Conversely, if it was the wrong category (i.e., above normal was forecast and below normal was observed then it was graded as "not good". Overall if a forecast was in the right category (i.e., above normal was forecast and above normal was observed) it was graded as "good". The subjective graphical grading is below. The Winter forecasts are reproduced from the 2022 Old Farmer's Almanac (Yankee Publishing, Dublin, NH) website and the corresponding observed temperature and precipitation data were downloaded from the Climate Diagnostics Center (CDC). However, it is left to the individual reader to do their own comparisons and evaluate the relative usefulness of the forecasts to their particular activity. Of the 39 temperature regions compared, 20 (51%) regions were rated as "good", only 1 (3%) as "not good" and 18 (46%) as "mixed". Of the 41 precipitation regions compared, 14 (34%) regions rated as "good", 10 (24%) as "not good" and 17 (41%) as "mixed". And if the forecast was off by a single category (i.e, above normal was predicted and it was normal) or there was a mixture of above and below in close proximity to one another then graded it as "mixed" and marked with a "0". Conversely, if it was the wrong category (i.e., above normal was forecast and below normal was observed then it was graded as "not good" with a "-". Overall if a forecast was in the right category (i.e., above normal was forecast and above normal was observed) it was graded as "good" and marked with a "+". Here is t subjective graphical grading used below. However, it must be noted that the CPC outlooks are probabilistic versus deterministic, which makes them harder to judge as right or wrong. The CPC Winter Outlook DJF 2021-2022 did better than in several of the recent winters, partly because the overall pattern ended up close to a "typical" La NiƱa. The 90-day (DJF) outlooks were retrieved from the NOAA Climate Prediction Center (CPC) archives and the corresponding observed temperature and precipitation data were downloaded from NOAA ESRL Climate Division Data. Twitter: of last year's NOAA Climate Prediction Center (CPC) 90-day precipitation and temperature forecasts for the winter period of December-February (DJF) 2021-2022 with the actual observed conditions. But will the moisture synch up with the coldest air and at the right time of day? The odds right now look better for low-level snow south of the Bay Area. The setup for later this week shows a similar strength upper low farther offshore than in 1976, with a 5210m minima on Friday morning. The hourly observations that morning showed snow falling at San Francisco International Airport, and it may have been the last snow observation recorded at SFO, since it is unlikely to have been picked up by current automated sensors. The 1000-500 mb thickness was 5221 meters. The meteorology on Feb 5, 1976, showed a cold front having moved south over the state during the overnight hours and supported by a very cold 500 mb low (5280m) west of Pt. The 1976 event was spectacularly captured by the SF Chronicle in this photo by Art Frisch. This is well documented in Mark McLaughlin's wonderful "San Francisco Snowstorms" document ( ) The event on February 5, 1887, was the snowiest on record with over 3 inches in the downtown area of the City. Historically, there have only been 11 days when snow has been recorded near sea level in downtown San Francisco, Twice on February 5th in 887 and again in 1976. The most likely scenario will be snow accumulations in areas around the bay above 1000 to 2000 feet. And the odds against it happening later this week are small, but not impossible. Granted, there have been a handful of occasions since with small pockets of cold air allowing for snow to get close to sea level, but nothing widespread. The last widespread snowfall down to near sea level in the San Francisco Bay Area was 47 years ago, on February 5, 1976.
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