Following the coastal low late last week that drenched Pennsylvania but failed to extend north into the area as originally predicted, the relatively inactive pattern that was mostly interrupted by last week’s severe weather continues into this week, with little rain and temperatures generally slightly above average. Despite the absence of a stormier pattern, a stronger cool down is expected towards next weekend.
Observations for Wednesday through Friday, October 9-11, have been added in a separate post.
Tonight – Wednesday: Dry, Slightly Warmer Than Average
As the storm updates for the coastal low and observations for October 9-11 noted, the coastal low that stalled south of the region failed to produce widespread rain over the area, which can partly be attributed to dry air aloft and subsidence between convection well offshore and rain bands stalled over Pennsylvania. Temperatures warmed up into the 70s today for most of the area, but with a noticeably stronger east wind and cooler temperatures towards the late afternoon and evening as a high pressure entered the region from eastern Canada, bringing a cooler air mass along with it. This high pressure is also suppressing the coastal low pressure, which will drift south but overall remain nearly stalled off the coast of South Carolina. As ridging aloft over the region shifts east, the coastal low will begin to slowly return north, with slightly warmer temperatures for the early week as weak ridging builds in again ahead of a developing central US trough.
Mostly cloudy skies will continue tonight into Sunday morning, with a breezy NE wind around 10-15 mph, gradually decreasing. There is some slight uncertainty regarding how much cloud cover clears tomorrow; for tonight’s forecast, I am expecting partly cloudy skies by the afternoon and evening with highs in the mid 60s. Mostly sunny skies are expected for Monday and Tuesday with a continued light NE wind and highs in the upper 60s to low 70s. The next cold front will approach on Wednesday, which along with a southerly flow will pull moisture associated with the collapsed coastal low back north, with two areas of rain likely; one west of the area associated with the front, and another towards southeast New England and possibly eastern Long Island/CT with the moisture associated with the coastal low. The front is expected to end up near the East Coast on Thursday, but as the next section discusses, is likely to fail to quickly move through. The main question is how much rain reaches the area as opposed to staying east or west; at this time I included at least a 40% chance of showers, with the highest probabilities in eastern and western parts of the area, although especially with recent trends it would not be surprising if most of the rain stays away from the immediate NYC area.