Tag: frost prediction

Watching the Weather

Dark stormy sky over our hoophouse and solar panels. Photo Wren Vile

Farmers and gardeners have always watched the weather, and now, as the climate crisis gets worse and the weather more chaotic, we need to hone our skills. I’ve written in the past about

Where does your weather come from?

Our mid-Atlantic weather mostly comes from one of three directions,

  • mainly from the Gulf of Mexico, (wet, maybe windy)
  • the Bermuda High Pressure area in summer, (hot and dry)
  • recurrent waves of cold air from Canada in winter (from a disrupted polar vortex).
  • Due to the erratic movement of thunderstorms, some parts of our area may experience long periods of drought. September–November is the dry season but also the hurricane season.
Such grey weather! But will it rain?
Photo Wren Vile

Find a weather station that is a good match for your area, and learn how to adapt it

We use Wunderground.com for Louisa Northside, but subtract 5F° from their forecast night lows, and mentally downgrade the chance of rain by 10%, as rain often passes us by as it scoots along the river valley north of us. I use the ten-day forecast to get the general idea, the hourly one when planning tasks, the Roanoke animated radar on the daily page to see what’s on the way and when it’s likely to arrive, and the alerts, watches and warnings. The forecast for the month is under the Calendar tab, although the further out the forecast is, the less reliable it will be. In hurricane season I check the Severe Weather tab with the Hurricane and Tropical Cyclones information.

Make yourself a Frost Alert Card of conditions that are likely to lead to an early or late frost, so you can quickly take avoiding actions without dithering.

Learn about recent average weather at your location.

I recommend Weather Spark for browsing on a rainy day, or a too-hot afternoon. “The weather year round anywhere on earth”

Weather Spark chart of average daily temperatures in Louisa County, Virginia

I rechecked our area on Weather Spark recently and realized how much has changed since I started quoted information from our Extension Service twenty or more years ago.

  • The climate in Louisa County, Virginia, is changing on average in the past ten years to drier weather with milder winters, hotter summer nights.
  • Twin Oaks is in USDA Winter Hardiness Zone 7a: the average annual minimum winter temperature is 0°F–5°F (–18°C to –15°C).
  • The average rainfall for a year is 37” (100 cm), fairly evenly distributed throughout the year, at 2.2”–3.6” (5.6-9.1 cm) per month. October is the driest, May the wettest.
  • The average daily maximum temperatures are 49°F (9.4°C) in December and January, 89°F (31.7°C) in July. The average night low temperatures are 29°F (–1.7°C) in January, 69°F (20.5°C) in July.
  • The season from last frost to first frost, is around 211 days. The average date of the last spring frost is April 24 (later than May 7 only happens one year in ten); the average date of the first fall frost is Oct 14 (earlier than Oct 1 only happens one year in ten).

Weather SparkOn Weather Spark you can study artfully-made colorful charts of temperature, precipitation, cloud coverage, humidity and tourists (!) month by month. There is a chart of average high and low temperatures over the year, and one showing the average hourly temperature over the year (we are currently in the big red blob of hot afternoons). There’s a grey and blue chart of cloud coverage, and a green one of the daily chance of rain (with touches of blue and purple frozen precipitation). The average monthly rainfall chart is all greys, as is the snowfall one. Our greatest chance of snow is February with an average of 4.2” for the month.

You can compare your nearest city to another you might dream of moving to.

There are charts of hours of daylight and twilight, sunrise and sunset, the solar elevation and azimuth (for those planning greenhouses); moon rise, set and phases for a choice of years; and – oh – humidity! Color-coded from a comfortable green, humid yellow, tan mugginess, pink oppressive and orange misery (over 75%).

There’s a chart of average wind speed over the year; wind direction, which shows my wrong belief that most of the wind here comes from the west (true in July, December and January only). There’s also (keep scrolling) a chart about the growing season, by which they mean the longest continuous period on non-freezing temperatures, although the chart provides a very visual bigger picture of periods in various temperature bands.

There’s a Growing Degree Days chart! We’re on average at 2000 F GDD at this point in July. Next is a chart of solar energy (average daily incident shortwave solar energy), with kWh peaking in June at 6.9 per day.

There’s more details, but I’m moving on.

Check extreme weather

Lightning Strike map

For when you need to know, check out Real Time Lightning Maps.org. On the map, enlarge the area you are concerned about., and watch for the activity sparking, or click for sound. There’s an explanation of how the data is gathered and what the various color dots mean.

Windy.com has a colored map with streaming arrows, and other settings for rain and thunder, clouds, temperature and more. For those at seas, you can check the waves and swell.

AirNow.gov has a quick-to-read dial of air quality, fire and smoke maps, ozone, fine particulates, lots of information about air quality

Not exactly weather, but if you experience an earthquake, go to Did You Feel It? And register your experience. It helps USGS build a clearer picture of earthquake events in your area. You can see maps of recent earthquakes globally or a world map to give understanding of tectonic plates.

 

Article on resilience in the September Growing for Market magazine

September 2012 issue of Growing for Market

The September issue of Growing for Market magazine is out, and with it, my article Building resilience into farm systems. I’ve embarked on a four-part fall and winter series of articles aimed at helping growers thrive under varying situations, some of which we have no control over.

This first article is about being prepared for whatever Nature throws at you, expecting to adapt, and building in options. I’ve sent in the second article, about  understanding and predicting conditions,for the October issue. It covers weather forecasting, frost prediction, Growing Degree Days and phenology. The next one after that will include using soil temperatures, scouting and monitoring for problems and something about on-the-spot decision-making. The last one will deal more with decision-making, reviewing results and learning from mistakes.

To read the articles, get a subscription to the magazine.

How Buildings Learn, by Stewart Brand

For those who like inspiring background reading, I recommend Stewart Brand in How  Buildings Learn: What Happens After They’re Built (Penguin 1995). He advocates for
constructing buildings that are easy to modify later, in gradual or drastic ways to meet the changing needs of the people inside. Farms can be looked at similarly. Keep as many options as possible (for crops, cover crops, crop layout) open for as long as possible. Brand’s current main activity is through The Long Now Foundation

The Art of the Long View, by Peter Schwartz

It can be helpful to do some scenario planning, which I learned about when I read The Art of the Long View, by Peter Schwartz (Doubleday, 1991). Scenario Planning is a method of making flexible long-term plans, using stories (scenarios) to help us visualize different possible futures that include not only factors we don’t control, like the weather or the market’s enthusiasm for bulb fennel, but also intangibles such as our hopes and fears, beliefs and dreams.

No time to read books? Very sad! Maybe see you at the Heritage Harvest Festival at Monticello, near Charlottesville, this Friday and Saturday.