December 2013 - Page 2 of 8 - New York Metro Weather

Tranquil weather will give way to weekend nor’easter

December 27, 2013/0 Comments/by John Homenuk

Colder, but more tranquil weather has settled into the forecast area to end the holiday week. After some light snow showers associated with a weak front and coastal system on Thursday, pleasant weather is expected on Friday and Saturday. Additionally, there will even be a bit of a warming trend both days, as high temperatures reach into the 40’s. The arctic air which stepped into the area earlier in the week won’t have any reinforcement until early next week, and so airmass modification will allow for temperatures to push warmer on both Friday and Saturday especially as the surface high pressure slips off the East Coast.

By Sunday, the weather becomes more active as a southern stream disturbance will slingshot up the coast. The system will ride on the eastern periphery of an incoming trough over the Central United States which, in its own right, will carry a ton of cold air with it. This means a few things, however. First, the system looks to be progressive despite its deepening off the coast. Second, the system will have plenty of warm air with it — and the cold air will have already modified out of the Northeast US. The aforementioned antecedent airmass won’t hold much potential for wintry precipitation. As such, the main concerns for this weekends system are a period of heavy rain and some gusty winds.

NAM model forecasting a coastal storm system on Sunday, providing the area with heavy rain.

Cold air, snow showers to close out the week

December 26, 2013/0 Comments/by John Homenuk

This holiday week has generally been characterized by the return of colder air (after quite a warm start from the tail end of the weekend) and chances for light snow. Much of the same will continue on Thursday, as temperatures in the 20’s to near 30 will be common during the afternoon and a weak disturbance passing through aloft will spark the development of snow showers throughout the area. The weak low pressure system forming offshore and the relative lack of moisture means that precipitation will be spotty at best — but nevertheless, some flakes should fly especially across New Jersey and much of the interior. Accumulations are expected to be extremely light.

Another cold night is expected from late Thursday into Friday, as the aforementioned developing low pressure system pulls down one more reinforcing shot of cold air. Low temperatures in the teens and 20’s should be rather common by early Friday morning. Despite the light snow over the past several days, the weather pattern has been generally quiet. But beginning with a storm system late this weekend, the activity looks to kick up once again as we make our way into January.

Northeast US surface analysis on December 26, 2013 showing a weak coastal low forming offshore.

Cold pattern looms for the first half of January

December 23, 2013/0 Comments/by Tom Stavola

As we approach the end of 2013, we close the books on a very wintry month of December for both the NYC metro area and the United States as a whole. From record lows across the Rockies, Plains, and Mid-west, frequent snow/ice events for the Northeast, a recent major ice storm for Northern New England, to record high temperatures yesterday over the region, this month has produced some wild swings in weather. Extreme temperature shifts were liable to occur this winter due to the presence of a negative EPO, blocking ridge in the North Pacific constantly combating an unfavorable positive NAO signal in the north Atlantic. The result has been a robust SE ridge, though the arctic air has been pressing quite fiercely on the NW fringes of this SE ridge. For our region, our location along the baroclinic zone / thermal gradient has yielded some minor to moderate snows for winter 2013-14 thus far, giving us above normal snowfall for December 2013. Some of the analogs previously examined for the winter outlook, like 2008, have been working well in terms of the overall 500mb pattern, although this month actually finished snowier than December 2008 for most. This is not a surprise since analog years won’t be able to tell us where the heaviest snow will fall, but they are helpful for clues for the mid level pattern that produces said wintry events.

Going forward, the pattern turns colder over the coming days, with an outside chance of a white Christmas for a low percentage of our area. A quick moving but fairly potent mid level wave will be propagating through the area tomorrow, and this could ignite some stronger snow showers in association with the zone of upward motion/convergence at 700-800mb. For most, it’ll bring about some “mood” flakes as a nice reminded that winter is still alive and kicking.

Dry weather prevails through late week, then things begin to get more interesting as we approach the New Year and beyond. The negative EPO, North Pacific ridge that provided us with the cold/snowy mid December briefly broke down over the past week (and we can see the result with very warm, rainy conditions) will be returning over the coming week. This NPAC mid level ridge has been a very stable feature over the past couple months and continues to be crucial in combatting the poor north atlantic / +NAO signal. However, the Arctic pattern could be changing over the next couple weeks, and this could make for a somewhat different evolution for January. Thus far, we’ve seen a strongly positive AO (low height field in the Arctic) which correlates to a stout SE ridge near the East Coast. That signal in conjunction with the +NAO has prevented the core of the cold anomalies from reaching the East Coast so far this winter.

Rain, fog continuing through Monday evening

December 23, 2013/0 Comments/by John Homenuk

Periods of rain, with continued spotty areas of dense fog, are expected to persist throughout the day on Monday. The culprit? A low pressure system riding northward up the coast along a frontal boundary. With plenty of moisture available, and warmer than normal air sitting along the coast and throughout much of the Mid Atlantic, widespread rain has developed essentially from the Southeast states into the Northeast US this morning. The rain will continue through much of Monday afternoon, with the areas of fog likely not lifting until later today.

Regional radar imagery this morning showed the bands of moderate to heavy rain continuing to stream up the East Coast. With time, however, the frontal boundary will begin to sag eastward and the heavier rain will follow suit. Cooler air is expected to move into the region by later tonight into Tuesday — as the 70 degree weather from Sunday will quickly become a distant memory. By Christmas day, we will be tracking the potential for bands of snow. More details after the break..

Regional radar imagery from Monday morning, showing areas of moderate to heavy rain moving up the East Coast.

Archive for month: December, 2013