The pattern over the past few weeks has been, without doubt, a progressive and active one. There haven’t been any dominant areas of high or low pressure in our area, but instead the pattern has kept moving with intermittent periods of troughing and ridging as well as multiple cold fronts. If medium range forecast models are reasonably accurate, that’s about to change.
Models are in good agreement that a massive trough will develop over the Western United States during the mid to latter part of the next work week. With the mid level jet stream recessed into Northern Canada and no real high latitude blocking to speak of over the Atlantic, a ridge of high pressure will build over the East. Some forecast models even suggest the high pressure could get as strong as 1035mb — totally dominating the pattern over the Northeast.
What does this mean for us? Well, first, we’ll be in a transition period. The ridge will develop eventually, as long as model guidance isn’t totally out to lunch with the pattern progression. But first, we’ll deal with a cold front late Sunday into Monday and a few mid level perturbations early next week. Afterward, it means that we’ll likely enter a period of prolonged pleasant weather.
It won’t come without some interruptions, though, as a northeast flow initially may develop near the high pressure. This could mean some days with low clouds and onshore flow effects. But as the airmass modifies, things will likely become increasingly pleasant — and any unsettled weather will remain a few hundred miles away; whether it be over the Southeastern states (tropical moisture) or the West-Central States (upper level trough).
Until the large trough over the Western United States elongates, weakens and shifts eastward — which it eventually will — our area looks increasingly likely to experience a prolonged period of pleasant, fall weather. And to that we say, bring it on!