Friday, February 10, 2012

Feb 10, 2012: Light Rain/Snow Tonight


Cloud cover gradually increased across the area today with temperatures peaking in the 40s. With an approaching storm, cloud cover has increased today with cloudy skies currently observed across the area. Although the expectation is for some light snow to fall out of this, the latest observations signal that despite yesterday's scaled down forecast, there could be even less snow than expected out of this storm.


Tonight - Tomorrow: Generally Up To 1", Locally 2-3"


Last night's update mentioned that one of the uncertainties with the storm was regarding whether it would develop closer to the coast or further offshore, with the offshore scenario the more likely solution. Today's model guidance settled on the offshore scenario, with the low pressure expected to develop well offshore. There is already light precipitation across the region, falling as snow away from the coast and light rain closer to the coast, although temperatures will gradually cool down tonight, allowing for a changeover to light snow in NYC by at least 1-2 AM and further southeast after 2 AM. By that time, widespread light snow will fall from NYC and north/west, but will have trouble sticking and accumulating due to the marginal surface temperatures, still in the lower 30s away from NYC and the mid 30s closer to NYC.

The development of the coastal low will take place too far offshore for the region to get any large precipitation amounts, and as a result, only light precipitation is expected to affect the area through tomorrow afternoon. Light snow, mixing with rain at times in Long Island, will continue to fall through at least 12 PM, with the snow in southern Connecticut and eastern Long Island sticking around a little longer. During the whole event, it will be difficult for the snow to accumulate due to marginal temperatures, and as a result, accumulations will likely be lower than the average 10:1 snow to liquid ratio.


Forecast For Area: Overall, the final storm forecast has been downgraded from yesterday's update, with up to 1 inch of snow expected north and west of NYC and in NYC itself, locally up to 2 inches especially north and NE of NYC. Long Island will likely see up to an inch, with northern parts of Long Island potentially getting closer to 1.5 or 2 inches, with southern Connecticut, especially further east, seeing at least 1 to 3 inches of snow. With the lowered accumulations, I removed the Light Snow Alert for the entire area except for southeastern CT, which has the best chance of seeing 2-3 inches of snow across the area.

To the left, I posted a snow map for this storm. Due to the uncertainty, this snow map only has medium confidence, and parts of the map are still uncertain. Although NYC is within the 1-2 inch range on the map, lower accumulations are expected, and I placed text to show accumulations near 1 inch in the NYC area, locally lower or higher, although accumulations in NYC itself at this time are more likely to end up below 1 inch. The biggest uncertainty with the map is regarding the accumulations in the immediate NYC area, as well as accumulations in Long Island, where uncertainty with the rain/snow line may make the difference between a coating of snow and accumulations near 2 inches. Stay tuned for storm updates tomorrow morning.


Longer Range: Cold temperatures will briefly return for this weekend, with high temperatures reaching the upper 20s to lower 30s across most of the area on Sunday along with windy conditions and partly sunny skies. Temperatures will warm back up into the 40s for next week, excluding Monday which will likely bring temperatures into the upper 30s, although a weak low pressure will move through the region on Tuesday into Tuesday night, bringing a risk of isolated snow showers across the area. Another storm may be possible towards the end of next week into next weekend, although at this time the probability of a significant storm appears low. Stay tuned for more information on the longer range.

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