Sunday, December 8, 2013
Our great stretch of weather continues with the mild air in place for about another week. Normally this time of year my tomatoes would be done and a frost would have taken many of the late growing flowers. This year our October temperatures are averaging just over 4 degrees above normal.
Some sunshine should break through the clouds Thursday and if we get enough afternoon sunshine some areas will see approaching 70! Even if clouds end up hanging around a bit longer, it’s going to be mild afternoon.
A quick shot of rain moves from central Pennsylvania and New York through Vermont and into Maine. The southern part of the rain will give some rain to southern New England, but the heaviest rain will west of the coastal plain. Portland and coastal areas will see a burst of showers late at night. Some of the showers could be heavy for a brief period of time.
Once the rain ends in the early morning hours Friday skies will begin to clear and sunshine returns for the afternoon Friday. It will continue to be mild.
Our weekend continues dry and seasonable. There are all sorts of activities taking place this weekend and I encourage you to check local town websites and papers to see what’s happening. Maine’s local colleges will be heading south to the annual Head of the Charles Regatta this weekend. The event takes place with picture perfect conditions for rowers and spectators alike. Winds won’t be a problem so the chop on the river should be minimal. Temperatures will rise from the upper 40s and lower 50s at sunrise just before 7AM to the lower 60s during the afternoon.
When we look at weather maps we can see how anomalous the pattern is right now by looking at what’s going on at 18,000 feet above the earth. At this level, you have about ½ the atmosphere above and below you. On the left side of the image below, the red/orange areas represent those parts of the hemisphere that are basically warmer than normal right now. The right side of the map shows the pressure systems present at the surface in the same part of the world.
The daily weather as a result of this pattern has been mild and mostly dry. While temperatures have been warm, we also have only had about 50% of the normal amount of rain. Nothing lasts forever and there are signs of a big change next week.
When patterns undergo a change, the exact placement of the jet stream plays a critical role in the day to day weather. After the upcoming weekend colder air is going to begin to move south and east into the country from Canada. The new pattern will flip the above average winds and pressures at 18,000 feet to below average.
The map below shows how the pattern is going to change next week. Notice the areas previously above average are now below. As the winds change direction at the upper levels, temperatures will fall at the lower levels.
One of the computer models has temperatures in the 30s and 40s next Thursday across a wide swath of the northeast; this would be a 20 degree or greater change from temperatures the next few days.
There is even one model showing a chance for snow in parts of the northeast during the last week of October, it’s not forecasting a big storm, but perhaps some snow in the air across parts of New England.
The last week of the month, not matter how the pattern unfolds, will certainly bring some changes and some forecasting challenges.
Gardening This Week This is a great time of year to remove some of the invasive plants in your garden. In this week's video, I head to the New England Wild Flower Society to learn about some of the worst plant offenders in the garden.
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David Epstein has been a meteorologist for more than 25 years. He spent 16 years in Boston and currently freelances at WGME13 in Portland.
In 2006, David founded GrowingWisdom.com, a business producing educational and marketing videos for the green industry. He currently is a professor at Framingham State College, teaches Jan Plan at Colby College and owns Bloomscapes Inc., a landscape design business.
David authored "Gardens Of New England" and his work has been published in Grolier's Science Annual for 10 years. He lives in South Natick, Mass., and has a summer home in Harpswell.