One thing a snow lover in the central and eastern US is rooting for during the wintertime is a “high-latitude blocking” pattern in the upper part of the atmosphere as it is often favorable for sustained cold air outbreaks and potentially accumulating snow. One way meteorologists can monitor the likelihood for this type of weather pattern is to track a teleconnection index known as the North Atlantic Oscillation (NAO). If this index falls into “negative” territory for a sustained period of time during the wintertime – a snow lover’s dream – it is often associated with sustained colder-than-normal weather in the eastern and central US and an increased chance for accumulating snow. Here we are now into the month of April and the largely absent “-NAO” pattern this winter season has finally arrived with “high-latitude blocking” likely for the next week or two across the northern latitudes. This may not lead to snow this time of year – although stranger things have happened – but it does signal the likely continuation of cold air outbreaks into the central and eastern US through at least the middle of April.
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Low pressure will push off the Carolina coastline later tonight and make a move to the northeast out over the open waters of the western Atlantic. It will not, however, continue in this direction for too long before it encounters a blocking pattern in the upper part of the atmosphere which will lead to an unusual movement in coming days as it will retrograde back towards the Northeast US. This low pressure system is producing rainfall today across the southern Mid-Atlantic and then, as it retrogrades back around late this week, it could swing a band of clouds and showers from northeast-to-southwest through the Northeast US and into the Mid-Atlantic region.
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The active weather pattern that we have been experiencing across much of the nation in recent days will continue at least into the middle of next week. Low pressure over the middle of the nation this weekend will keep much of the eastern half of the nation unsettled and there are signs that a significant storm may form by the middle of next week. The potential is there for a strong storm to develop next week in the south-central US and then head northeast towards the Mid-Atlantic region and it could have a wide-ranging impact on a large part of the eastern third of the nation.
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Multiple storms will track across the country over the next several days bringing significant rainfall to much of the eastern half of the nation, substantial snowfall to higher elevation locations across interior New York State and New England, and severe weather to the Deep South, Tennessee and Ohio Valleys. This active weather pattern is partly the result of continuing cold air outbreaks into the central and eastern US which will very likely persist right into early April. The first storm of a series of upcoming storms is currently bringing heavy rainfall to portions of the Mid-Atlantic region and Northeast US and also accumulating snow to higher elevation interior sections of New York State and New England. A second storm will bring more significant rainfall to the Mid-Atlantic region later Tuesday night into Wednesday and there can be snow on the northern edges of this next storm system. By the end of the week and early weekend, low pressure will intensify over the nation’s midsection and a frontal boundary zone will extend from the low pressure center to the Mid-Atlantic region. The combination of the low and frontal system will produce more unsettled weather conditions on Friday, Saturday and Sunday in much of the eastern half of the nation.
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Unseasonably warm weather on Friday in the Mid-Atlantic region gave way to a much colder weekend following the passage of a strong cold frontal system. The cold air mass in place today across the Mid-Atlantic region and Northeast US is being anchored by a strong, cold high pressure now situated over the southeastern part of Canada. Moisture will advance northeastward later tonight towards the Mid-Atlantic region and our entrenched cold air mass will be reluctant to give up its ground as high pressure slides toward the Canadian Maritimes. As a result, there is the chance for snow or a mix of rain and snow in much of the northern Mid-Atlantic region later tonight into early Monday with significant snow possible across interior, higher elevations of upstate PA, New York and New England.
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Unseasonably warm weather dominates the scene today in much of the Mid-Atlantic region with temperatures at mid-day ranging from the 70’s in DC to the 60’s in Philly while stubborn cool air is hanging on in NYC with temperatures in the 50’s. A strong cold front is closing in on the eastern states at this hour and will produce afternoon and evening showers and perhaps a strong-to-severe thunderstorm or two. Following the passage of the strong cold front later tonight, the weekend will become progressively colder as strong high pressure builds into southeastern Canada. By the end of the weekend, moisture will be advancing northeastward towards the Mid-Atlantic region and our entrenched cold air mass will be reluctant to give up its ground as high pressure slides toward the Canadian Maritimes. As a result, there is the chance for some snow or a mix of rain and snow in at least parts of the DC-to-Philly-to-NYC corridor from later Sunday night into early Monday with significant snow possible across interior, higher elevations of the Mid-Atlantic and NE US.
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Tomorrow may turn out to be the warmest day so far this season in the Mid-Atlantic region with temperatures soaring to the 70’s in the DC-to-Philly-to-NYC corridor ahead of a strong cold frontal system. In addition, there will be occasional showers; especially, during the afternoon and evening hours and perhaps a strong-to-severe thunderstorm or two mixed in as well. Following the passage of the strong cold front late Friday night, the weekend will become progressively colder as strong high pressure builds into southeastern Canada. By the end of the weekend, moisture will be advancing northeastward towards the Mid-Atlantic region from the Tennessee Valley and our entrenched cold air mass will be reluctant to give up its ground. As a result, there is the chance for some snow or a mix of rain and snow in at least parts of the Mid-Atlantic region early next week and significant snowfall may fall across upstate New York and New England.
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An active weather pattern continues across the nation and this will lead to more chances of rain for the Mid-Atlantic region and also quite a topsy-turvy temperature pattern. In fact, temperatures could climb well up into the 70’s on Friday in at least parts of the Mid-Atlantic region ahead of a strong cold frontal system. That cold front will usher in progressively colder air for the weekend and there is actually a chance for some snow early next week in the Mid-Atlantic region as moisture is likely to advance to the northeast and into a cold air mass that will be slow to retreat.
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Explosive intensification is about to take place with an ocean storm now over the western Atlantic. A strong “clipper” system is moving into the Mid-Atlantic region and it is interacting with the upper-level energy that remains from the ocean storm which soaked the southern US earlier in the week. This interaction will result in a drop of central pressure of the ocean storm from around 992 millibars (29.29 inches) at the current time to around 965 millibars (28.50 inches) by the middle of tonight. While this ocean storm is situated well off the east coast, it is still going to influence the Mid-Atlantic region late today and tonight as an inverted trough (aka “norlun” trough) is forming from the center of the low pressure system northwestward to the Mid-Atlantic. As a result, there are rain showers this afternoon throughout the Mid-Atlantic region and even a few embedded thunderstorms. However, as colder air aloft becomes wrapped up into the overall system, a mixing with and changeover to snow is possible later today or early tonight in many spots and there can even be some grassy accumulations; especially, in higher elevation suburban locations.
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A strong “clipper” system will drop southeastward into the Mid-Atlantic region on Friday and it’ll feature some rather cold air in the upper part of the atmosphere. At the same time, the southern storm that continues today to produce significant rainfall in the SE US will intensify after it moves out over the open waters of the western Atlantic. In fact, this storm could intensify to a point where it is produces hurricane-force winds by tomorrow night in the western Atlantic. While this ocean storm will be situated well off the east coast, it’ll still have an influence in the Mid-Atlantic region as an inverted trough (aka “norlun” trough) will extend from the low pressure center all the way back to the Mid-Atlantic. The combination of the “clipper” system in the northern stream and the inverted trough associated with the ocean storm is likely to lead to rain and/or snow showers in the Mid-Atlantic later tomorrow and tomorrow night. In some “norlun” trough cases, small-scale heavier precipitation bands can develop and we’ll have to closely monitor that possibility late tomorrow and tomorrow night.
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