After a dry half month period, with unseasonable warmth observed over the last few days, a cooler and somewhat rainier pattern returns to the region starting with a strong cold front on Monday that removes the warm air mass with 1/2 to 1 inch of rain likely, followed by a cooler second half of the week as highs return into the 60s to mid 70s with another possibility of rain by the late week.
[notice]Blog Note: I was unable to fully update the blog over the last 2 days. Daily updates will resume starting today, and the 2-week pattern outlook is currently scheduled for Monday.[/notice]
Today – Monday: Rain Returns Monday Night
Following the unexpected significant warmth on Friday with widespread mid to upper 80s observed, and even a 90 degree reading in Teterboro, NJ, the outlook was for a frontal boundary to sink southwards and settle near or just north/east of NYC, but with uncertainty in the exact position of the boundary. Yesterday, the frontal boundary ended up shifting south of NYC, and currently remains stalled near central-northern NJ close to the I-80 boundary, keeping most of the area under an easterly wind with cloudy skies, fog and drizzle. These conditions are expected to continue today with high temperatures struggling to warm up beyond the low to mid 70s.
The storm that produced a major early season blizzard and severe weather outbreak in the Midwest remains a strong upper level low cut off from the jet stream, currently over Iowa and slowly moving to the northeast, with a strong cold front extending south through the Ohio Valley into the Gulf of Mexico coast. The remnants of tropical Depression Karen, which dissipated off the coast of Louisiana this morning, are located near the southern end of the cold front, with some tropical moisture pulled north along the front to result in locally heavy rain. The trough, however, will be quickly pulled north by a strong Canadian trough, with the front speeding up as it tracks through the northeast US while slowing down further south in the southeast US. As a result, the trough will fail to pull Karen’s remnant low up the coast, which will continue to slowly drift northeast through the SE US and will have an impact on the late week outlook for the area, although locally heavy rainfall is expected along the frontal boundary with precipitable water values approaching 2 inches.
For Monday, mostly cloudy skies are expected for the first half of the day along with a risk of isolated showers, with warmer temperatures than today as the warm front shifts north and a breezy south wind develops at 10-20 mph with gusts up to 30-40 mph, with highs rising into the low to mid 70s east of NYC and mid to upper 70s from NYC and further west. By 4-6 PM, a line of heavy rain and some thunder is expected to reach NYC, which will continue to progress east into Long Island and CT by 6-9 PM while weakening, with a quick drop in temperatures from the 70s to the upper 50s-low 60s. Rain is expected to end towards 12-3 AM as the front exits to the east, with at least 1/4 to 3/4 inch of rain east of NYC, and 1/2 to 1.25 inch from NYC and further west, locally higher.
Tuesday – Friday: Cooler; Rain Possible
As the strong upper level low lifts north into Canada, another strong upper level low is expected to dive into the western US, resulting in amplifying ridging to its east. With Karen’s remnants stalled off the southeast US coast, however, ridging will be displaced north of the region as lower heights aloft persist overhead, with a surface high pressure stationed to the north of the area. With troughing sustained in the western US and the jet stream mostly staying well to the north, this setup is expected to persist until at least next weekend. South of the ridging in the US/Canada border, a low pressure is expected to organize off the eastern US coast and slowly approach the region before stalling; the main uncertainty in the outlook is regarding how far north this low pressure reaches, with the latest models bringing it north with rain affecting the area at least between Thursday and Saturday.
Tuesday and Wednesday are expected to be mostly sunny with highs in the mid to upper 60s and a light north/NE wind, with overnight lows in the 40s away from NYC and the immediate coast. Towards the late week and weekend, confidence decreases depending on how far north the low pressure ends up; at this time, the forecast is for increased cloud cover and a slight risk of showers south of NYC for Thursday and Friday with temperatures slowly warming up to the upper 60s to possibly mid 70s range, although this is subject to change. Stay tuned for more information on next week’s outlook.