Weekly pattern outlook for March

The sudden stratospheric warming (SSW) event which took place earlier this month will likely lead to a noticeable pattern change across North America as we head into March.

SSWs can lead to increasing areas of high pressure aloft over the polar regions about three weeks down the road after they started. In this case there are still some unknowns, but forecast model guidance is clearly trending toward negative phases of the Arctic (AO) and North Atlantic (NAO) Oscillations in March, which can lead to colder air being forced much farther south into the midlatitudes. The one factor that is fighting this, however, may be the PNA Oscillation, which is going to stay well into the negative into at least the first two weeks of March and does not favor cold and snow in the East.

Overall it looks like the core of the cold will be into the interior West for early March before expanding eastward midmonth, but it will likely get modified somewhat.