Oct 22, 2010: Warmth To Return, Storm On Wednesday

Note: Two alerts are currently in effect for the area, a Frost Alert for most of the area other than NYC, and a Freeze Warning inland. In addition, I am currently working on my preliminary Winter 2010-2011 outlook, which will probably be posted sometime next week.

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Today was the coldest day of the year so far for many places, with high temperatures ranging from the upper 40s in the interior areas to the lower-mid 50s in the immediate NYC area. Due to more cloud cover than expected, the low temperatures this morning were slightly warmer than expected. This was associated with widespread showers in the Northeast, which combined with cold temperatures led to many places seeing their first snow showers in the Northeast this morning.

With clear skies, tonight will see very cold lows, as low as the upper 20s in Sussex/Orange counties, being why a freeze warning is in place for those areas, with frost alerts for the rest of the area except for NYC. Starting tomorrow, however, temperatures will steadily warm up, and a much warmer air mass will replace the current trough, leading to well above normal temperatures for early to mid next week, which will end with thunderstorms on Wednesday.

Tomorrow’s Outlook:

Tomorrow will be warmer than today but still chilly as the cold air mass lifts out of the region. High temperatures are expected to range from the upper 50s inland to the mid 60s in the immediate NYC area. A west wind is expected.

Sunday – Monday: Warming Up, Mainly Cloudy

A warm front will move through on Saturday night, bringing in a much warmer air mass, with 850 mb temperatures rising above 10c, which hasn’t happened in a while. Showers will fall in the central and northern Northeast, associated with a low pressure near the Midwest. While the northern Northeast will stay cold, the Mid Atlantic will significantly warm up, with high temperatures in the area ranging from the upper 60s to lower 70s, and upper 70s for southern Virginia.

On Sunday night, the warm front as well as the storm will continue to push northeast, bringing in even warmer 850 mb temperatures, while completely eliminating cold air from the United States, leaving a widespread mild pattern. What we need to pay attention to then is a strong storm entering the NW US on Sunday, which will influence the pattern for the rest of the week.

Monday will be a warmer day with mostly cloudy skies, with high temperatures from the upper 60s to mid 70s across the area, but it will only continue to get warmer from this point.

Tuesday – Wednesday: Strong Cold Front To End Warmth

Storm Set Up: As I previously mentioned, we need to pay attention to the storm entering the NW US on Sunday, which will drive the pattern for most of the week. Not much details have changed since I first discussed the set up of this storm several days ago, other than some minor timing differences. A low pressure related to the storm will form in SW Canada and move ESE, being just north of Montana on Monday afternoon. On Monday night, a low pressure will start to rapidly develop near Iowa, moving NNE, then merging with the storm further north to form an intense sub-970 mb low in Minnesota on Tuesday.

This storm, meanwhile, will start to pull down colder air into the north central US, while drawing in an even warmer air mass into the East, including the Mid Atlantic. As it reaches its peak intensity, the storm will be nearly stationary on Tuesday night, then start to move ENE while weakening. On Tuesday, the heaviest precipitation will be located near the Great Lakes, but on Tuesday night, will start to move eastward in the form of a line of potentially strong thunderstorms along a strong cold front, which will later affect the NYC area on Wednesday afternoon.

Storm Forecast: Some light to moderate rain is expected for the area on Monday night, but that will be from a different system. Tuesday will bring even warmer temperatures for the area, with highs in the lower to mid 70s, with Tuesday night being unusually mild for this time of the year, with lows in the upper 50s inland and lower to mid 60s for the immediate NYC area.

On Wednesday, the strong cold front will move through the area, bringing a round of rain and thunderstorms, potentially strong, and with precipitable water values nearing 2 inches, locally heavy rain is also possible with these storms. Wednesday is when the high temperatures will be at their warmest, potentially near the upper 70s in NYC, with mid 80s for southern Virginia.

Note that there are still several days left until this event, and there is still some uncertainty on the forecast, so it may change a little over the next few days. Stay tuned for more details on this storm.

Longer Range: Modified Cold Spell?

At this time, the models are suggesting that the pattern will be too progressive to allow for a low pressure to move inland through the eastern US as yesterday’s models suggested, with the trough simply moving into the region on Friday with a coastal low on Thursday night mainly staying offshore but potentially affecting the area. By then, however, the cold air mass will have moderated, and will bring temperatures similar to those of today, if not a little warmer. This is still in the longer range though, and there is uncertainty on this time frame, so it may still change over the next few days.

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