The dry spell is going to continue almost uninterrupted through the weekend and into next week.  This is certainly one of the nicest stretches of late April and eventually early May weather possible. Temperatures are going to run in the 60s  much of the time with a shot of cooler air for Friday and Saturday mostly along the coast. At that time highs will stay in the 50s and lower 60s. 

The cooler air at the end of the week will come from  backdoor cold front.  A back door front is a cold front that comes from the east instead of the more common west or north.  Back door fronts often come through dry, but shift the wind direction so that winds blow from the east and pull the marine air westward into eastern New England.  This time of the year, with the ocean still so cold, air temperatures will respond and our highs will drop at least 10 degrees for a day or two after the front.  In the summer a backdoor front can drop temperatures from the upper 80s to the lower 60s in under an hour, it’s an amazing shift in air mass that can take place.  I remember sitting in Portland High senior year telling my friends not to skip school and go to the beach because a back door front was going to come through.  They didn’t listen only to come home two hours later shivering. 

 

Sunday and into early next week high pressure will shift east and a milder flow of air will bring back temperatures in the 60s and lower 70s.  The mildest temperatures will be from Sanford to Bridgton in the favored heat belt, but it will also be the coolest there each morning.

 

With all this dry air temperature swings of 30 or more degrees are continuing.  Tonight, after a terrific day of sunshine and temperatures around 65F, it will quickly cool.  I expect most  areas to fall back to the 30s once again.  There could be a touch of frost in the normally colder spots.  The normal date of the final frost of the spring is early May along the coast, but a frost can happen, inland through the middle and end of the month.   Frosts at the end of May are somewhat unusual. 

 

With all this sunshine and mild temperatures we are rapidly seeing a drying of landscape. Since the 1st of March we normally would have received over 8 inches of precipitation.  That number comes from rain and the water equivalent of any snow that fell.  So far we have had only 3.80 inches of precipitation and that well over 50% of what is expected. You might be surprised at this big deficit, but remember, it takes about 10 inches of snow to make 1 inch of water so even with all that snow, it doesn’t mean we had a lot of water. 

 

The lack of rain is also exacerbating the pollen problem.   Tree pollen continues to increase and although there are minor day-to-day fluctuations in the number of pollen grains in the air, it’s going to remain very high until we see some rain.   Precipitation will help cleanse the air of the pollen. 

 

We are just starting to entire pine pollen season.  Pine pollen is that yellow dust that you see everywhere.  If you leave your windows open at night then many of the surfaces of your home are often covered by the stuff in the morning.  The pollen grains of pine trees are larger than other tree pollens and thus the reason you can see it so clearly.

 

All this nice weather is great for outdoor activities.  Any early graduations that are taking place or outdoor parties this weekend will happen without any weather issues.  The sun is very strong this time of year, about the same as late July and early August so do be sure to use sunscreen.