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Significant storm will bring rain, wind through Thursday

If you are a fan of changeable weather, today is for you. A major storm system, developing as a result of a mid level phase, will organize over the Tennessee Valley and shift northeastward to a position near New York City late tonight. The track will mean significant winter weather for our friends in Northern New England (including many of the major ski resorts), but more notably one of the more dramatic swings in sensible weather our area has seen in months. Temperatures will swing from the mid 60s to 70s in some spots this afternoon, all the way down into the 20s by Thursday morning.

Not surprisingly, the significant storm system moving through the Northeast US Wednesday into Thursday will feature a powerful thermal gradient and cold front. Initially, the thermal gradient will develop along a warm front which will stretch from southwest to northeast through the Northeast Wednesday afternoon. Parts of New Jersey could eclipse 70 degrees as southerly winds increase and temperatures increase in the low levels. Forecast models show drizzle and rain eventually increasing in coverage and intensity by Wednesday evening as moisture and lift begin to increase and the frontal boundary approaches Central Pennsylvania.

Regional radar imagery showing precipitation approaching the area (weather tap).

Regional radar imagery showing precipitation approaching the area as of 9:15am (weather tap).

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Warmup, rain ahead of impressive cold front

Fair weather and warming temperatures will be the story on Tuesday, as westerly winds continue and temperatures warm up aloft. Highs on Monday, which reached into the 50’s, will be bested by the early afternoon hours through much of the area. The warmest temperature readings are likely to come from Southern and Central NJ, where short term forecast models show some potential for temperatures to reach into the upper 60’s by afternoon with abundant sunshine. Despite being a few degrees cooler, areas farther north will also be feeling the warmth especially compared to what the past several weeks have had to offer.

The warmth will feel a bit more muggy by Wednesday, as a storm system approaches the area from the Tennessee Valley and eventually tracks fairly close to the area by later Wednesday. Drizzle and increasing clouds will put a damper on what otherwise will be another warmer than normal day, especially south of a warm front which is forecast to position itself from west to east in Central New Jersey. Rain will become more steady later in the day on Wednesday and may actually become heavy for a period of time late Wednesday night.

HRRR model forecasting high temperatures in the mid 60's in parts of the area Tuesday afternoon.

HRRR model forecasting high temperatures in the mid 60’s in parts of the area Tuesday afternoon.

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Midweek storm trending more wet than white

It has been a while since we have been able to confidently back off on winter weather potential; in a season which has featured an absolutely tremendous amount of snowfall events and a staggering amount of over-performers. With the upcoming midweek storm, the winter weather potential was fairly clear from the get go. A southern stream disturbance meandering near the Mississippi River, some cold air in place to start, and an energetic northern stream disturbance racing southeastward from Canada to the Great Lakes. The summation of all of these parts usually results in a winter weather event somewhere in the Northeast US, and this situation likely will end no differently. But a delicate evolution of events is likely to produce a warmer situation in our local area.

The evolution of the system begins well to our west, over the Rockies and International Border in the Northern US. As mentioned earlier, a southern stream disturbance will eject from Mexico into the Southern United States (likely providing a fairly significant amount of moisture) while a disturbance from the northern stream slides southeastward to phase with it. At the time of the interaction, a lack of high latitude blocking (over the Northwest Atlantic and Greenland) will allow for height rises over the East Coast, and warmer air intrusion ahead of the developing system. This will be less of a concern over New England, but all models agree that the warm air will likely warm both the mid levels and the surface and help to keep the thermal gradient to our north — meaning more rain than snow in much of the area.

GFS model showing a low pressure system tracking very close to the area on Wednesday afternoon.

GFS model showing a low pressure system tracking very close to the area on Wednesday afternoon.

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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..