Tag: weather forecasting

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.

 

Cooking Greens in October

 

Vates kale in the fall.
Photo Bridget Aleshire

Cooking Greens to Harvest in Central Virginia in October

Beet greens, broccoli, cauliflower, cabbage, chard, Chinese cabbage, collards, kale,  komatsuna, Maruba Santoh, pak choy, senposai, spinach, tatsoi, Tokyo Bekana turnip greens and Yukina savoy can be available here all month (and perhaps longer, depending on the temperature). OP Yukina Savoy seems more cold-hardy  and bolt-resistant than the hybrid Koji.

The new outdoor greens this month are tatsoi, kale, spinach, collards, and mizuna (if we have that outdoors).

Eat-All Greens harvests can start, if you sowed some last month. When we sowed some on September 16, we got two harvests in October and several in November.

From the hoophouse we start to harvest spinach, tatsoi, and leaves of Tokyo bekana.

Cooking Greens to Sow in Central Virginia in October

This month we finish sowing spinach and kale for overwintering outdoors (10/30 is our last chance). No more outdoor sowings until spring!

“Filler Greens”

Filler greens: short rows of Tokyo bekana, Yukina Savoy and senposai used to fill gaps in the winter hoophouse.
Photo Pam Dawling

On October 10, we sow Brassica fillers #1. These are short rows of senposai, Tokyo bekana, Yukina Savoy, Maruba Santoh,  to use to fill gaps later during the winter as soon as they occur. We simply dig them up, replant where needed and water well. Alternatively you could keep some plug flats of these plants handy. Bare-root transplanting is much easier than many fear.

During December we use the “Filler” greens plants to replace casualties and harvested heads of Tokyo bekana, Maruba Santoh, Chinese cabbage, Pak choy, Yukina Savoy and tatsoi daily. We stop filling gaps in these early harvest crops on December 25, as they will bolt in the hoophouse conditions in January at the latest.

We continue to fill gaps elsewhere with senposai until January 25. Asian greens don’t make good growth before bolting if transplanted after January 25. From January 25 to February 20 we fill all gaps everywhere with spinach transplants

Hoophouse Bed preparation and Planting

In the hoophouse we have a lot of bed preparation (all the beds except the Early Bed which we plant in September), as well as transplanting and sowing.

On October 14, we sow turnips #1: Red Round (1 row on North), Hakurei (2 rows South). Oasis, White Egg.

On October 20, we sow Filler Greens #2.

By October 23, we clear and prepare two more beds and sow spinach #2; tatsoi #2, turnips #2, chard #2 and perhaps Frills (Frilly Mustards) #1.5.

Brassica (Mustard) Salad Mix

Interesting mustard mixes are sold for salad mixes. We often mix our own Brassica Salad Mix from leftover random brassica seeds. For a single cut, almost all brassicas are suitable – just avoid turnips and radishes with prickly leaves! We sow between October 2 and November 14 for harvests during the winter, and from December 4 to February 12 for March and early April harvests.

We could, but so far we haven’t, sow Eat-All Greens in hoophouse in October.

Catch crops

Useful if a crop fails, or you have an empty space. Don’t delay, as rates of growth slow down as the temperatures and daylight decrease. Don’t expect much from sowings during the Persephone Days (less than 10 hours daylight).

Tokyo bekana is a quick-growing Asian green, for cooking or salads.
Photo Twin oaks Community

This year we grew an early catch crop of Tokyo bekana when we realized we had space that wouldn’t be needed till mid-October (for turnips). We direct sowed it August 28, weeded and thinned to 1” (2.5 cm) on September 5; weeded and thinned to 3” (7.5 cm) on September 16, using the small plants for salad. We need to clear this crop by the middle of October to sow the turnips, and the Tokyo bekana has got to a fine size.

  • Ready in 30–35 days in fall, longer in winter: brassica salad mixes, spinach, chard, salad greens (lettuce, endives, chicories), winter purslane., kale, arugula, radishes (the fast small ones and the larger winter ones), many Asian greens: Komatsuna, Maruba Santoh, mizuna, frilly mustards, Senposai, tatsoi, Tokyo Bekana and Yukina Savoy.
  • Ready in 35–45 days in fall: corn salad, land cress, sorrel, parsley and chervil.
  • Ready in 60 days in fall: beets, collards, kohlrabi, turnips

Cooking Greens to Transplant in Central Virginia in October

September sown White Russian kale (transplanted in October).
Photo Wren Vile

In our hoophouse in early October, we transplant Tokyo Bekana, Chinese cabbage, Pak choy, Yukina savoy #1,  using plants which we sowed outside under insect netting.

