A strong area of low pressure being forced to New England's north today will result in large temperature swings to open up meteorological spring. This system will first be lifting its warm front through the region, placing much of New England into the warm sector for today. With a cold front arrival not coming until this afternoon, it will allow temperatures to spike into the 40s north and 50s south. Widely scattered rain and snow showers will continue ahead of the front today across the region.
Below: AIFS showing temperature departure from average early this afternoon, showing a clear indication of where the cold front is located:
The cold front will begin to push into westernmost New England late this morning or early this afternoon. The eastward progress of the front will be relatively slow as it will not clear eastern Maine until late this evening. This slow movement will prolong the threat of scattered rain and snow showers throughout the day both ahead and along the front.
Localized heavy snow showers and isolated squalls will be possible, mainly across the northern third of New England. Frontogenesis and convergence along the cold front will allow for a line of showers to tighten up as the front slices through New England this afternoon and evening. The biggest limiting factor will be the fact that surface temperatures will be too high in the lower elevations for snow to be pulled all the way to the surface until after clearing begins behind the front. The squall threat is mainly limited to the colder higher terrain.
Below: FV3 showing potential weather this afternoon:
The bigger story with this front will be the rapidly falling temperatures. Impressive cold air advection will occur behind this front. Low-level temperatures (at the 925mb level, or about 2,500 feet above sea level) will drop 10-20°C in 6 hours from the early afternoon to late evening from west to east. With clearing behind the front, this will allow temperatures to free fall back into the teens and 20s through this evening.
Gusty winds will likely occur along and just behind the frontal passage. A temperature inversion will likely prevent wind gusts from reaching their full potential as mixing will be shallow. Still, the strong cold air advection alone should allow gusts of up to 35-45mph as the front crosses. It will likely remain breezy through the overnight and into Sunday, with wind chills around 0 for southern New England and dropping to the -20s for northern areas in the morning.
Despite full sunshine amid an ever strengthening sun angle, the strong cold air advection will ultimately give winter the win in this early battle of the seasons after spring took victories through this past week. Highs on Sunday will struggle to rise from morning lows, but that sun angle will help. Still, high temperatures are expected to remain in the teens north to 20s south. The cold will peak (or bottom out) Monday morning, when wind chills reach near the -30s across the north to the -10s across southern areas.
After the strong low pressure exits to the east of New England, an expansive area of surface high pressure will take over for Sunday through Tuesday, bringing quiet weather amid the cold stretch. This high will be to the west of New England, aiding in a northerly flow. By Monday night into Tuesday morning, the system will shift south of New England and offshore, allowing a milder return flow to ensue on Tuesday, ending this brief blast of cold air.
After Saturday, the next storm to watch will likely come around mid-week next week. All signs are pointing toward a warm and wet storm with the potential for a soaking rain event. A strong low pressure will be centered across the central US around midweek. Ahead of this storm is a strong southerly low-level jet, poised to transport high Gulf moisture northward into New England. The main system will be an inside runner with potential secondary low development off the coast.
A strong southerly flow and low-level jet developing ahead of the storm's cold front for New England is likely, which would also support a period of elevated winds. At this point, the low-level jet appears to have winds in the 70-90mph range. Naturally, not all of this will make it to the surface, and the level of mixing is uncertain this far out. With a strong inversion likely in place, winds currently look unlikely to reach their full potential, but gusty and breezy conditions will be possible.
Overall, QPF has trended upward with the storm, with a widespread half inch to inch of rain possible across the region. Guidance is currently showing low odds of over an inch anywhere in New England, but given we're 5-6 days out, the trends will continue to be watched. All of this points toward the potential for significant snowmelt across the north. With that said, the river flooding potential remains low. Rivers are mostly expected to be able to handle the incoming water and ice jam flooding potential is currently low given current ice thickness.
Below: Current forecast precipitation for Wednesday into Thursday morning:
