The pattern in the Week Two period for May 8 through May 14 is likely to feature a continued jet stream trough in the Eastern United States. This means that the jet stream will be dipping south over the Northeast, and because the jet stream is the fast river of air high in the sky that steers storm systems and acts as a thermostat, separating cold to the north from warm to the south, this implies cool air settling south out of Canada during the period. Earlier this spring, an abundance of dry air and downsloping wind was able to offset such surges of cool air and still bring above-normal temperatures. Now, that seems a bit more difficult to do, as small storm systems moving south of New England bring the potential for a northeast wind, and at least a north wind, which would likely keep cooler than normal air in place. Elsewhere in the nation, an abundance of thunderstorms in Florida may keep temperatures below normal, while the same phenomenon will keep the Central Plains from reaching much above normal.
The greatest precipitation will fall on the south side of the active jet stream, mostly in thunderstorm complexes, but recurring in the same areas enough to boost precipitation values above normal. On the north side of the jet stream, removed from deeper moisture, above normal precipitation seems nearly impossible, but upper level disturbances may bring some showers from time to time, which is why not enough confidence could be found for a below-normal precipitation forecast in New England.
