Wednesday 10 a.m.
Dense fog has been ruining travel plans in parts of the Midwest this morning, with hours-long delays and many cancellations of flights to and through Chicago. At this time of year, there is much less solar energy available to help evaporate the fog and lift ground-level temperatures above the saturation point. The National Weather Service issued dense fog advisories that run right to lunchtime.
In the Northeast, it is a fine day, and Thanksgiving Day will feature sunshine (although the day may start foggy). Temperatures tomorrow will climb into the 50s across New England and even higher farther south.
A cold front that crosses the Great Lakes Friday will speed well off the East coast Saturday. The cold flow behind the front will set up snow flurries and heavier squalls downwind from the Great Lakes in the Appalachians, and it would not be surprising to see some flakes in the I95 corridor for a short time.
Looking ahead to next week, cold air will be widespread across Canada. However, separate upper air current will run from the Pacific eastward across the United States. Passing storms will tap into cold air as they move past each place, but mild air flowing northward ahead of the storms seems likely to prevent any major snowfalls in the Middle Atlantic States anytime soon.
This video has more.
Note: egrets are beautiful birds.
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.
n the forecast office, we often track cold fronts with pressure maps like these. The examples are from 4AM and 10 AM today. You can see that the northern part of the front is moving more quickly than the southern end. The arrival of the front signals the start of the cooling trend that is spreading east.
The upper air flow over the East is from the west-southwest now, and some of the moisture associated with the cold front can be traced back to tropical storm activity off the Mexican west coast last week. The same moist air mass set the stage for recent flash floods in Arizona. By early next week, the upper-air flow will be coming to the Northeast region from well up in western Canada, as seen on this forecast map forecast map for next Tuesday: