Wednesday: Cool north, mild south. Thursday: Snow north, 70 south!
Posted by Matt Noyes October 21, 2009 at 11:25 am
The next 36 hours will be yet another in the many examples of why I often feel like one of the luckiest meteorologists in the world. Not only am I forecasting in New England – a mecca for weather and the point of confluence for so many varied weather systems – but at NECN, a still-expanding and strengthening media outlet of nearly 4 million households, I have the true privilege of forecasting for ALL of New England. Any meteorologist worth his weight knows that to forecast from the northern tip of Maine to the southern tip of Connecticut is one of the most challenging, exciting and rewarding opportunities I could ask for. Thursday will be a day to rise up to that challenge and soak up the pure wonder of accumulating and likely plowable snow in the far North of Maine, and temperatures near 70 in Southern New England, and even into the 60s as far north as Central and perhaps Northern Vermont!
Wednesday, the weather remains quiet for all New England communities. An upper level disturbance is carrying some clouds eastward from Ontario, and the clash between cool and warm air aloft is helping new clouds to develop and redevelop from time to time. Hence, intervals of clouds and sun seems like the most prudent forecast, with the air too dry and the disturbance too weak to generate any precipitation. This, coupled with a frost-free start earlier in the day, makes for an enjoyable “hump day,” with the most dramatic feature on the weather map the big change in temperature from north to south Wednesday afternoon – 40s in the far North to 60s in Central and Southern New England.
I’m watching several disturbances to the west – one is moving east from Minnesota to Michigan, and will strengthen while straddling the Canadian border on Thursday. The counter-clockwise swirl of air around this storm will cause warm air to surge north across most of Central and Southern New England, while the dense, cold dome of air in Southern Canada settles slowly southward into the far North Country. The result will be a dramatic difference in Thursday weather, from steady snow most of the day in Northern Maine, to temperatures near 70 beneath sunshine in Southern New England! Though the warm, southwest wind may have trouble penetrating all that far into Maine, most of Vermont and New Hampshire are likely to warm, as well. Where the snow falls, though, it will fall steadily and at times heavily for northern Piscataquis, Somerset and especially Aroostook Counties in Maine. In fact, cities like Caribou, Presque Isle, Fort Kent and Madawaska stand to pick up plowable accumulations of nearly six inches, if all pans out as it appears right now!
Behind this disturbance, a bubble of cool high pressure builds south from Canada and allows for a dry but chilly Friday, with the front representing the battle of cool and warm air just to our south, and ready to return, spreading some high altitude clouds overhead by late Friday. Of course, this will only be the beginning of what will evolve into a big rainmaker for New England on Saturday. Already, we see the components at play – a tight spiral over the Rockies, indicating plenty of energy aloft, and Tropical Storm Rick, landfalling into Mexico today. The moisture associated with Rick will infuse the developing Central U.S. storm with warm and moist air, resulting in the intensification of a heavy band of precipitation that will move east as it becomes caught in the jet stream winds aloft. By Saturday, this rain will be falling across New England, and will fall most of the day, with the primary surface storm pulling into Eastern Canada, but a new surface low pressure center developing right over New England. This storm becomes a “southeaster” rather than a northeaster, because winds will blow from the southeast ahead of the storm center. In fact, some of these winds may gust strong enough to cause tree and power line damage along the coast on Saturday, while the combination of lots of moisture with a thermal boundary of incoming warmth and outgoing cold will ensure plenty of rain falls. Right now, I’m expecting an inch and a half west, and closer to two or three inches east. These estimates are preliminary, however, and may need to be modified as we near Saturday.
By Sunday, the storm is pulling away and only cold air with atmospheric energy aloft will remain, meaning sun will be blotted out frequently by bubbling clouds that will produce some sprinkles, and perhaps some mountain and hill rain or snow showers.
Folks are already wondering about Halloween – my early call is for a heavy rain event on Friday the 30th. Timing so far out is still a bit of a question, but the day certainly looks wet – I think the question is whether it can move quickly enough to be tapered to showers for most of us by trick-or-treat time, and that’s a promise I can’t make yet. By Halloween Saturday, the rain will be gone but it’s likely to be quite windy…and quite cold! So, warm costumes are advised, at least from the early view!
Have a great day… -Matt
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