Nov 27, 2011: Warmth Continues Through Tuesday

Note: The 5-Day Forecast will be updated later tonight for the area. In addition, the final winter outlook will likely be posted within the next few days.

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After a more zonal flow developed in the US late last week, a strong ridge built into the eastern half of the US, providing the NYC area with well above average temperatures. On Friday, 11/25, mostly sunny skies were observed with highs reaching the lower to mid 60s from NYC and further west and the upper 50s to lower 60s in Long Island/S CT. The peak high of 64 degrees was observed in Teterboro and Sussex in NJ. Saturday, 11/26, brought the warmest temperatures, surging into the lower to mid 60s inland, in Long Island, and southern Connecticut, with mid to upper 60s in the immediate NYC area. Temperatures as high as 67 and 68 degrees were observed in Teterboro and Newark, respectively. These temperatures matched records in parts of the area, such as Newark. With average high temperatures near 50 degrees, these temperatures were nearly 15-20 degrees above average in parts of the area.

With the ridge still stuck over the region, well above average temperatures will continue through Tuesday, when highs will likely reach the mid to upper 60s again in the immediate NYC area. A cutoff low forming in the southeastern US drifting north will bring a line of moderate to locally heavy rain for the area on Tuesday night. Although no sustained cold will form over the region, this storm will end the consistent warm spells over 60+ degrees as a somewhat colder start to December begins, with near to slightly below average temperatures expected.


Today and Monday:

Temperatures are currently peaking in the upper 50s to lower 60s inland, lower 60s in the immediate NYC area, and the upper 50s in Long Island and southern Connecticut. As a slow moving cold front approaches the area, mostly cloudy skies will continue through the overnight hours as well as some fog, with lows steady in the upper 40s to lower 50s inland and the lower to mid 50s across the rest of the area. To put the positive temperature departures into perspective, tonight's low temperatures will be approximately near the average high temperatures.

With the slow moving cold front approaching the area, tomorrow will bring mostly cloudy skies with fog possible in the morning. Temperatures will remain well above average again, peaking in the lower to mid 60s from NYC and further west and the lower 60s across most of Long Island and southern CT. Although the front will be over the region, it will fail to produce any significant rain until Tuesday night, as I will discuss in more details below.


Monday Night - Wednesday Morning: Storm Ends Record Breaking Warmth

Looking at the current set up over the US, there is a narrow but long trough in the central US, associated with a cold front currently affecting the Ohio Valley and the Southeast, with a strong ridge in the western and eastern US. The southern part of the trough will separate from the main flow and turn into a cutoff low over the southeastern US tomorrow, which will lead to some interesting results over the next few days. With the cutoff low pressure trapping cold air over the southeastern US, places such as northern Mississippi and Memphis, TN will see snow mixing with the rain tomorrow night, while New York City sees dry conditions with temperatures still well into the 60s. Although the cold front will be near the area on Monday, with the southern cutoff low intensifying, the front will retreat to the west on Monday night, with the warmth still persisting through Tuesday.

By Tuesday, the cutoff low will begin to drift north towards the Ohio Valley, bringing a cold front towards the region. With the area still in the warmer part of the system, temperaturess will once again reach the upper 50s to lower 60s across the area, but this time with an east/ESE wind. A line of moderate to locally heavy rain will move through the Mid Atlantic on Tuesday, reaching the area by at least 8-10 PM Tuesday night. As the low pressure merges back into the main flow, colder air from Canada will enter the storm, bringing more snow into places such as Michigan while the colder air mass associated with the cutoff low will move into the area from the south, ending the rain by at least 2 AM Wednesday, with 1/2 to 3/4 inch of rain expected across most of the area but with locally lower amounts still expected, ending up between 1/4 and 1/2 inch in some places. Stay tuned for more information on this storm and its impact on the region.


Wednesday - Friday: Colder, But Still Warmer Than Average
Behind Tuesday night's cold front, Wednesday will bring dry conditions with mostly cloudy skies. Temperatures will cool down significantly but will remain slightly above average, peaking in the upper 40s to lower 50s inland and the lower to mid 50s across the rest of the area. Overnight temperatures will be colder as well, dropping into the lower to mid 30s inland, mid to upper 30s in NE NJ, SE NY except for Orange county, and southern Connecticut, and upper 30s to lower 40s in Long Island and NYC.

With a high pressure moving in, mostly sunny skies are expected for Thursday, but with the cold air mass weakening, slightly above average temperatures will continue, peaking in the upper 40s inland and the lower 50s across the rest of the area. Although colder temperatures are expected for Thursday night, temperatures on Friday will be similar to those of Thursday with mostly to partly sunny skies expected.


Next Weekend And Beyond: Becoming Colder, But Not Very Cold

The pattern throughout November was a warm one, associated with 1-2 day troughs followed by a strong ridge setting up in the eastern US for several days, bringing high temperatures into the 60s. Today ended up as New York City's 11th day this month above 60 degrees; even though November 2009 and 2010 were warm as well, both of these months only had 6 days above 60 degrees in NYC. The warmth was able to settle into the East with the help of the Pacific pattern consisting of a -PNA and +EPO, driving warmth into the United States. The pattern is currently in the process of changing, but even though the change is towards less warmth, the pattern for the first half of December is not one that supports any strong cold and snowstorms.

The EPO is expected to become negative by early December along with a neutral to slightly positive PNA, supporting more ridging near the western US and Alaska. If combined with a -NAO and -AO, the -EPO/+PNA combination can be supportive of cold and snow in the eastern US. In this case, however, the Atlantic pattern is not as suppotive, with the AO remaining positive as well as the NAO, with no blocking west of Greenland to keep the cold locked in place. Although the overall pattern does appear to be a colder one, with weaker and less frequent warmth in between the cold spells, the lack of a -NAO/-AO will keep the cold relatively transient. The potential is there for slightly below average temperatures between December 5 and 15, with more frequent cold spells along with some warmth, and the possibility may be there for at least one snowstorm to affect parts of the region, perhaps including the area should the timing and location end up supportive, during this time frame. Stay tuned for more information about the long range with tomorrow's update, as well as the final winter outlook which will likely be posted within the next few days.