A more active weather is underway with two chance of snow between Tuesday and Martin Luther King Weekend. There is a storm system moving across the Ohio Valley that will then redevelop as it passes over Maine Tuesday night and into eastern Canada.

These situations are very tricky. The speed at which this storm intensifies will ultimately determine where the heaviest snow occurs. If the low pressure area moves faster or doesn’t become as strong as expected then the snow being forecast will be less.

The two maps below show how the low is forecast to move over the next 48 hours. Notice the storm passes east of Maine by Wednesday morning.

mapdsf

mapsdf

I reviewed this situation with my students this afternoon and we spoke about how these situations are often, but not always over forecast by the models. This doesn’t mean the snow being forecast won’t occur, but I am definitely mindful of the fact this is a close call.

snow map 33234

The morning commute will be dry on Tuesday, but the evening commute will likely take place with precipitation. Along the coast, enough warm air will make the snow quite wet and there could be some rain mixed in at times. Eventually, during the evening, the colder air from above will cool the atmosphere and the snow will become drier and lighter.

I don’t expect more than a coating to 2 inches in the Portland area, but up to 5 inches could occur as you get north of Augusta. Because of the uncertainty of this situation, a winter storm watch has been issued for areas south of Bangor with a warning further north.

wsd

The watch basically means we need more data before deciding if 6 inches of snow is likely. Until the watch becomes a warning or is dropped all together this level of uncertainty remains. Notice areas around southern Maine, including Portland have neither a watch or a warning as the likelihood of significant snow is small.

The snow comes to end before sunrise Wednesday and the morning commute should be fine. Seasonable weather continues through Friday with another possible storm in the Saturday to Sunday time frame.

The weekend storm is still only based on the computer models. As we get deeper into this week, more information will help discern what type of storm this may or may not become.

I’ll update the forecast on Twitter @growingwisdom. Please follow me there.