Jan 5, 2011: Tracking Two Snowstorm Potentials


***This post is from 2011. Please visit the MAIN PAGE to see the latest forecasts for January 2012.

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Notes:

– NYC Area Weather issued a Light Snow Alert and a Snow Watch for the area, please refer to the “Weather Alerts” page for the latest alert in your area.

– The poll for Friday’s storm will end tomorrow evening, please vote if you have not done so yet. The current majority is for the solution where heavy snow affects NYC, with 8 out of 16 votes.

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Today was a partly sunny day across the area, with high temperatures close to the forecast but slightly warmer in some spots, in the upper 30s to lower 40s across the area. Temperatures will continue to slightly cool down over the next few days until Friday, when a storm staying to the south of the area will bring an inverted trough that may potentially affect parts of the area with locally heavy snow. This is not the only storm potential in the coming week, however, as there is also the possibility of yet another snowstorm to affect the region around the middle of next week.

Tomorrow’s Outlook:

Tomorrow will be a mostly cloudy to cloudy day across the area, as clouds spread from the west due to a storm that will affect the area on Friday. High temperatures will be in the lower to mid 30s inland, likely towards the higher end of that range with a few upper 30s possible in the warmer case scenario, and in the mid to upper 30s for the rest of the area. As with today, a few lower 40s cannot be ruled out. A light WSW wind is expected.

Friday – Saturday: Uncertainty With Heavy Snow Band

As mentioned yesterday, the models showed the coastal low well to the east of the area, with an inverted trough being the snow producer for the area. Today’s models have remained consisent with this solution, and this is the expectation for this storm. With every model showing at least some snow for the area, and the set up supporting this, it is no longer a question of if snow falls, but rather how much snow falls. With such a set up, however, it is difficult to locate the exact places that will be affected by the inverted trough, which will likely feature a heavy snow band stalling over some places, though there is the potential for this to happen in the central and eastern parts of the area.

This morning’s models suggested this could be over New York City and NE NJ, with the NAM and GFS showing as much as a foot of snow, however have since trended northeast to focus the inverted trough over central/western Long Island, south central and southwestern CT, and southeastern New York. Due to the large spread, I put at this time a Snow Watch for the central and most of the eastern parts of the area for the potential of 2-5 inches of snow, locally as high as 10-14 inches, with a light snow alert for the western parts of the area, however this is subject to change.

Forecast for the NYC area: On Friday morning, light snow should spread across the area from west to east. At least a period of moderate snow is likely across the area as snow intensifies by the afternoon hours, however accumulations through then should be light, with up to 2 inches by the mid afternoon hours. By the evening hours, however, uncertainty comes in as the inverted trough appears to stall somewhere. The latest expectation for this is to happen somewhere around central/western Long Island, SW Connecticut, potentially extreme northern New Jersey, and southeastern New York, but it could shift around further east or west. Where the inverted trough stalls, heavy snow will develop and stay stationary, with amounts locally reaching or even possibly exceeding 10-14 inches in the places hit the hardest by the inverted trough. That area will be narrow, however, and most areas will just see light to moderate snow with perhaps an additional 1-3 inches at most. The snow will then become lighter in the late overnight hours and end by Saturday morning.

The snow will start out first with temperatures near freezing, leading to more of a wet snow with snow to liquid ratios less than 10:1, but as temperatures drop by the evening, the area should change over to a colder, high ratio snowfall, which will help lead to the high snow totals where the inverted trough sets up.

This is a complicated set up, and it may come down to tomorrow or perhaps even the morning of the day of the storm when we know for sure where the inverted trough sets up, as the models are having difficulties handling this feature. While for most, this will only be a light to moderate snow event with a general 1 to 3 inches of snow, isolated areas could end up with as much as near or even over foot of snow, potentially in the central or eastern parts of the area. Stay tuned for more information on this storm tomorrow along with a snow map.

Longer Range: Cold, Then Another Storm Potential

Colder temperatures will return on Saturday, with high temperatures only in the mid 20s to lower 30s across the area. While temperatures will start a slow warming trend by Sunday, they will remain below average, only in the upper 20s to mid 30s. By Monday, high temperatures will reach the lower to potentially upper 30s, however another storm could bring an end to the quiet conditions.

By now, it is certain that we will be seeing some type of storm in the East Coast around this time frame, but the latest models have trended much more southeast, now keeping the snow south of the area. While it is too early to nail down the exact track, the inland track is becoming less likely, and it appears that we may be dealing with the same question for this storm that we have had with most of the storms over the last month: whether the storm affects the area with snow or stays out to sea. An inland track cannot be ruled out, but it’s not a very likely option at this time. Some models are showing potential for this to be a big snow maker either near or south of the area, and while these details will change around over the next few days, a storm is expected to affect the East Coast during this time frame, and may affect the NYC area between Tuesday and Wednesday. Stay tuned for more information on this storm and how it may affect the area.

The latest models continue to show the potential for a major arctic cold outbreak across the north central and eastern United States around the third week of January along with the potential for a storm sometime between January 16 and 20, and while these potentials are still too far out in the long range to be discussed in more details, I will continue to watch these potentials and will discuss them in more information once details become clearer.

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