Feb 25, 2011: More Rain, Wind On Monday

Feb 26 Morning: So far this winter, most of the storms ended up changing with last minute trends in the short range on the models, and Monday’s storm seems to be no exception, as the latest 12z NAM run takes the low pressure directly over the area instead of the western Northeast, and the GFS brings this storm in two waves, one of them mainly to the north of the area and the other one to the south of the area. With the current uncertainty, the next update will be posted tonight after I review this afternoon’s model runs to determine what changes, if any, should be made to the forecast.

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Today, the area saw a widespread heavy rain event as a low pressure tracked over the immediate NYC area. In addition, windy conditions were observed in Long Island and parts of the immediate NYC area and southern Connecticut, with winds gusting up to nearly 60 mph in parts of Long Island, and in the early afternoon, a line of strong thunderstorms moved through parts of the immediate NYC area extending further southwest into Delaware. With the storm out of the region, windy conditions will begin to end, with light winds expected by tomorrow morning.

Much colder temperatures are expected tomorrow in places that were in the warm sector of the storm today, including Long Island, parts of southern Connecticut and New York City, with a weak storm bringing light rain/snow from NYC and further north on Sunday morning, however the set up will quickly change overnight, with heavy rain and thunderstorms expected for Monday evening/night as temperatures approach the 60 degree mark in parts of the area.

Tomorrow’s Outlook:

Tomorrow will bring drier conditions to the area, with partly sunny skies in the morning and increasing clouds in the afternoon as the next storm approaches. High temperatures will be in the mid to upper 30s for most of the area, with upper 30s to lower 40s in the immediate NYC area. A northwest turning southwest wind is expected.

Sunday: Light Snow Expected

On Saturday night, cloud cover will increase ahead of a weak disturbance moving from west to east towards the Northeast. The NAM model earlier today continued to suggest that this would be far south enough to bring several inches of snow to the area, though the rest of the models are further north, and the NAM also adjusted north with its latest run once again, bringing 2 to 4 inches of snow from central New York into southwestern Maine.

Despite most of the precipitation staying to the north of the area, as there will be enough cold, light snow is expected to fall from New York City and further north during Sunday morning, which may accumulate up to 2 inches well north of NYC. The snow will mix with and change over to rain in the southern and eastern parts of the area, including Long Island and New York City, though the northwestern parts of the area may stay with plain snow until the storm ends in the late morning. Behind the storm, some clearing in the cloud cover is expected with high temperatures rising into the lower to upper 40s across the area.

Monday: Storm To Bring Rain, Thunderstorms, Wind

Between Sunday and Monday, the set up will go from one extreme to another, with Sunday bringing light snow to the Northeast and Monday bringing heavy rain, warm temperatures and thunderstorms. There is some uncertainty with the storm’s smaller details, though the overall picture is generally clear.

A storm is expected to develop in the Rockies on Sunday, moving towards the Ohio Valley on Monday. The exact timing is still uncertain, though from there, the storm is expected to move through the western Northeast overnight. The latest NAM run took the low pressure right over the area, though this is still the NAM’s longer range where its accuracy is not as good as its shorter range, and it is subject to changes. The storm will start in the overnight hours on Sunday, and with 850 mb temperatures above freezing and surface temperatures in the lower to mid 30s inland, the storm might start out with some light freezing rain in the interior parts of the area, though any freezing rain will not last long and will change over to rain by the time that the steadier precipitation moves in.

As the warm front moves through, a steady moderate to potentially heavy rain will affect the area from the early morning to the early or late afternoon hours. Temperatures will steadily rise throughout the day, and will peak sometime around the early overnight hours in the lower to mid 50s across most of the area with mid to upper 50s for the immediate NYC area. The exact time when temperatures will peak depends on the storm’s timing, ranging from the evening hours to the middle of the overnight hours. After the first round of rain ends, most models indicate a break in the rain, which may range from the mid afternoon hours to the early overnight hours. The cold front will then move through sometime during the overnight hours, bringing the potential for heavy rain and thunderstorms, which may produce gusty winds.

There is still uncertainty with parts of the storm, especially with the timing and the exact track, though the potential is there for heavy rain out of this storm with totals near or over 1 inch, which may lead to additional flooding in parts of the area, and there is also the potential for more rain, thunderstorms and gusty winds with the cold front in the overnight hours. Stay tuned for more information on this storm and how it may affect the area.

Longer Range: Behind this storm, temperatures will return to more seasonable levels with a stretch of dry conditions expected. These dry conditions will last until about March 5-7, when the next storm is expected. More information will be posted on the longer range as details become clearer.

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