New – Latest Area Forecast Discussion
Technical Discussion by Justin DeSautelle | Sunday, December 5, 2021
Partly sunny skies today across southern New England with winds continuing to decrease as the afternoon progresses and high pressure builds in overhead. This will relax the tight pressure gradient we’ve had and as the heights rise in the upper levels and a zonal flow will come into the area between a ridge over the western Atlantic and a deep trough digging into the central U.S. High temperatures will be in the lower 40s today which is slightly above normal. High pressure moves offshore tonight and will bring a return flow of southeast winds into the area which will keep temperatures tonight in the middle 30s to low 40s across the area. The next frontal system will be approaching the area as we go into Monday from the West and will bring a warm front end cold front through during the day on Monday. Monday morning will feature a warm front passing to our north and a southerly wind will strengthen which will increase the moisture throughout the morning. Rain showers will be coming through as the warm front passes and could even have a rumble of thunder as some elevated instability increases with a bit of cape of 200 to 500 j/kg can be possible. Monday afternoon will remain dry through the area, but skies will be mostly cloudy. Winds will continue to strengthen all day. The highest of the winds will be right before the cold front passes through Monday night and could have gusts up to 35 mph. This will also be associated with a line of showers coming through. Winds will diminish as the cold front passes and high pressure builds in at the surface for Tuesday and a zonal flow pattern will set up again. High temperatures will be below average on Tuesday with highs in the upper 30s and low 40s across the area. Next comes the question about Wednesday’s forecast with a possible developing coastal storm which the global models have but are not in good agreement right now about the exact location and track of the low-pressure area and that will be the deciding factor in everything. As a trough axis shifts through the Great Lakes Tuesday night through Wednesday, then it comes through southern New England Wednesday night and becomes negatively tilted. It’s not a highly amplified trough and there’s no blocking downstream so there isn’t a lot of time for this system to get organized and develop without something blocking it. The current thinking right now is that the storm tracks somewhere southeast of the40N/70W benchmark, but confidence is low in that right now. The models are suggesting that we do start with snow overnight Wednesday morning for a period and then transition to more of a rain snow mix as we go through Wednesday but again this is all barring that the temperature profile of the atmosphere stays cold enough to support it and that will all lean on the exact track and the amount of cold air that will be available to work with. Some accumulation of snow is looking possible for during the day on Wednesday what temperature is in the middle 30s.