{
  "address": "104e411069dd039c5ce057973264d2b4",
  "category": "other",
  "question": "Using the NWS 2001 formula, what is the wind chill at 5 degrees F with a 25 mph wind?",
  "answer": "-17 degrees F",
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  "madeAt": "2026-09-30T22:39:30.722Z",
  "validUntil": null,
  "validityClass": "forever",
  "sources": [
    {
      "label": "Wind Chill Chart and the 2001 NWS wind chill formula",
      "url": "https://www.weather.gov/safety/cold-wind-chill-chart"
    }
  ],
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  "answerMethod": "method",
  "unsourced": false,
  "source": {
    "kind": "url",
    "value": "https://www.weather.gov/safety/cold-wind-chill-chart",
    "retrieved_utc": "2026-09-30T19:52:00Z"
  },
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  "cardContractVersion": "card_contract/1",
  "deck_id": "method-deck",
  "deck_title": "Method Deck",
  "method": {
    "name": "Wind chill (US NWS 2001 formula)",
    "version": "1",
    "source_url_or_file": "methods/wind-chill-us-nws.cjs",
    "sha256_of_method_file": "a6f47736bb6ac3eeab0ba208400dfc8003a23756c464cc4d540df6af330f7b47"
  },
  "receipt": {
    "inSubstrate": false,
    "local": true,
    "modelCallsAtMint": 0,
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  },
  "method_deck": {
    "inputs": [
      {
        "name": "temp_f",
        "type": "number",
        "unit": "degrees F",
        "required": true,
        "description": "Air temperature.",
        "max": 50
      },
      {
        "name": "wind_mph",
        "type": "number",
        "unit": "mph",
        "required": true,
        "description": "Sustained wind speed.",
        "min": 3
      }
    ],
    "outputs": [
      {
        "name": "wind_chill_f",
        "unit": "degrees F",
        "description": "Wind chill temperature."
      }
    ],
    "steps": [
      "NWS 2001 wind chill formula: WC = 35.74 + 0.6215*T - 35.75*V^0.16 + 0.4275*T*V^0.16, where T is air temperature in F and V is wind speed in mph.",
      "Valid range: temperature at or below 50 F and wind speed at or above 3 mph. Outside this range the formula is not meaningful.",
      "Round to the nearest whole degree."
    ],
    "constants": [
      {
        "name": "wind_chill_valid_max_temp_f",
        "value": 50,
        "unit": "degrees F",
        "source": 0
      },
      {
        "name": "wind_chill_valid_min_wind_mph",
        "value": 3,
        "unit": "mph",
        "source": 0
      }
    ],
    "examples": [
      {
        "name": "worked example",
        "inputs": {
          "temp_f": 5,
          "wind_mph": 25
        },
        "expected": {
          "answer": "-17 degrees F"
        },
        "check": "By hand: 25^0.16 = e^(0.16*ln25) = e^0.51502 = 1.6737; WC = 35.74 + 3.1075 - 35.75*1.6737 + 0.4275*5*1.6737 = 38.8475 - 59.8348 + 3.5776 = -17.41, rounding to -17."
      },
      {
        "name": "test vector: milder cold",
        "inputs": {
          "temp_f": 30,
          "wind_mph": 10
        },
        "expected": {
          "answer": "21 degrees F"
        },
        "check": "By hand: 10^0.16 = e^(0.16*ln10) = e^0.36841 = 1.4454; WC = 35.74 + 18.645 - 35.75*1.4454 + 0.4275*30*1.4454 = 54.385 - 51.673 + 18.537 = 21.25, rounding to 21."
      }
    ],
    "disclaimer": null,
    "deck_category": "other"
  },
  "status": "minted",
  "kind": "method",
  "provenanceClass": "own_question",
  "provenance": {
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    "chain": [
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        "source": {
          "kind": "url",
          "value": "https://www.weather.gov/safety/cold-wind-chill-chart",
          "retrieved_utc": "2026-09-30T19:52:00Z"
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        "supersedes": null,
        "added_utc": "2026-09-30T22:39:30.722Z",
        "added_by": "method:Wind chill (US NWS 2001 formula)",
        "why": "the method that computed this answer",
        "check": null,
        "status_label": "pending",
        "signature": null
      }
    ]
  }
}