed today, watch for a repeat in about four weeks.

Sun and moon, Pacific Daylight Time: sunrise 7:08 AM, sunset 6:48 PM, day length 11 hours 40 minutes. Moonrise 12:27 AM at 58 degrees, east northeast; moonset 3:40 PM at 299 degrees, west northwest. Waning crescent, 37 percent lit. The Orionid meteor shower peaks Wednesday, October 21, a meteor scatter opportunity on 6 and 2 meters. Moonbounce: the moon peaks tomorrow at 9:02 AM, 71 degrees high and 3 percent closer than average, a good time to listen for EME signals on 2 meters and up.

Grayline enhancement on 80 through 40 meters is strongest within about half an hour of sunrise and sunset.

Amateur satellite passes for the next four hours. AO 91, FM: at 9:49 AM rising in the south, 33 degrees. The ISS, FM crossband repeater, when active: at 10:30 AM rising in the southwest, 85 degrees, overhead. SO 50, FM: at 12:07 PM rising in the southwest, 44 degrees. For the next pass, AO 91: uplink 435.25 megahertz with a 67 hertz tone, downlink 145.96. Frequencies and live status at amsat.org/status. Pass predictions at n2yo.com.

Satellite tip: on 70 centimeter downlinks, Doppler shift is about plus or minus 10 kilohertz. Start high at rise and tune down through the pass.

DX activity, via the cluster network and hamqsl.com. None spotted by West Coast stations right now. No aurora or 6 meter E-skip.

Tropospheric ducting, from balloon soundings 4 hours ago: over Oakland, a duct at 800 to 1100 feet, good for 33 centimeters and up. No matching ducts along the coast or toward Hawaii, so the enhancement is likely local. K6EEG's experimental tropo forecast, based on NOAA atmospheric model data, for the next 12 hours. Bay Area coast, peaking around 8 PM: ducting expected on 70 centimeters, 85 percent; a chance of ducting on 2 meters, 45 percent. Southern California coast, peaking around 11 AM: a chance of ducting on 70 centimeters, 55 percent; a slight chance of ducting on 2 meters, 15 percent. Nothing toward Hawaii.

Tropo openings favor horizontal antennas. For CW, try 144.05 to 144.1 megahertz on 2 meters, and 432.1 on 70 centimeters.

Events. The California QSO Party, now under way, California stations in demand. IARU Region 1UHF/Microwaves Contest, today. VHF-UHF FT8 Activity Contest, on Wednesday.

Club and community announcements. The SF Amateur Radio Club meets on the third Friday of each month, 7 PM at the Randall Museum. Visit sfarc.org for more details.

Test your go-kit monthly, and rotate batteries and supplies. Keep your FCC license information current in the ULS, including your email address. The FCC sends license notices by email.

Current weather conditions at San Francisco International Airport: Temperature 66 degrees Fahrenheit. Dew point 57 degrees Fahrenheit. Relative humidity 73 percent. Wind calm. Barometric pressure 29.90 inches of mercury, normal. Visibility 10 miles.

Batteries and radios in parked cars degrade in heat. Keep go-kit batteries somewhere cool.

National Weather Service forecast. Today: Partly sunny. High near 85, with temperatures falling to around 77 in the afternoon. Northwest wind 1 to 12 miles per hour. Tonight: Mostly clear, with a low around 61. West wind 0 to 9 miles per hour. Monday: Sunny. High near 82, with temperatures falling to around 76 in the afternoon. West wind 0 to 10 miles per hour.

Tide predictions for today at the San Francisco Embarcadero gauge. Low tide at 12:34 AM, minus 0.1 feet. High tide at 8:16 AM, 4.7 feet. Low tide at 12:48 PM, 3.3 feet. High tide at 6:32 PM, 5.6 feet.

Ocean and bay conditions. No marine advisories in effect. From the San Francisco buoy, 18 nautical miles west of the Golden Gate: significant wave height 3 feet, slight seas, dominant period 8 seconds, from the northwest. Wind at the buoy 4 knots from the north northwest. Ocean water temperature 60 degrees Fahrenheit. San Francisco Bay water temperature 66 degrees Fahrenheit. Golden Gate currents: slack water at 9:03 AM, then maximum ebb 1.5 knots at 11:39 AM, then slack water at 2:32 PM.

Air quality for field operations, from the Bay Area Air District's San Francisco Arkansas Street monitoring station. Fine particulate matter, PM2.5, is 7 micrograms per cubic meter, rated good. Ozone is 3 parts per billion. Nitrogen dioxide is 20 parts per billion. For more information visit the Bay Area Air District or openaq.org on the web.

Seismic awareness for emergency communicators: no Bay Area earthquakes of magnitude 2.5 or greater in the past 24 hours. Largest in California in the past 24 hours: magnitude 2.4, near Alum Rock. No earthquakes of magnitude 6 or greater worldwide. Seismic data from earthquake.usgs.gov.

After a strong earthquake, check in on your local emergency net, and keep transmissions brief to leave room for emergency traffic.