You just lived through one of the snowiest periods in NYC’s history

Sounds dramatic. The response to the title of this article, from some, will likely be: “Well,  obviously.” But when you take a second to consider that we actually did live through one of the snowiest periods in the history of observed weather at New York City, it becomes fairly remarkable. The past 30 days or so have been nothing short of anomalous, with colder than normal temperatures (including a visit from an unusually impressive Polar Vortex) and well above normal snowfall throughout a vast majority of the forecast area.

The statistics don’t only confirm what we’ve known all along, they bring to the surface the reality of just how impressive the past month or so has actually been. The entire winter, in a certain sense, has been a giant anomaly — and it has been relentless. Things came to a bit of a head over the last 30 days, however, and our stats will focus on just how impressive the past month or so has actually been.

Snowfall by season in NYC, including 2013-2014 to date. Image courtesy Yehuda Hyman.

Snowfall by season in NYC, including 2013-2014 to date. Image courtesy Yehuda Hyman.

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Historically snowy pattern set to take a hiatus

Many have longed to hear it: There is no snow in the short or medium range forecast. The historically cold and snowy pattern which had gripped the area over the past several weeks, dating back to the middle of January, will finally take a respite during the upcoming week. It wasn’t without a bit of dramatic flair that it will do so, still, with two small snow events simply nudging up the seasonal snowfall totals right before the warmup begins. We’ll have an article out within the next few days where we’ll talk numbers: Stats, information, and data regarding the past month or so — and just how staggering some of the snowfall numbers really are.

But for now, our attention will turn to a pattern change which is coming during this week and starting as early as today. If you haven’t felt it yet, warm sun has brought temperatures in the lower 40’s throughout the area behind the storm system which dropped a few inches of snow on the area this morning. The warmup will become even more noticeable as the week draws on, with a period of rain likely on Wednesday and then temperatures in the 40’s and 50’s from Thursday into Friday.

NAM model forecasting temperatures in the 50's ahead of a cold front on Friday.

NAM model forecasting temperatures in the 50’s ahead of a cold front on Friday.

Interestingly, and probably not surprisingly to most, the rapid change in weather can and likely will cause problems which aren’t related to any precipitation. We begin with things like snowmelt, flooding and fog — and end on Friday with the potential for gusty winds in thunderstorms and heavy rain. Wednesday’s periods of rain will be the initial hit to the snowpack which is bordering on historic throughout much of the area, especially the interior where some still retain over 20″ of snow depth.

After periods of rain on Wednesday, the warmup and east/southeast winds on Thursday into Friday will allow for increasing fog throughout the area. Snowpack suffers greatly during thick or dense fog, so we should continue to see melting snow. If you have blocked drains, or areas that are susceptible to flooding from melting snow or rapidly increasing water levels, now would be a good time to deal with those areas in advance of the expected snow melt.

Much of this pattern change, however brief it may be (we’ll get to that in another post), is being driven by a significant low pressure system moving through the North-Central United States during the middle to latter part of this week. This low pressure system is being fueled by a significant trough in the mid and upper levels of the atmosphere, which will dig through the southwest states and then northward into the Great Lakes. As you could image, the result of all of this will be a fairly significant Southeast Ridge — and warmer than normal temperatures pumping northward toward our area.

Storm Prediction Center extended outlook from 2/18/14, showing a risk extending into parts of NJ on Friday.

Storm Prediction Center extended outlook from 2/18/14, showing a risk extending into parts of NJ on Friday.

Ahead of the cold front on Friday, temperatures will rise into the 50’s despite meeting some significant resistance from the snow pack and trapped low level cold air. As the front moves through, showers and some embedded storms are expected, owing to lots of energy aloft and plenty of lift for heavy precipitation. The storms could border on strong levels given the impressive wind speeds aloft — and the Storm Prediction Center has noticed, placing parts of Southern NJ in a risk for severe thunderstorms on Friday.

After Friday, the warm air will be kicked out once again. And forecast models are hinting at ‘Ol Man Winter waking up from his quick nap, only to return more ferociously than before. Enjoy the warm weather..

Light to moderate snowfall likely Tuesday

After going a whole 12 to 24 hours without the area seeing snow, snow will finally be making its return to the region for late tonight and through tomorrow morning, ending the prolonged snow drought.

Kidding aside, there will be a potent mid-level wave traversing the Midwest and Great Lakes throughout this evening, leading to moisture developing out ahead of it into our relatively chilly airmass. Not surprisingly, there is a battle between the higher resolution mesoscale models (NAM, ARW, RGEM, RPM) showing more precipitation, and the global models (GFS, and Euro) showing less precipitation. Nonetheless, however, today’s data has indicated a slight upward tick in precipitation across the region, which may allow some of us to receive a bit more snow than initially thought.

Today's 12z RGEM (short-term Canadian model) shows a storm system running into a departing surface high pressure system, leading to snow for many areas, with mixing along the immediate coast.

Today’s 12z RGEM (short-term Canadian model) shows a storm system running into a departing surface high pressure system, leading to snow for many areas, with mixing along the immediate coast.

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One storm exits, another approaches by Saturday

A few weeks ago, we posted that from late January onward our area was likely to receive a very wintry period of weather; cold air, chances for snow. Now that we’ve made it to mid February, most of the area has experienced several significant snowfall events and has experienced the brunt of below normal temperature anomalies.

And we’re not done just yet.

Forecast models have come into agreement on the development of a storm system off the East Coast on Saturday, and although it may not be as strong as the one which passed nearby on Thursday, there is likely to be more precipitation from the system as it strengthens off the New England Coast. The key to forecasting this one, as is the case with many, will be timing how fast the rapid strengthening of the system begins. This will have a major impact on whether or not our area sees bands of heavier snow, or a more broad area of lighter snow.

NAM model showing the development of a Nor'Easter on Saturday.

NAM model showing the development of a Nor’Easter on Saturday.

 

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