Fresno, 9 January 2002: the visibility readings hour by hour

Fresno Yosemite International reported 1.00 mile visibility at 7:03 AM on 9 January 2002. Visibility never got above 4.00 miles all day.

The 7:03 AM reading

At 7:03 AM PST, Fresno Yosemite International Airport (USW00093193), 4.7 mi from the reference point, reported visibility of 1.00 mi. Temperature was 48.2°F, dew point 46.4°F, humidity 94%. Wind came from 180° at 3.4 mph. The sky was overcast, and present weather was mist. That reading has no sea level pressure with it.

Every hour of that day

The station sent in 33 readings between midnight and midnight. Visibility across them ran from 1.00 mi to 4.00 mi. Temperature ran from 48.0°F to 52.0°F, four degrees apart across the whole 24 hours. Humidity ran from 80% to 96%, and sea level pressure, where it was reported, from 1018.6 hPa to 1023.4 hPa. The fastest wind on any reading was 6.9 mph, and 11 of the 33 came in calm. One gust above zero was reported, 6.9 mph at 10:00 PM.

Present weather came in as fog on 21 readings, mist on 30, and haze on 3. Sky cover was overcast on 24 of the 33. Twenty four readings reported precipitation of 0.0, and the other nine had no precipitation value at all.

The table

NOAA hands these back in metric, so the numbers above are converted. Temperature and dew point come across in Celsius, visibility in kilometres, wind speed in metres per second. Present weather is decoded from the METAR abbreviation on each reading the same way a Conditions.Site report decodes it: BR is mist, FG is fog, HZ is haze.

Why this date

Central Valley visibility questions usually come down to what one instrument saw at one particular minute, not to a daily summary. So the table carries visibility, temperature, dew point, wind and sky for every reading the station sent, and you can go straight to whatever hour you need.

Before you use these numbers

These are the readings the station took, not the day's certified high and low. A real peak or trough can happen between scheduled readings, so a published daily maximum or minimum may not match what you see here.

GHCNh pools observations from more than one reporting network at the same physical station. On this date that gives you two readings a few minutes apart on several hours, 7:00 AM and 7:03 AM for instance. Both are shown. That is one station reporting twice, not two separate stations.

Visibility is measured at the station. It tells you what the sensor at the airport saw, at the airport, at that moment.

And this is one station. A full report pulls the neighbouring stations for the same moment and prints each one on its own, with its distance and how far its reading sits from the time you asked about. The station search for this area also turned up Hanford Muni AP, Madera Muni AP, Lemoore Reeves NAS and Visalia Muni AP.

Where the numbers came from

Hourly and synoptic surface observations from NOAA NCEI, Global Historical Climatology Network hourly (GHCNh), station USW00093193. Pulled for the UTC days 2002-01-09 and 2002-01-10, then cut down to the local PST day. Every reading shown carries a NOAA quality code that passes the same check Conditions.Site runs: source 335 with quality code 5, and source 223 with quality code 1.