Source: Chester County PA Area Stations - Actual Raw NWS COOP / FAA / Climate Resource 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 grand-total 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. "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. Grand total'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); grand total's precip/snow are likewise the average across reporting stations, not a county-wide sum.