Adjusting a nearby station's frost date assumes average night lows track frost dates
As recorded: PRISM offset from a nearby station assumes the spatial pattern of mean minimum temperature predicts the spatial pattern of last-frost date.
Promising A person has checked it against its sources. If you skip this, it still grows, just less well. The planner suggests it.
How it works
PRISM models orography, temperature inversions, slope aspect, and coastal proximity at 800m. It provides monthly mean/min/max temperature. It does not provide frost exceedance probabilities; those exist only at stations. Combining them is an inference.
The evidence
Evidence: checked against 1 source in the research-based literature.
The source
… 1971-2000 mean monthly precipitation and minimum and maximum temperature ... 30-arcsec (~800-m) grids
Plus one working note on how the sources were read. Every note is in the data download.
How this rule has changed
Every change is dated, newest first. The full record, with each reason, is in the data download.
- Sources updated
- Wording made clearer
- Sources updated
- Sources updated
- A person read the sources and confirmed it
- Details updated
- Added to the rules
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Cite this page
Milpa Gardens. “Adjusting a nearby station's frost date assumes average night lows track frost dates.” Evidence grade: Promising. https://milpa.garden/rules/prism-offset-from-nearby-station-assumes-spatial/
A garden planner built on graded evidence. Every claim states its evidence grade and links its sources on the page. Cite it with the grade, and add the date you read it.
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How we grade evidence
- Well established
- The rule names its mechanism and is settled, by sources a person has read and checked or by plain arithmetic and geometry.
- Promising
- The mechanism is named and the literature backs it. A few questions are still open.
- A good hunch
- Plausible by its mechanism, but field studies are thin, so treat it as a lean.
- Contested
- The evidence points both ways, or no study has tested it, so the planner does not enforce it.
- Refuted
- The claim did not survive its sources. It is kept so the folklore can be answered.