Beautiful weather has held steady over the region for the past week. This period encompassed our first two 80+ degree days of the year. The one thing lacking was rainfall. Due to a strong upper level ridge over the region, all storms were deflected away. This is all due to very strong blocking in the western Atlantic and East Coast. This blocking is soon to be interupted however, by an intensifying jet stream that will blast into the region early next week.
Tomorrow night, a front will lift north of the region, introducing warm air advection. Frontal system currently triggering severe weather in the Great Lakes region and some wintry weather further west will push northeast above the ridge and weaken, bringing some showers to the region through Sunday morning, with only very light accumulations expected.
A stronger system will push east into New York with a significant load of moisture from the Gulf along for the ride, and support added with southerly flow off of the Atlantic. Low pressure will curve to the north, with a secondary low developing just south of the region. With strong low and mid level vertical lift, periods of heavy rain will be likely through Monday Night and into Tuesday, with leftover showers behind the storm lingering into Tuesday Night. At this time, rainfall looks to be on the order of 1 to 2 inches, however higher amounts are possible in any areas of enhanced convection.
Wednesday morning, cold air advection will drop temperatures to around freezing. So any lingering showers could change to snow. There is nothing ruling out a few flakes in Keene.
This storm wraps together very tightly starting Tuesday, and mid level trough tilts negative to the point of its axis nearly pointing east. Primary low is nearly stationary in southern Ontario by Wednesday morning. The 500mb trough closes off with a minimum height of 5280m. Scattered precipitation will develop in association with low. 850mb temperatures will be down below 0C, and with cloudy skies sticking around through the rest of the week, we could see some scattered rain or snow showers.
The really interesting part begins Wednesday Night as both the ECMWF and the GFS are indicating the low pressure in Ontario splitting, with one low heading northeast and the other rotating around the mid level trough to a point near the 40/70 benchmark. Late season nor'easter? Certainly possible. Current modelling taken verbatem actually gives interior SNE some accumulating snows on Thursday (yes, that is May 1st). While this is unlikely, future model runs should be monitored for consistency. Given the theme all winter long of models trending to the northwest, a cold rain is probably a more realistic take on the model output at the moment.
The pattern looks like it will remain chilly for the first week of May, but also with some moderation.
1 comment:
Interesting blog.
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