AM All Zones Update: Cut-off Low Early Week, Improving Weather Late Week

Forecast Overview

Some cooler and unsettled for will be around through middle of this week, as cut-off low slowly moves northward along the East Coast. Best chance of rainfall will be between late Tuesday and early Wednesday. Then more improving weather with a warming trend is likely late in the week into the weekend, as a ridge begins building over the East Coast. A more detailed forecast breakdown is below!

Today and Tonight

Overall mostly cloudy skies and cool conditions are expected today. Some sunshine is possible during this morning, especially north of NYC. But this should fade by increasing clouds by early this afternoon. Some showers will likely begin moving northward through the region later this afternoon and during the evening and overnight hours tonight.

Temperatures with more cloud cover and an onshore easterly flow, will likely struggle to get out of 50s during the day.  But some places that see more sunshine north of NYC, will have better shot temperatures reaching the lower 60s. Temperatures tonight will drop into the 40s with a marine airmass over the region.

NAM model forecast for later this afternoon

NAM model forecast for later this afternoon

Tuesday and Wednesday

More showers, drizzle and areas of patchy fog are possible into Tuesday morning and early afternoon. Then periods of rain and more breezy conditions are likely over the entire region during later Tuesday afternoon and evening as the cut-off low moves northward along the Mid-Atlantic coast. Some this rain could be heavy at times, as an easterly 40-50kt low-level jet and shortwave energy associated with the cut-off low moves the region.

Precipitable water values above normal support between 1” to 2” of total rainfall over parts of the region. Perhaps locally up to 3” in some spots. Some localized flooding in poor drainage and low-lying areas is possible. But more significant flooding, from heavy rainfall is not expected.

NAM model forecast for Tuesday evening

NAM model forecast for Tuesday evening

A tighter pressure gradient between high pressure over Canadian Maritimes and low pressure near Mid-Atlantic coast will also causes sustained easterly winds to increase to between 15 to 25mph over much of the region. Some gusts between to 30 to 40mph are possible, especially near the coast. But a stout inversion will keep stronger winds aloft form the low-level jet mixing down. These onshore winds, could also lead to some minor coastal flooding during high tides.

Rain may taper off again to more showers and drizzle again by Wednesday, as the cut-low begins to occlude and weaken off the New Jersey coast. But mostly cloudy and cool conditions remain. Temperatures will struggle again to out 50s through Tuesday and Wednesday.

Thursday through next weekend

Some improving weather and warmer temperatures are likely, as the weakening cut-off low moves away and more ridging builds on along the east coast. Some clearing is likely on Thursday with high temperatures in the upper 60s to lower 70s. Then temperatures may rise well into the 70s and 80s by Friday or the weekend, assuming there is more sunshine and southwest flow.

GFS model forecast showing temperatures in 70s and lower 8s0 Saturday afternoon

GFS model forecast showing temperatures in 70s and lower 8s0 Saturday afternoon

However, the pattern will still be more active, just north and west of the region, during this period. A weak cold front comes through region on Friday with some showers possible. Then some models indicate a backdoor cold front that may push south from Northern NY and New England over the weekend. We currently don’t favor this solution. But we will keep monitoring it, as it may cause more showers and cooler to return.

Stay tuned for more zone forecast updates through the week, on the cut-off low early this week and the warm-up late this week!