The North Atlantic low southeast of Greenland is likely to pass close to Reykjavík on Thursday morning

Quick answers

As of the Mon 28 Sep 12Z–18Z model runs · updated Tues., Sept. 29, 2 a.m. GMT

Where is the North Atlantic low southeast of Greenland going?

The centre is about 750 kilometres southwest of Cork, moving north at about 45 km/h. The most likely path takes it about 300 kilometres east of Tasiilaq by Thursday night.

When will the North Atlantic low southeast of Greenland be closest to Reykjavík?

Most likely Thursday, Oct. 1, around 7 a.m. GMT. Across the forecasts the closest pass comes between Thu 4 a.m. and Thu noon GMT. Most forecasts pass the centre 25–170 kilometres southwest of Reykjavík.

What is the chance it passes within 160 kilometres of Reykjavík?

81%: 8 in 10 forecasts bring the storm’s centre within 160 kilometres of Reykjavík. Rain, wind and coastal flooding can reach well beyond 160 kilometres from the centre.

How much rain could Reykjavík get while the North Atlantic low southeast of Greenland passes?

From Tue midnight (when the forecast’s rain totals start) to Thu noon GMT, the end of the window when its centre is closest to Reykjavík, the middle of NOAA’s 31 GEFS forecasts brings 35 mm of rain and melted snow to Reykjavík; nearly all bring 13 mm or more and 8 in 10 bring 25 mm or more. By Thu midnight, when that window opens, the middle forecast already has 28 mm. That is all the rain in that time, not only the North Atlantic low southeast of Greenland’s, from one model (GEFS) on a coarse grid; local official forecasts can differ. Reykjavík: rain and wind this week →

How sure is the forecast?

Path certainty: high. 170 of 185 ensemble forecasts show the storm, and they agree closely on its path. The forecasts shifted about 80 kilometres south since the previous run.

Do the AI and physics models agree?

Largely, yes. Chance within 160 kilometres of Reykjavík: AI ensembles (AIFS ENS, AIGEFS) 77%, physics ensembles (GEFS, ECMWF ENS, GEPS) 83%. By model: GEFS 94%, ECMWF ENS 86%, AIFS ENS 76%, AIGEFS 77%, GEPS 62%. By Wednesday night their middle tracks are almost on top of each other. At its deepest, the AI ensembles take it to about 955 mb and the physics ensembles to about 950 mb.

Will the North Atlantic low southeast of Greenland become a bomb cyclone?

89% of forecasts (9 in 10) deepen it fast enough to count as a “bomb” (a pressure fall of roughly 24 millibars in 24 hours, adjusted for latitude).

New to these maps? Read how to read a spaghetti map, or see the week’s rain and wind around the world on the globe.