Sept 29, 2011: Cold Weekend, Chilly Week Ahead

NOTE: Tonight’s discussion was split into two parts. The first part of the forecast, discussing the outlook through this weekend, was posted tonight. A more detailed update on Saturday morning will discuss the weekend in more detail, as well as the outlook for next week into next weekend.


With the cut-off low that affected the region over the last week finally merging with another storm in Canada, a cold front moved through the area today, bringing widespread thunderstorms, some of them strong to severe, producing small hail and gusty winds. Over the last 2-3 days, rain totals ended up between 2-5 inches in NW NJ/SE NY, 1/2 to 1.5 inch in the immediate NYC area, and 1/4 to 1 inch across Long Island and southern Connecticut, according to the latest radar estimates.

As a second but dry cold front moves through the area tomorrow, warmer temperatures will return, with temperatures nearing 80 degrees in parts of the immediate NYC area. Behind this front, a significantly colder air mass will move in, keeping high temperatures below the 60 degree mark for Sunday while bringing the potential for light snow in the higher elevations of West Virginia, Pennsylvania and New York. Another Canadian trough moving into the Northeast next week will keep chilly temperatures in place through the middle of next week, but by next weekend, a large ridge from the central US will spread in, and may bring much warmer temperatures by next weekend.

Tomorrow’s Outlook:

Even though a cold front moved through the area today, another front to our west will be the one that will push the warmth out. This front will move through the area on Friday night, which will bring warmer temperatures into the area for Friday. With 850 mb temperatures near 11-12 degrees celsius along with partly sunny skies and a SW/SSW wind, temperatures tomorrow will be warmer, reaching the mid 70s inland, upper 70s to 80 degrees in the immediate NYC area, and the mid to upper 70s in Long Island and southern Connecticut.

Weekend Outlook: Cloudy, Chilly, Rainy

Behind the cold front tomorrow night, a significantly colder air mass will move into the region from Canada, with a large area of 850 mb temperatures below zero degrees celsius. Unlike what was modeled several days ago, however, the cold will not be able to pour straight into the area. Last night’s update mentioned that a low pressure was expected to develop near New Jersey on Saturday, moving into New England on Sunday, due to an upper level low over the region. The latest trends have placed this upper level low further southwest with a stronger surface low, which will result in a stronger low pressure tracking over the area, keeping the cold locked to the SW of the area while bringing warmer temperatures northeast of NYC.

The latest outlook for this weekend is for rain to develop across the area after 12 AM Friday night. Light to moderate rain will continue through at least Saturday morning, with mostly cloudy to cloudy skies and scattered showers lasting through Sunday as the low pressure moves over NYC. Due to the position of the storm, temperatures will be the coldest further west and the warmest further east, with high temperatures on Sunday expected to reach the lower to mid 50s in NW NJ/SE NY, mid to upper 50s in the immediate NYC area, and the lower 60s in most of Long Island and southern Connecticut. Due to the cloud cover and the location of the low pressure, temperatures on Sunday night will not be as cold as previously thought, staying in the 40s across most of, if not the entire area. The lowest temperatures will be in the upper 30s to lower 40s in NW NJ/SE NY. Temperatures will slightly warm up for Monday, reaching the mid 50s to lower 60s across the area.

Longer Range: A more detailed, longer discussion will be posted on Saturday morning, discussing the latest expectation for this weekend as well as an update on the Northeast snow potential. The main focus of the discussion, however, will be on next week into next weekend, as a second cool down in the middle of next week may be followed by a significant warm spell by next weekend. More information on that, as well as the potential scenarios, will be posted on Saturday morning.

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