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

This week’s weatherTromsø, Norway

Rain is likely in Tromsø on Tuesday

Nearly all of NOAA’s 31 GEFS forecasts bring measurable rain to Tromsø Tue 2–8 a.m. CEST; 7 in 10 bring 2.5 mm or more Tue 2–8 p.m.

NOAA GEFS, 31 forecasts · Mon 28 Sep 18Z run · updated Tues., Sept. 29, 1:03 a.m. CEST · times are Tromsø’s (CEST)

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

Quick answers

Will it rain in Tromsø this week?
The best chances of measurable rain: Tuesday (nearly all forecasts, 2–8 a.m.); Wednesday (9 in 10 forecasts, 2–8 a.m.); Friday (6 in 10 forecasts, 8 p.m.–2 a.m.); Saturday (9 in 10 forecasts, 8 p.m.–2 a.m.). Drier: Thu (fewer than 2 in 10 forecasts in any six hours). Times are CEST.
How much rain will Tromsø get this week?
By Mon., Oct. 5, 8 p.m. CEST (the end of the forecast), the middle forecast has 32 mm of rain and melted snow, counting from Tue 2 a.m. 7 in 10 forecasts bring 25 mm or more in total; 2 in 10 forecasts bring 51 mm or more.
How windy will it get in Tromsø?
Gusts over 48 km/h: nearly all forecasts at Tue 2 p.m. CEST. The middle forecast’s strongest gust is 61 km/h, Tue 2 p.m. Checked every six hours, so a brief peak can fall between.
How warm or cold will it be in Tromsø?
At the six-hourly times, the middle forecast runs from 6°C (Thu 2 a.m.) to 11°C (Thu 2 p.m.) CEST. The day’s real high and low can fall between those times.
Are any storms heading for Tromsø?
No storm Stormlines tracks has 1 in 10 forecasts passing its centre within 160 kilometres of Tromsø this week.

Chance of rain, six hours at a time

Tue 2–8 a.m.: nearly all forecasts with measurable rain; middle forecast 1.5 mmTue 8 a.m.–2 p.m.: nearly all forecasts with measurable rain; middle forecast 2.5 mmTue 2–8 p.m.: nearly all forecasts with measurable rain; middle forecast 3.5 mmTue 8 p.m.–2 a.m.: nearly all forecasts with measurable rain; middle forecast 1.5 mmWed 2–8 a.m.: 9 in 10 forecasts with measurable rain; middle forecast 0.5 mmWed 8 a.m.–2 p.m.: 1 in 10 forecasts with measurable rain; middle forecast almost noneWed 2–8 p.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneWed 8 p.m.–2 a.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneThu 2–8 a.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneThu 8 a.m.–2 p.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneThu 2–8 p.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneThu 8 p.m.–2 a.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneFri 2–8 a.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneFri 8 a.m.–2 p.m.: 1 in 10 forecasts with measurable rain; middle forecast almost noneFri 2–8 p.m.: 3 in 10 forecasts with measurable rain; middle forecast almost noneFri 8 p.m.–2 a.m.: 6 in 10 forecasts with measurable rain; middle forecast 0.5 mmSat 2–8 a.m.: 6 in 10 forecasts with measurable rain; middle forecast 0.4 mmSat 8 a.m.–2 p.m.: 6 in 10 forecasts with measurable rain; middle forecast 0.5 mmSat 2–8 p.m.: 8 in 10 forecasts with measurable rain; middle forecast 1.7 mmSat 8 p.m.–2 a.m.: 9 in 10 forecasts with measurable rain; middle forecast 1.4 mmSun 2–8 a.m.: nearly all forecasts with measurable rain; middle forecast 1.3 mmSun 8 a.m.–2 p.m.: nearly all forecasts with measurable rain; middle forecast 2.0 mmSun 2–8 p.m.: 9 in 10 forecasts with measurable rain; middle forecast 1.8 mmSun 8 p.m.–2 a.m.: 9 in 10 forecasts with measurable rain; middle forecast 1.9 mmMon 2–8 a.m.: 9 in 10 forecasts with measurable rain; middle forecast 1.4 mmMon 8 a.m.–2 p.m.: 8 in 10 forecasts with measurable rain; middle forecast 2.0 mmMon 2–8 p.m.: 9 in 10 forecasts with measurable rain; middle forecast 2.0 mm

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, CEST.

The week, day by day

DayChance of rain2.5 mm or moreTotal by day’s endStrongest gustTemperature
Tue 29nearly all7 in 109.1 mm · 1 in 1062 km/h · 3 in 10 >64 km/h7°C–8°C
Wed 309 in 10<1 in 1010 mm · 1 in 1023 km/h6°C–9°C
Thu 1<1 in 10<1 in 1010 mm · 1 in 1014 km/h6°C–11°C
Fri 26 in 101 in 1011 mm · 4 in 1018 km/h7°C–11°C
Sat 39 in 103 in 1016 mm · 9 in 1027 km/h8°C–10°C
Sun 4nearly all4 in 1024 mm · nearly all36 km/h7°C–7°C
Mon 5 (part)9 in 104 in 1032 mm · nearly all26 km/h · 1 in 10 >64 km/h7°C–7°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 2 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 Tromsø

No storm Stormlines tracks has 1 in 10 forecasts passing its centre near Tromsø 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 Tromsø’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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