Jan 11, 2013: Cloudy, Mild Weekend Ahead

Forecast Highlights:

Following today’s rain event, which has slightly exceeded expectations with 1/4 to 1/2 inch of rain across the area, a mainly cloudy and unseasonably mild weekend is expected, with temperatures peaking in the 50s, at least 15 to 25 degrees warmer than average. A cold front will move through on Monday, but temperatures will still remain above average through the rest of the week, with a wave of low pressure producing showers and possibly some snow on Tuesday and Wednesday.


Weekend – Monday: Unseasonably Mild, Mainly Cloudy

Starting with today’s rain event, widespread cloud cover will persist across the region through next Wednesday. A strong mid level ridge will remain in place over the region, with temperatures significantly warmer than average this weekend, peaking in the low to mid 50s for most of the area, in the upper 40s in parts of southern CT and the upper 50s in the immediate NYC area. Locations near and especially southwest of NYC may reach 60 degrees on Sunday. Both days will be mostly cloudy, with a risk of isolated showers on Sunday. These high temperatures are generally 20 degrees above average for the area. Overnight lows will also be mild, even warmer than the average high temperatures, with lows on Saturday night in the mid to upper 30s inland and upper 30s to mid 40s for the rest of the area. Sunday night will especially be mild with an approaching cold front, as temperatures struggle to drop below 45-50 degrees.

A cold front will move through the area on Monday; this front will be generally slow moving with a mostly dry frontal passage expected resulting in isolated to scattered showers throughout the day. High temperatures will peak early in the day in the mid to upper 40s west of NYC and the low to mid 50s from NYC and further east, slowly cooling down in the afternoon and especially into the overnight hours.

Tuesday – Wednesday: Cooler; Some Rain, Possibly Snow

Once the cold front moves offshore later on Monday, it will significantly slow down, and while temperatures will gradually cool down, there is no strong cold air mass behind the front, and temperatures still remain above average, but not nearly to the extent of this weekend. A weak wave of low pressure will develop on Tuesday, affecting the Mid Atlantic region with light to moderate precipitation. The model guidance varies with the specifics, although there is a consensus for this system to remain weak and somewhat suppressed. Currently, the 12z CMC model is the most bullish with widespread 8-10 inches of snow, but is a complete outlier compared to the rest of the models, and given its typically lower accuracy in this time range, was not used for tonight’s forecast. Currently, the GFS and ECM keep this mostly to the south of the area, with only isolated flurries or drizzle near and south of NYC, while the NAM has light snow, and the UKMET appears to resemble a less extreme version of the 12z CMC.

There remains some uncertainty with the Tuesday storm, although at this time it is not expected to become a significant storm. The current forecast is for showers on Monday night, which should mix with light snow especially north and west of NYC before ending on Tuesday. Should there be snow accumulations from this storm, they would remain minimal and focus north and west of NYC. Wednesday will be drier with partly sunny skies and highs in the low to mid 40s across most of the area.

Longer Range: Becoming Seasonable, And Then Colder

As yesterday’s pattern outlook mentioned, this mild pattern will not be long lasting; the pattern will gradually turn colder. This will not come instantly, however, and will take time to unfold. The polar vortex will drop towards the Hudson Bay by the late week, with a transient polar air mass clipping the northern parts of the region. NYC will remain far south enough for temperatures to remain close to average through the late week into the weekend, perhaps slightly above average, as temperatures moderate behind the first surge. After the 20-23rd, however, the potential may be there for a more widespread colder pattern. More information will be posted on this throughout the next week as details become clearer.

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