Monday 9 a.m.
It has been quite dry recently in the Middle Atlantic and southern New England areas. When it is dry and becomes windy, there is increased danger of wildfires that can spread out of control. Some tragic fires have already occurred.
As an upper-air trough strengthens over the Northeast during the next few days, many places will have a a few showers, but no persistent rainfall is in sight... so the danger will continue. The main effect of the trough will be to set up and maintain a chilly weather pattern for the Great Lakes and Northeast. Downwind from the Great Lakes and into the Appalachians, it will get cold enough for some snow showers. Over the highest terrain, there will be enough to cause slippery conditions.
The video explains how weather features should progress between now and next weekend.
While the Northeast is chilly, there is very warm and humid air in the southern Plains. There is an elevated tornado risk in central and western Oklahoma and north-central Texas, as shown on the following map. A strong Pacific trough will move inland on Wednesday, and some of its energy could help spawn severe thunderstorms and tornadoes in the South Central states later in the week.
The reason for this is a growing and then stalling storm aloft. This map shows the predicted circulation around the storm on Wednesday evening, showing how the moisture could keep going round and round until the storm leaves.
This mornng, showers were moving across the lower Great Lakes region. A band of thunderstorms developed near Chicago before 6:30 a.m. CT and reached the southwest Michigan shoreline an hour later (8:30 a.m. ET). The following maps show the shower zone and Chicago area lightning.
The tropics have been more active recently. This map shows various entities that area being tracked and analyzed. Hurricane Gonzalo stands out clearly.
A couple of days ago, the storm entering the East had a stronger circulation than it does now. Here is the pressure analysis from earlier this morning. Several minor disturbance can be seen, and trough lines representing those have been sketched on the map. Note that there is little difference in temperature from western Pennsylvania to Wisconsin.
The rain band is only 100-200 miles wide, but it is moving slowly. This map shows its location at 10 a.m. today. Once the main rain band passes, it won't be quite as warm as it was when the rain started. However, by mid-October standard, it will still be mild.
On some days, there are so many "little things" that it is difficult to identify the players. Today, we see two systems dominating: the low pressure area on the left (west) and the high pressure area to the right (east). The cold front associated with the low pressure area is helping to support bands of rain.