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Nerd mode: every forecast, readouts, filters and range & bearing for weather enthusiasts

This week’s weatherLerwick (Shetland), United Kingdom

Rain is likely in Lerwick on Wednesday

Nearly all of NOAA’s 31 GEFS forecasts bring measurable rain to Lerwick Wed 1–7 p.m. BST; 4 in 10 bring 2.5 mm or more.

NOAA GEFS, 31 forecasts · Mon 28 Sep 18Z run · updated Tues., Sept. 29, 12:03 a.m. BST · times are Lerwick’s (BST)

See it on the globe For warnings, follow your national weather service.

Quick answers

Will it rain in Lerwick this week?
The best chances of measurable rain: Wednesday (nearly all forecasts, 1–7 p.m.); Friday (6 in 10 forecasts, 1–7 p.m.); Saturday (4 in 10 forecasts, 1–7 p.m.); Sunday (7 in 10 forecasts, 7 a.m.–1 p.m.). Drier: Tue, Thu (fewer than 2 in 10 forecasts in any six hours). Times are BST.
How much rain will Lerwick get this week?
By Mon., Oct. 5, 7 p.m. BST (the end of the forecast), the middle forecast has 15 mm of rain and melted snow, counting from Tue 1 a.m. 7 in 10 forecasts bring 13 mm or more in total; 2 in 10 forecasts bring 25 mm or more.
How windy will it get in Lerwick?
Gusts over 80 km/h: nearly all forecasts at Wed 1 p.m. BST. The middle forecast’s strongest gust is 101 km/h, Wed 1 p.m. Checked every six hours, so a brief peak can fall between.
How warm or cold will it be in Lerwick?
At the six-hourly times, the middle forecast runs from 12°C (Sat 7 a.m.) to 14°C (Wed 1 p.m.) BST. The day’s real high and low can fall between those times.
Are any storms heading for Lerwick?
No storm Stormlines tracks has 1 in 10 forecasts passing its centre within 160 kilometres of Lerwick this week.

Chance of rain, six hours at a time

Tue 1–7 a.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneTue 7 a.m.–1 p.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneTue 1–7 p.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneTue 7 p.m.–1 a.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneWed 1–7 a.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneWed 7 a.m.–1 p.m.: 2 in 10 forecasts with measurable rain; middle forecast almost noneWed 1–7 p.m.: nearly all forecasts with measurable rain; middle forecast 2.3 mmWed 7 p.m.–1 a.m.: 5 in 10 forecasts with measurable rain; middle forecast almost noneThu 1–7 a.m.: 1 in 10 forecasts with measurable rain; middle forecast almost noneThu 7 a.m.–1 p.m.: 2 in 10 forecasts with measurable rain; middle forecast almost noneThu 1–7 p.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneThu 7 p.m.–1 a.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneFri 1–7 a.m.: 1 in 10 forecasts with measurable rain; middle forecast almost noneFri 7 a.m.–1 p.m.: 4 in 10 forecasts with measurable rain; middle forecast almost noneFri 1–7 p.m.: 6 in 10 forecasts with measurable rain; middle forecast 0.5 mmFri 7 p.m.–1 a.m.: 5 in 10 forecasts with measurable rain; middle forecast almost noneSat 1–7 a.m.: 2 in 10 forecasts with measurable rain; middle forecast almost noneSat 7 a.m.–1 p.m.: 3 in 10 forecasts with measurable rain; middle forecast almost noneSat 1–7 p.m.: 4 in 10 forecasts with measurable rain; middle forecast almost noneSat 7 p.m.–1 a.m.: 4 in 10 forecasts with measurable rain; middle forecast almost noneSun 1–7 a.m.: 6 in 10 forecasts with measurable rain; middle forecast 0.3 mmSun 7 a.m.–1 p.m.: 7 in 10 forecasts with measurable rain; middle forecast 1.0 mmSun 1–7 p.m.: 7 in 10 forecasts with measurable rain; middle forecast 0.6 mmSun 7 p.m.–1 a.m.: 7 in 10 forecasts with measurable rain; middle forecast 0.4 mmMon 1–7 a.m.: 6 in 10 forecasts with measurable rain; middle forecast 0.5 mmMon 7 a.m.–1 p.m.: 4 in 10 forecasts with measurable rain; middle forecast almost noneMon 1–7 p.m.: 4 in 10 forecasts with measurable rain; middle forecast almost none

Each bar is the share of the 31 forecasts with measurable rain or melted snow in that six hours; the darker the bar, the more forecasts agree. Local days, BST.

The week, day by day

DayChance of rain2.5 mm or moreTotal by day’s endStrongest gustTemperature
Tue 29<1 in 10<1 in 10almost none · <1 in 1060 km/h12°C–12°C
Wed 30nearly all4 in 103.5 mm · <1 in 10101 km/h · nearly all >64 km/h13°C–14°C
Thu 12 in 101 in 103.6 mm · <1 in 1058 km/h12°C–13°C
Fri 26 in 103 in 105.4 mm · 1 in 1048 km/h · 1 in 10 >64 km/h12°C–13°C
Sat 34 in 101 in 109.0 mm · 3 in 1042 km/h12°C–12°C
Sun 47 in 102 in 1013 mm · 5 in 1058 km/h · 3 in 10 >64 km/h12°C–13°C
Mon 5 (part)6 in 102 in 1015 mm · 7 in 1051 km/h · 1 in 10 >64 km/h12°C–13°C

Chances are the highest in any six hours of the day. “Total by day’s end” is the middle forecast’s running total since Tue 1 a.m., and the share of forecasts with 13 mm or more by then; totals aren’t added up day by day, because the middle forecast of each day isn’t the same forecast. Gusts and temperatures are read every six hours.

Storms near Lerwick

No storm Stormlines tracks has 1 in 10 forecasts passing its centre near Lerwick this week. Every storm we’re tracking →

About these numbers

They come from one source, NOAA’s Global Ensemble Forecast System (GEFS): 31 runs of the same model, each started slightly differently, read at Lerwick’s coordinates on a grid about 55 km (35 miles) apart. “8 in 10 forecasts” means 8 in 10 of those runs. Nothing is adjusted for local effects such as coasts, lakes, hills or city heat, so the numbers can differ from your local official forecast, especially for snow and showers.

“Measurable rain” counts rain or melted snow in a six-hour period. Not an official forecast: follow your national weather service for warnings and decisions. How the forecasts are read: how to read the maps and the glossary.

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