Note: See special post on record Maine flooding on homepage, www.mattnoyes.net.
Not a lot of change to the general thoughts laid out here last night, except that the trend is slightly closer to New England with the upcoming front late week and weekend, but overall impact on the forecast should be small.
In the meantime, surface ridge axis will move overhead tonight and Thursday, bringing nearly calm overnight wind with dry and cool air in place. Diurnal cumulus clouds resulting from the upper level disturbance and the cold pool aloft contrasting with relatively warm land will dissipate, and this means clearing skies, light wind and dry air - great conditions for radiational cooling. Therefore, I expect colder conditions tonight than were seen last night for most of New England with widespread frost and freeze - freeze found through most of the interior. Tender plants will either have to be covered (risky given how cold it will be) - or brought inside.
Thursday is quiet here at home but PA gets into showers associated with a gentle isentropic lift on the cool side of a stationary front draped across that state. The front will also house plenty of clouds, but with an extended surface ridge developing beneath the confluent flow over New England and Eastern Quebec, we should hold these clouds off. As the ridge builds in, broad but only weak to moderate warmth and moisture streams in after having been stronger over Pennsylvania with a swath of rain, and this will bring the clouds over New England on Friday, with the rain weakening as it moves east but still capable of bringing some rain to southwest New England Thursday night, then carrying scattered showers into New England on Friday. As the warm advection weakens, though, so too will the showers, so that at least 60% of New England is unlikely to record measurable precipitation on Friday, and the other 40% is likely to find showers mostly in the morning.
Thereafter, I still like the idea of amplifying the ridge, and actually bridging the ridging from Eastern Canada up and down the Eastern US coast. This leaves us with the omega block described yesterday, and slows the atmosphere enough to squeeze out a decent Saturday and then only slowly bring in the moisture ahead of the next upper low coming in from the west and breaking down the block on Sunday. I'm not sure it's quite this easy, though, with regard to sky cover, though this description should apply to precip changes. The sky cover challenge comes from the warm and moist advection clouds on Friday being leftover under a building ridge that may result in an inversion for a time Friday evening, that will have to be mixed out Friday night to get rid of the clouds. Given a drying and cooling flow that sets in Friday night, it seems like we should succeed in mixing out the clouds on Saturday, though differential advection of warm aloft and cold at the surface will keep those clouds around into Saturday morning. That always makes me nervous with an easterly component to the wind, but for now I think we can bet on some erosion of the clouds for Saturday, especially during the afternoon.
That's all for today.
Matt
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