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The National Park Service's Eastern Rivers and Mountains Network measures ecosystem "vital signs" in selected national parks in West Virginia, Pennsylvania, New Jersey and New York, and weather and climate is one of them. This is the network's summary of 2021 at Flight 93 National Memorial.
The Allee at Memorial Plaza, with fall foliage and orange leaves. NPS photo.
Weather versus climate
Weather is the short-term change in the atmosphere, over minutes to months: what is happening outside right now. Climate is what to expect from long-term patterns of 30 years or more. The brief's shorthand: climate is a hot summer you might expect, weather a warm rainy day you get. So the question for 2021 is how it compared with a "normal" year.
The numbers
The brief uses county-scale data for Somerset County, Pennsylvania, from 1895 to 2021, courtesy of NOAA's Climate at a Glance program. It calls 2021 very warm with near-normal total precipitation: the seventh warmest year on record and the 63rd wettest. Nine months were warmer than the long-term average, and March, August, October and December were each at least 4 °F above it.
| Month | Average temperature (°F) | Departure from average (°F) | Total precipitation (in.) | Departure from average (in.) |
|---|---|---|---|---|
| January | 27.6 | +2.6 | 2.02 | -1.47 |
| February | 25.8 | -0.7 | 3.02 | +0.07 |
| March | 40.0 | +4.6 | 3.63 | -0.30 |
| April | 47.8 | +1.7 | 3.23 | -0.56 |
| May | 55.0 | -1.6 | 5.35 | +1.10 |
| June | 66.1 | +1.6 | 3.27 | -1.31 |
| July | 69.2 | +0.9 | 4.39 | +0.06 |
| August | 70.6 | +4.0 | 5.18 | +1.16 |
| September | 62.1 | +1.7 | 6.71 | +3.24 |
| October | 55.7 | +6.2 | 2.94 | -0.19 |
| November | 37.4 | -1.1 | 0.93 | -2.09 |
| December | 37.5 | +8.8 | 3.46 | +0.15 |
| Year | 49.6 | +2.4 | 44.13 | -0.13 |
Departures compare 2021 with the long-term averages for 1895 to 2020. In all, 44.13 inches of precipitation fell, just 0.13 inch less than the long-term average. September was the wettest month relative to its average, and November the driest.
A long view
Data for the county show annual average temperature rising by about 0.09 °F per decade, and annual total precipitation by about 0.43 inch per decade, since 1895.
Annual average temperature and annual total precipitation for Somerset County, Pennsylvania, 1895 to 2021; dashed lines show linear estimates of change. Figure from the National Park Service's page.
National Park Service scientists have also used models to estimate that by 2100 the park's annual average temperature will rise by 3.1 to 9.2 °F, from the best-case to the worst-case scenario, and that annual total precipitation will rise by 6 to 12 percent, as reported by Gonzalez and others in 2018.
Sources
- National Park Service, Eastern Rivers and Mountains Network, "2021 Weather In Review: Flight 93 National Memorial" (https://www.nps.gov/articles/000/2021-weather-in-review-flight-93-national-memorial.htm); the seasonal ranking charts are left out; rewritten in hubnx's own words.
In these publicationsFlight 93 National Memorial
Licence: CC0 1.0 (public domain) · Adapted from www.nps.gov
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