Our weekend nor’easter is now a double barreled low with part of the storm still across the mid-Atlantic region.   This storm will be moving very slowly over the next 24 hours and therefore no clearing will take place until Tuesday.

The storm brought very heavy rain and in most cases has been the most amount of rain we have seen since early June 2013, nearly 10 months ago.  That was the month Portland saw over 7 inches of rain! Remember, we had a bit of a drought much of last summer and fall and although we had above normal snowfall this winter, overall we are on the drier, not wetter side of average.

Frozen ground in some places allowed the heavy rain to runoff into the streets and caused some flooding earlier.  Some places in Rhode Island saw over 5 inches of rain, this is a tremendous amount of water in a short period of time. Here in Maine amounts have been on the order of 1 to 2 inches with 10 inches of snow across some of the northern ski areas.  

The area next to my house which is wetlands flooded and the water even came up onto my lowest rock garden.  This certainly isn’t new, but it’s been a couple of years since the water has risen this high. I think this is because the ground is still frozen solid and the water is just running off towards the lowest spot in the yard.

A storm’s purpose is to mix differences in temperature and try to balance the atmosphere. As the storm spins, sometimes its cold front catches up to its warm front. Once this has happened a storm is said to have undergone occlusion.  When a storm occludes it’s the beginning of the end of a storm, but it can still take a couple of days or longer for a system to exit an area.

During the spring, the flow at high levels of the atmosphere,  around 18,000 feet or higher can configure itself into a loop or as meteorologists call them, closed lows.  When these closed lows occur, storms have no choice but to travel in the loop and therefore make little progress away from an area.   

Think of a closed low this way.  Imagine driving on a road when you encounter a rotary.   If you enter the rotary and never exited, you would find yourself spinning in place.  On the map below notice the black lines over Long Island have closed into a loop and cutoff from the main flow moving across the country. 

In meteorology, unlike on a road, the closed lows eventually either move away or open up and become part of the normal flow again.   Cutoff lows are most common in early spring, but can occur almost any time of the year.  Some of our longest lasting snowstorms are the result of cutoff lows.  

During periods in the spring when we see cloudy damp days with light rain or drizzle and it lasts for up to a week, it’s often the result of one of these situations. 

This week, the storm that brought all the rain last night and this morning will depart and leave us with a nicer and drier period for Tuesday and Wednesday.  Temperatures during the middle of the week with reach the 40s or even lower 50s and it will really feel like spring.  Before we get there we have another 24 hours of cold and damp weather with periods of rain.  The rain could be mixed with sleet and freezing rain late tonight and some inland may see some icy spots.  This is the reason for the winter weather advisory that is in place.

When storms are in their declining stage they don’t produce a lot of accumulation of either rain or snow, therefore the flooding threat will continue to diminish and not increase.

I’ll be updating the forecast on Twitter @growingwisdom. Follow @growingwisdom

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