Nov 6, 2010: Cold, Rain For Monday

Today was a mostly cloudy day across the area, with high temperatures in the mid to upper 40s inland and in the lower to mid 50s for the rest of the area. Dry conditions were observed today. The trough is now pushing more into the area, which should lead to cold temperatures tonight, in the mid 20s inland, in the upper 20s to lower 30s for the north/west suburbs of NYC and southern CT, and in the mid 30s for NYC.

The forecast for the longer range, however, has gone through a significant change, which the part of the forecast up to Friday is discussed below. The forecast for the longer range beyond Friday will be discussed in more details in the next few days.

Tomorrow’s Outlook:

Tomorrow will be a mostly sunny day across the area, with a NNW wind expected. High temperatures will be in the mid to occasionally upper 40s inland, upper 40s to lower 50s north and west of NYC and in Long Island/S CT, and in the lower to mid 50s for NYC. Dry conditions are expected for the area.

Looking across the region, high temperatures will also be chilly throughout the Northeast but not as cold as today, with high temperatures in the 30s to lower 40s for New York and New England, though cloudy skies will develop across eastern New England, where light rain will start to fall tomorrow evening in SE Maine.

Monday – Tuesday Storm: Rain, Cold Now Expected

Yesterday’s update mentioned how at that time, some models started trending further southwest with the storm, and while partly cloudy skies were kept in the forecast, it was possible that the next update would show more cloud cover and/or a chance of rain. This is now the case, as the models have trended more southwest with the storm, now bringing rain for the area. This change will have a significant impact on the longer range, but that will be discussed in the section below this one.

According to the currently expected scenario, a cold air mass will be in place on Monday morning as the storm is negatively tilted and is near Boston, moving WSW. The storm will push moderate to heavy precipitation into eastern New England, spreading west. 850 mb temperatures will be below zero west and south of the storm track, with surface temperatures in the lower to mid 30s for most of these areas. This set up suggests that some snow and/or sleet could fall across much of southern New England on Monday morning, potentially including Boston, but focus on places away from the immediate coast, changing to rain later in the morning. Snow will also fall across the higher elevations of the Northeast, though most of Maine will not see snow under this set up, as the storm moving west will pull in a warmer air mass into Maine, leading to heavy rain in those areas.

As the storm moves into the area on Monday, it is expected to weaken, and it will also be the middle of the day with the cold 850 mb temperatures also weakening. High temperatures will likely be cold, and if the scenario above verifies, high temperatures could be in the upper 30s inland and lower to mid 40s in the immediate NYC area, meaning that the result would likely be a cold rain. If the storm can arrive fast enough, some frozen precipitation could fall in the immediate suburbs of NYC, but that is only a possibility at this time.

When the storm ends on Monday night, rainfall amounts in the area could range from 1/4 to 1/2 inch, with some snow/sleet possible in places such as southern Connecticut. In addition, windy conditions are possible for Monday and Monday night, with occasionally strong gusts possible. The models, however, are still trending a little, and it is possible that the forecast above could change a little by tomorrow’s update, with one possibility being that the storm shifts even more south, or that it trends a little warmer. Stay tuned for more details on this storm.

Mid-Late Week: Not As Warm?

At first, the set up strongly suggested that the late week would become much warmer, with highs into the mid 60s as far north as NYC. The storm was expected to keep moving east in the Atlantic, with Tomas’ remnants well to the south also moving east, with a high pressure from Canada spreading into the western Atlantic, leading to a warmer air mass spreading into the region. This small change in the storm, however, also led to a significant change in this time frame, which could lead to much colder temperatures than thought at first.

The low pressure is expected to move east into the western Atlantic on Tuesday, but the models are now all suggesting that Tomas should be absorbed by this low pressure. The result will be a large cut off low pressure stalled in the western Atlantic through most of the week, keeping colder 850 mb temperatures over the area with a NNE/NE wind, meaning that temperatures would stay in the lower to mid 50s for most of the area during the week.

This, like the storm, is only a recent change introduced by the models, and even though it’s near the short range, some trending on the models is still expected, and it is possible that the models stay with this solution or return to the previous one. Stay tuned for more details on this time frame.

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