Thursday 9:30 a.m.
The dreariness of yesterday morning in the Northeast has been replaced by dazzling sunshine and deep blue skies. A fast-moving cold front will send clouds streaming across the Great Lakes then New York and New England today and tonight, then a large high pressure area from western Canada will move for the start of the weekend. You can see and hear what this high pressure area should do in this video, along with what the flow behind it should accomplish later in the weekend.
In the short burst of cold air into the eastern Great Lakes tomorrow, showers will break out in the same areas that had them last night and this morning. Since this air mass is a little colder, snow showers are likely over the higher terrain southeast of Lake Ontario. Snow showers with lightning and thunder hit the Tug Hill Plateau last night, and the same thing can happen late tonight or tomorrow morning.
Severe thunderstorms are likely to break out in the middle of the country late tomorrow and tomorrow night, then rain and thunderstorms will advance into the Great Lakes for Saturday. A switch to a southwesterly flow aloft should keep the moisture mostly north of the Middle Atlantic states for much of Sunday... but as a cold front swings around a few showers should reach the area from southern New York to Virginia on Monday.
In most of the Northeast, it is a dazzling day, with the bright sun playing off the leaves that change hue by the day. It's quite a contrast from the dull dreariness much of the region experienced the first half of the week.
This upper-air forecast map for next Saturday shows the flow that would foster a warming trend later in the week and for next weekend.
We always look back at our previous forecasts to try to learn from episodes in which we believe we could have done better. The following satellite picture shows dry weather today in just the area that originally looked like it would have more rain.
In other words, while late summers in Phoenix have gotten wetter during the last few years, Boston has become drier. Is there anything more momentous or general that we can say about this?
This enhanced infrared satellite picture shows the cold front in the Northeast and the moisture wrapping around Odille on the southwest part of the map.
Across the Central and Northern states, thunderstorms are less common at this time of year than in late spring and summer. One area that has had more thunderstorms than usual recently is across the Desert Southwest.
Last week, I mentioned that longer range computer models were suggesting a major warmup by next weekend. More recent runs have backed off on the that idea. However, there is extreme uncertainty beyond the next 7-10 days. This can be seen by looking at the following map.