By October 13, we transplant chard #1, Frills #1, and Red and White Russian kales, from our outdoor nursery seedbed.

By October 21, we clear and prepare another bed and transplant 1/2 bed kale, plus Yukina Savoy, and frilly mustards. (This is our favorite crop selection to suppress nematodes),

By October 23, we clear and prepare two more beds and transplant senposai and Yukina Savoy #2 from the outdoor nursery bed.

Other Cooking Greens Tasks in Central Virginia in October

October is our month to weed and thin the fall crops in the outdoor raised beds, especially spinach and kale. We thin kale to 12” (30 cm); perhaps more space would be better, although Vates is a dwarf variety.

We put rowcover over any beds of pak choy, Chinese cabbage or Tokyo bekana we have that year. Later we weed (again!) and cover the spinach for faster growth, but leave the kale uncovered after a bad experience of Vates kale with rowcover fibers mixed in. The cooks didn’t love us!

Galinsoga dies with the frost.
Photo Wren Vile

We prefer to wait to cover spinach after frosts kill the galinsoga. As well as raised beds, we plant spinach in our cold frames, making good use of the space until the frames are needed in spring for hardening off transplants.

We roll, label and store drip tape from the fall broccoli and cabbage

Special Cooking Greens Topic for October: Get Soil Tests; Be Ready for Cold Nights.

October is a good month to do soil tests, when the soil is not too wet, and the soil temperatures are still warm (the soil life is active).

Weather Forecasting

We use Wunderground, but subtract 5F° from their forecast night lows for our nearest town, 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.

See Weatherspark.com for the typical ranges of weather in your area:

Savoy cabbage with frost.
Photo Lori Katz

Predicting Frost

Frost is more likely at Twin Oaks if:

  • The date is after 10/14 or before 4/30 (our average first and last frost dates).
  • The Wunderground forecast low for Louisa Northside is 37°F (3°C) or less.
  • The daytime high temperature was less than 70°F (21°C).
  • The temperature at sunset is less than 50°F (10°C).
  • The sky is clear.
  • The soil is dry and cool.
  • The moon is full or new (maybe to do with tides and gravity?).
  • If temperatures are falling fast, the wind is from NW and the sky is clear, then polar air may be moving in, and we’ll get a hard freeze.
  • The dew point forecast is low, close to freezing. Frost is unlikely if the dew point is 43°F or more.

Watch for cold night temperatures and decide which crops to harvest, which to cover, which to abandon:

In a double-layer hoophouse (8F/5C warmer than outside) plants can survive 14F/8C colder than outside, without extra rowcover; with thick rowcover (1.25 ozTypar/Xavan) plants can survive at least 21F/12C colder than outside.

The hoophouse winter crops are an important part of feeding ourselves year-round

Each winter I update my Winter-kill Temperatures of Cold-Hardy Vegetables.

Here are some early winter numbers for killing temperatures outdoors (without rowcover unless otherwise stated). Your results may vary!  Let me know!        

35°F (2°C): Basil.

32°F (0°C): Beans, cucumbers, eggplant, melons, okra, peppers, tomatoes.

27°F (–3°C): Many cabbage, Sugarloaf chicory.

25°F (–4°C): Some cabbage, chervil, chicory roots for chicons and hearts, Chinese Napa cabbage, dill, endive, some fava beans, annual fennel, some Asian greens (Maruba Santoh, mizuna, most pak choy, Tokyo Bekana), some onion scallions (many varieties are hardier), radicchio.

22°F (–6°C): Some arugula (some varieties are hardier), Bright Lights chard, large leaves of lettuce (protected hearts and small plants will survive colder temperatures), rhubarb stems.

20°F (–7°C): Some beets, broccoli heads (some may be OK to 15°F/-9°C), Brussels sprouts, some cabbages (the insides may still be good even if the outer leaves are damaged), celeriac, celtuce (stem lettuce), some head lettuce, some mustards/Asian greens, flat leaf parsley (curly parsley is hardier), radishes, most turnips.

15°F (–9.5°C): Some beets, beet greens, some broccoli, some cabbage, rowcovered celery, red chard (green chard is hardy to 12°F (-11°C)), cilantro, endive, some fava beans, Russian kales, kohlrabi, some lettuce, especially medium-sized plants with 4-10 leaves, curly parsley, rutabagas if not covered, broad leaf sorrel, turnip leaves, most covered turnips, winter cress.

Frosted daikon radish.
Photo Bridget Aleshire

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.