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Weather Wisdom

Nice Monday, rain returns this week

Tornadoes and severe weather tore through the lower Mississippi valley last evening and the severe weather will continue in portions of that part of the Country the next couple of days. According to Joe D’Aleo at WeatherBell Analytics yesterday’s activity broke the 4th longest period without significant tornadoes in spring. This has been a very quiet April in terms of severe weather much of that due to the cool air from Canada overpowering the warm and humid air to the south.

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This morning the radar is very active. You can see on the image below all the reds and oranges. These represent strong to severe thunderstorms. There are tornado watches and severe thunderstorm warnings occurring early this morning and will likely continue all day.

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Our weekend was marred thanks to a weather pattern known as the omega block. This pattern occurs when the flow of the atmosphere which carries our storms becomes configures in a pattern representing the Greek letter Omega. You can see on the image below how this pattern looks today. The good news, at lease for the next 48 hours is that we will be under the nicer part of the block as the unsettled areas move east.
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As the block breaks down, a new storm will develop on the western part of the omega and bring a significant rain event to New England on Wednesday and Thursday. Anytime we see an inch or more of rain, I would consider it significant. The potential for street flooding and small streams flooding is there if we see rainfall amounts approach 2 or 3 inches which is possible.

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The heaviest rain appears it will fall south of the Massachusetts Turnpike, but there is still over 48 hours before the bulk of the rain occurs and the exact track of the upcoming system will determine if southern New England receives an inch of rain or closer to 2 or 3 inches of rain. The latter would create more issues, but we haven’t had enough rainfall this spring so major rivers will not reach flood stage based on the current forecast.

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I believe most of the rain will occur from midday Wednesday through the early morning Thursday. This timing could shift 6 to 8 hours either way as the storm develops and we see how the jet stream starts to unfold. It’s likely by the end of the day Thursday all areas will have seen the rain end bringing us a better forecast for Friday.

The end of the week as well as the weekend looks dry and seasonable. Temperatures will return to the upper 50s and mid 60s after being stuck in the very chilly 40s tomorrow and Wednesday. During the upcoming rain you will most certainly need warmer clothes as the lack of sunshine and raw wind of the water make it feel very chilly.

Although we have only seen 2 days in the 70s in Boston this month, April 2014 is averaging just over a degree above long-term averages. I suspect even with the upcoming chilly air, the month will be a milder one overall. In terms of rain, we are slightly under average, but after the upcoming rain the month is likely to go into the record books on the wetter side of the curve.