It wasn’t as cool this morning as yesterday, but with temperatures in the lower 40s in many places, it still was too cool for what you might expect in late May. May is likely going to end up being only a bit cooler than average month which seems counter-intuitive to what we have experienced. I often write about the idea of averages and how they are not a good indication of the actual weather or what we remember. The second half of May has been cooler than the first two weeks and since we would normally get warmer as the month progresses this is certainly clouding our collective perception of this month.
There are good aspects to the cooler weather continuing a bit further into spring. Cool weather vegetables like lettuce, kales, radish and other greens are growing really well. The crop of peas this year will also likely be really great. Flowers on trees and shrubs tend to last longer when the weather is cooler and it’s been super sleeping weather the entire month. After spending extra money on heating cost this winter, it’s good to have a break from using air conditioning early in the season.
Rainfall hasn’t been overly abundant rather just regular and steady for much of the month. When you consider the drought in California and heavy rain in other parts of the Country, we have been very fortunate with precipitation this spring.
There are two days left in meteorological spring which ends Saturday. Remember, although astronomical summer begins on June 21st, meteorologists break the seasons into 4 blocks of three months with each season ranging from 90-92 days. On Sunday, we begin meteorological summer which will end on August 31st.
If you look at the overall predictions for the summer there is fairly good agreement from various sources of a cool summer across the upper Midwest. This cool pool is roughly in the same location as the coldest of the air this winter. The northeast is forecast to be normal or slightly above normal, but with that cool pool to our west, it could translate into fewer prolonged bouts of heat this summer.
There are some indications of a cool period for the second week of June. Check out the map below which shows a wide area of the United States with forecast cool readings June 9th to the 14th.
You have likely heard about El Nino and La Nina. There are several other global oscillations like the Pacific Decadal Oscillation (PDO) and Atlantic Multi-Decadal Oscillation (AM0). The PDO went into its cool phase a few years ago and there are signs the AMO may be doing the same. Recently the AMO went negative, but this can happen for a few months even inside of a warm period. Since the AMO has been in the warm mode for 20 years it’s possible the recent cooling is just a blip. One warm mode lasted 44 years from 1926 to 1969.
I bring this up as we head into summer because cooler oceans have an enormous effect on the seasonal weather and can overwhelm other factors affecting the climate overall. If the summer ends up being cooler than average it will be interesting to look at how warm the western Atlantic becomes this year. Further, the temperatures in the Atlantic basin are an important driver of hurricane formation and can play into our winter this coming year.
If you just want to know the weekend forecast, Sunday is the best day of the two, but Saturday isn’t going to be so poor either. The first part of the day may bring early clouds, but by mid-morning all of southern Maine should be in on the sunshine. The map below predicts cloud cover for Saturday around 1PM. As with most models it’s important to note the pattern, not the exact specifics. What the map shows me is a partly cloudy sky over most of New England with the thickest clouds over the hills of western Maine.
Temperatures tomorrow will be cool, only in the lower and middle 60s. Sunday is a warmer day with highs in the lower and middle 70s. It will turn cooler along the immediate coastline in the afternoon as a sea breeze develops. Warmer air remains in place for Monday before a new chance of showers sometime in the Tuesday/Wednesday time period.