Jan 16, 2013: Winter Pattern Getting Started

Forecast Highlights:

Following last night's winter storm which affected the area with snow, sleet and freezing rain north/west of NYC and mostly rain for NYC and south/east, temperatures will slightly warm up on Thursday, with a storm staying mostly south of the area before colder temps return on Friday. After a brief warm up this weekend, a much colder pattern is expected for next week.

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Today's Storm Review:

The first winter storm since December 29th affected the area last night and earlier today with a variety of impacts across the area. Some sleet mixed in with the rain in NYC and further south/east, but for the main part precipitation type stayed as rain. North and west of NYC, a more wintry scenario unfolded last night; locations generally close to the I-80 corridor, up through parts of NE NJ, far southeastern NY and southern CT observed sleet and freezing rain, mixing with snow at times, with up to an inch of snow. There was a relatively sharp gradient between the sleet area and the primarily snow zone further north in north central-NW NJ, SE NY and interior southern CT, where at least 3 to 5 inches of snow were observed. Most of the area switched over to light rain showers by the late morning and early afternoon, including interior parts of the area that stayed with mostly snow during the main part of the event.


Tonight - Friday: Warmer, Then Much Colder; Storm Stays South

Partly cloudy skies are expected for Thursday, with highs reaching the low to mid 40s across the area. Attention over the last day has been fixed on a storm for Thursday night; this was originally modeled to stay well to the south, with precipitation barely extending north of the North Carolina-Virginia border, but last night's update mentioned this could still change and end up more north. Today's model guidance has trended north with the storm, some models significantly north, far enough to even show light accumulating snow in NYC. Despite this event only 24 hours away, the model guidance yet again has failed to settle on a consensus throughout the day. The north trend, however, has stopped for the main part, with some of the northernmost models such as the GFS having trended south this evening.

The storm tomorrow night will affect the southern and central Mid Atlantic, but will end up sliding east before reaching the area as a cold front crosses the region. Most of the precipitation will stay south of the area, with the potential for a moderate snowstorm over parts of Virginia and the Delmarva Peninsula. Mostly cloudy skies are expected on Thursday evening into the early overnight hours, with light snow showers mostly in Long Island and south of central New Jersey. Any accumulations in Long Island will be minor and generally staying further east. Flurries may reach NYC, although no accumulations are expected. Skies will clear overnight with lows dropping into the low to mid 20s inland and mid to upper 20s for the rest of the area, with lows near 30 in NYC, with much colder temperatures on Friday, peaking in the low 30s inland and low to mid 30s for the rest of the area, possibly staying below 30 degrees for some interior areas; highs on Friday will generally be at least 5 degrees below average.


Next Weekend - Next Week: Much Colder Pattern Expected

Friday night will be cold again, with lows similar to those of Thursday night; despite these temperatures being colder relative to what has been observed so far this season, these are still slightly warmer than average. A weak low pressure will track towards the US-Canada border, with a southwest flow developing for Saturday with partly sunny skies and highs peaking in the upper 30s to mid 40s across the area. A dry cold front will move through the area on Sunday; while highs will still be on the warmer side, slightly cooler than those of Saturday, this front will bring a cold pattern into the region for the first time since January 2011.

The mean trough will end up over the Northeast and north central US in this time frame with persistent ridging in the western US. This arctic air mass is not close in intensity to other, more extreme arctic outbreaks such as January 1994, or January 2004 when Central Park dropped to 1 degree, although this is still significant considering there has not been such a cold pattern in two years, with temperatures generally staying below average. Highs are mostly expected to be in the 20s next week, with lows in the 10s for most areas and possibly in the single digits inland on a few occasions. A few weak clipper systems are likely next week, with increased cloud cover on some days along with scattered snow showers, which would prevent much colder overnight lows on some days; at this time, light snow may be possible on Tuesday and/or Wednesday. Stay tuned for more information on next week's pattern.