Nov 12, 2011: No End To Mild Pattern In Sight

As the trough in place over the region yesterday moved out, today brought a breezy SW wind, with gusts peaking in the 20-30 mph range across most of the area. With the cold moving out, warmer temperatures returned, with high temperatures peaking in the mid 50s across most of the area and the mid to upper 50s in the immediate NYC area.

As we have already seen twice so far this month, another strong ridge will develop over the eastern US behind this trough, with temperatures once again getting to near 70 degrees early next week, near 15 degrees above the average for this time of the year. A cold front will move through the area between Tuesday night and Wednesday, bringing a stronger trough with near average temperatures by the second half of next week, although not surprisingly, this trough will quickly move out as well, which will be followed by above to well above average temperatures returning once again by next weekend, bringing no end to the warm pattern in sight.

Tomorrow’s Outlook:

With the ridge building into the region, a SSW wind is expected for tomorrow, although the winds won’t be as strong as today, with gusts locally up to 20-25 mph possible. The SSW winds, along with warmer temperatures aloft, will bring warmer temperatures into the area, reaching the upper 50s to lower 60s across most of the area. Temperatures will get close to 65 degrees in parts of the immediate NYC area.

Monday – Wednesday: Unseasonably Warm

With a trough in the western US, a strong ridge will remain in place on Monday, with the SSW wind persisting. 850 mb temperatures warming up to nearly 10 degrees celsius will result in even warmer temperatures, reaching the lower to mid 60s across the area with the warmest temperatures in the immediate NYC area. Partly to mostly cloudy skies are expected on Monday, and although an isolated shower may be possible, no widespread showers are expected on Monday and Monday night.

By Tuesday, a stronger cold front will move towards the region. With warmer temperatures spreading into the area from the southwest, widespread highs in the mid to upper 60s are expected across the area. Mostly cloudy skies are expected, but if there is more sunshine than currently expected, parts of NE NJ may reach the 70 degree mark, which is over 15 degrees above average for this time of the year. No rain is expected to fall during the day at this time, although a slight risk of showers is in place especially towards the afternoon and evening hours. As the front approaches the area, light to moderate rain is expected to fall on Tuesday night, and while still uncertain, some models extend the risk of rain through Wednesday. For now, I am keeping only a slight risk of rain in the forecast for Wednesday, although the forecast is still subject to change. If the models trend towards this scenario, I may change my forecast to slightly lower Tuesday’s temperatures while slightly warming Wednesday’s temperatures, reaching the lower to upper 60s, along with a higher rain risk. Stay tuned for more information on Tuesday and Wednesday’s storm.

Thursday And Longer Range: Cold Start; Significant Warmth Returns Again

Behind this cold front, a trough will move into the region, bringing colder temperatures for Thursday and Friday. The exact intensity of the cold air mass is uncertain, but colder 850 mb temperatures are expected, likely dropping below -5 degrees celsius. This will result in high temperatures dropping into the mid 40s to lower 50s across the area, with low temperatures likely in the mid 20s to mid 30s, with the coldest temperatures inland and the warmest temperatures in NYC. Friday’s temperatures will slightly warm up into the upper 40s to lower 50s across most of the area.

So far, we have a slightly negative NAO pattern, although the NAO is east based, which is not supportive of cold in the East US, but the pattern is dominated by a very strong negative PNA and a positive EPO, which is keeping a warm pattern locked over the eastern half of the US. As we have seen and will see through the rest of this month, there will be occasional cold spells in this pattern, but as long as the -PNA and the +EPO pattern persists, these troughs will remain transient, quickly moving out as more ridges build over the eastern US, resulting in a warmer than average pattern. With no change in the pattern, this upcoming weekend will bring another trough into the western US, and not surprisingly, another ridge will build into the eastern US, likely focusing on the Saturday to Tuesday time frame, 11/19 to 11/22. The intensity and the timing of the warmth is still uncertain considering the time range, but if the overall set up ends up close to the current thinking and what we have seen so far under this pattern, it is very possible that widespread highs in the mid to upper 60s return towards this time frame, potentially bringing yet another round of well above average temperatures.

There are a few signs showing improvement in the Pacific pattern towards slightly more cold in the East, including a moderating -PNA, trending towards neutral, although the EPO and AO remain positive with the NAO trending towards slightly positive as well. Considering the teleconnections and the pattern we are in, a turn to a colder pattern is unlikely before early December, and if we do turn to a more sustained cold/potentially snow pattern, it would likely wait until early to mid December at the earliest, if not slightly afterwards. Stay tuned for more information on the long range pattern.

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