Dec 3, 2012: Little Cold, Snow Through Mid Month

Forecast Highlights:

As soon as meteorological winter began two days ago, the winter-like pattern in November fell apart, with a short lasting surge of warmth providing the region with widespread 50 and 60 degree weather through Tuesday for most and Wednesday for some areas further east. While cooler temperatures will return behind a cold front on Tuesday night, they will not be long lasting, with a warmer than average pattern with little snow chances continuing through at least the middle of the month as more clouds and rain return for parts of the weekend and especially early next week.


Monday, December 4 Observations:

A cold front moved through parts of the region last night after producing some rain, but failed to bring colder temperatures; instead, temperatures were even warmer for the area as a ridge persisted over the region as the front stalled just north of the area. No record high temperatures were broken, although temperatures were significantly warmer than average by as much as 10-15 degrees, peaking in the upper 50s to mid 60s across most of the area. More detailed temperature observations from today will be added on Tuesday.

Tonight – Wednesday: Warmth Continues

The aforementioned cold front stalled just north of the area today, and is now lifting through New England as a warm front, allowing for even warmer temperatures tomorrow that will once again be significantly warmer than average. With a south wind and gradually clearing skies, highs will peak in the low to mid 60s from NYC and further west, exceeding 65 degrees in parts of the immediate NYC area, and in the mid 50s to low 60s across Long Island and southern CT.

A stronger cold front will move through on Tuesday night, removing the warmth from the region as a transient trough quickly moves in and out of the region. After light rain on Tuesday night, especially later in the overnight hours, clearing skies are expected for Wednesday with a breezy NW wind as temperatures slightly rise into the low to mid 50s inland and the mid to upper 50s across the rest of the area.

Wednesday Night – Friday: Short Lasting Cold

With the current pattern in place, troughs moving into the region remain generally progressive, lacking strong cold and failing to hold in place, and the upcoming trough for the late week will be no exception to this trend. The coldest temperatures are expected on Wednesday night, with lows dropping into the low to mid 20s inland (NW NJ, interior SE NY) and into the mid to upper 20s for the rest of the area except for NYC and the immediate coast, which will be slightly warmer likely in the low 30s. Cold temperatures are then expected for Thursday, reaching the upper 30s to low 40s across most of the area, perhaps slightly warmer in the immediate NYC area.

Slightly warmer temperatures are expected for Thursday night compared to those of Wednesday night. Temperatures will already warm up again on Friday, reaching the mid 40s inland and the mid to upper 40s for the rest of the area, reaching 50 degrees in parts of the immediate NYC area.

Next Weekend – Next Week: Warmer, Rainy At Times

Cloudier and warmer conditions will return into the region by the weekend as a low pressure tracks to the north of the area on Saturday and Sunday, resulting in high temperatures returning into the low to mid 50s across the area, perhaps slightly warmer in the immediate NYC area, although partly to mostly cloudy skies and isolated showers will prevent temperatures from getting too warm. Occasional showers with mostly to mainly cloudy skies will continue through the early week as well with temperatures still above average, generally in the low 50s. The model guidance continues to have difficulties handling the early to mid week time frame, with stormy weather expected but the timing, intensity and location of the low pressure or multiple low pressures still uncertain. The overall idea at this time is for several weak waves of low pressure to track north of the region, keeping cloud cover and occasional showers in the forecast for Monday and possibly Tuesday, with a stronger storm likely tracking north and west of the area around Tuesday and/or Wednesday.

The continued difficulties for the model guidance in this time frame mean that the models will continue to change around with the set up over the next few days, and it is not out of the question to see a track much closer to the area or over NYC compared to what the latest models are showing, with the latest models showing a low pressure well to the west of the area, near the Great Lakes. With that said, however, the set up for this time frame including ridging in the east and ridging placed too far west of the west coast is not supportive of this tracking far south enough to be a widespread snowstorm for the area, and at this time the forecast is for plain rain in this time frame. Stay tuned for more information on the stormy weather for early next week.

Longer Range: Warmer Than Average December Still Expected

Over the last 1-2 weeks, the model guidance has been showing hints of a pattern change towards the medium to long range that would bring a much colder and snowier pattern to the US, and some models continue to indicate this going forward into the second half of December. While there are changes currently unfolding in the pattern, they are not favorable for a cold and snowy pattern for the eastern US going through 12/15, perhaps covering much of December. The persistent trough in the Gulf of Alaska is expected to break down by next weekend, with more ridging expected in the northeastern Pacific. However, the transient ridging is not located in a favorable position for a colder central-eastern US pattern, with the PNA remaining negative while the EPO remains positive, both of which can support warmer than average temperatures in the region. Blocking remains absent from Greenland, with only transient ridging expected at times near eastern Greenland with blocking still favoring Europe and Asia for a colder pattern. While this pattern is not expected to be as mild and snowless as last year, it is not a favorable one for persistent cold and snow either, and while a few snow events cannot be ruled out in this pattern, at this time there does not appear to be any significantly colder and snowier pattern on the way for the region, and the pattern may end up even warmer and less snowy than expected in the winter outlook through at least the last third of December, likely beyond but not certain at this time.

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