Source: Chester County PA Area Stations - Actual Raw NWS COOP / FAA / Climate Reference Network / Delaware Environmental Observing System and NWS Trained Skywarn Program Observer CHPA-174. This summary covers one selected year or month within 1880-1889 only -- not an all-time record leaderboard across the full period of record. "Snow Totals" and the Station Summary's precip/snow columns are each station's total for the selected period. With "Entire Year" selected, the Snow Totals panel and the Station Summary show a "Cal Yr" column (Jan 1-Dec 31) alongside a season column labeled by its span (e.g. 1977-78) holding the Oct 1-Apr 30 seasonal total, and the panel is ranked by that seasonal total; the Average-row snow averages exclude any station reporting zero for the year or season, since a truly snowless season is essentially unprecedented here and a zero almost always marks a non-measuring station. Selecting a month from October through April shows that month's own snowfall alongside a season-to-date column, labeled by the season it belongs to, holding that station's total from Oct 1 through the last day of the selected month (April closes the season, so April's figure is the full season total). Zeros count toward the season-to-date average through October, November and December, when a snowless run is ordinary, and are excluded from January onward, when a cumulative zero almost always marks a station that stopped measuring. May through September fall outside the snow season and show that month alone. Stations marked † are known for this period only from the monthly summaries printed in the U.S. Signal Service / Weather Bureau Monthly Weather Review (voluntary observers' tables, 1884-1892) or, for Oct 1891 and 1893, the Pennsylvania State Weather Service monthly summaries: monthly mean temperature and precipitation, used only where that station has no daily record. Means formed from fixed-hour readings rather than the daily high and low are shifted onto the high/low basis using the months where West Chester has both (about +0.3°F on average); where the summary prints the mean of the daily maxima and minima, that is used as is. They have no Normal or Departure and appear in no daily panel, but they do count toward the monthly and annual rankings; the Average-row Departure averages only the stations that have one. Snow figures marked ‡ are published monthly totals (the snowfall lists in the Monthly Weather Review, 1882-1892) for months with no daily snow record at that station. They appear in that month's Station Summary and Snow Totals panel only, not in any daily panel, season-to-date figure or ranking. "Normal" is each station's 30-year average temperature for this same period, using the 30 years immediately preceding it (falling back to that station's full period of record if it has fewer than 10 years within that window); "Departure" is Avg. Temp minus Normal. "Precip Normal" is that station's 30-year average TOTAL precipitation for this same period (same window/fallback convention); "Precip Departure" is the period's actual precip total minus Precip Normal. The Average row's Normal/Departure and Precip Normal/Departure are the same comparisons at the county level (average of each reporting station's own normal vs. their combined actual figure); its precip/snow are likewise the average across reporting stations, not a county-wide sum. Stations missing more than 3 days of a month (15 days of a year) are left out of the Station Summary and its Average row -- the same completeness rule the ranking panel uses; a listed station whose precipitation record is incomplete shows a dash for precip. Stations listed but missing a few days are marked with their day count, e.g. "(28 of 30 days)". A month in which a station's gauge reported less than 10% of the county median (when that median is at least 1.00") is treated as a failed gauge: it is marked "gauge suspect" and left out of all precipitation figures until the data is corrected.