Mar 10, 2012: Pattern Becomes May-Like

Forecast Highlights:

– Temperatures increase; 70-75 degrees by Tuesday
– Colder but still unseasonably warm late this week
– Pattern to resemble that of a typical May rather than March
– Even more warmth by weekend, next week; 75+ degrees possible


After an unseasonable surge of warmth on Tuesday, with temperatures getting as warm as the lower 70s in the immediate NYC area, temperatures have noticeably cooled down over the last two days, with today’s temperatures only reaching the lower to mid 40s across the area, slightly colder than expected.

A high pressure will remain near the region, keeping mostly sunny skies in place through Monday, although temperatures will begin to increase tomorrow again, reaching the mid 50s to lower 60s tomorrow and the lower to upper 60s on Monday. Unlike the previous warm spell, however, there is no incoming feature to completely remove the warmth, and as a result an unusually strong and prolonged warm spell for March will develop for almost the entire eastern half of the US, lasting through this week and next week as well.

Tomorrow’s Outlook:

With a high pressure in place along with a warmer air mass, SW winds, and mostly sunny skies, much warmer temperatures will begin to return tomorrow. High temperatures are expected to reach the upper 50s to lower 60s across northern NJ, SE NY and NYC, with mid to upper 50s in Long Island and southern CT except for the immediate coast, which is likely to stay in the lower 50s for highs.

Monday – Tuesday: Much Warmer, Some Rain

Temperatures will continue to warm up on Monday, with highs reaching the mid to upper 60s in northern NJ, SE NY and NYC, with upper 50s to mid 60s across most of Long Island and southern CT, along with SW winds. Mostly sunny skies are expected, although cloud cover should increase by the late afternoon and evening hours.

As the cutoff low pressure currently near the southern US drifts towards the region, mainly cloudy skies are expected on Monday night with areas of light rain expected to affect the area between 12-2 AM and the morning hours on Tuesday, perhaps accompanied by some fog. Cloud cover is then expected to partially clear by Tuesday afternoon, and with SW winds returning ahead of the approaching cold front, warm temperatures are likely again, reaching the upper 60s to lower 70s across northern NJ, SE NY and NYC, with highs in the lower to mid 60s across most of Long Island and southern CT, likely peaking in the upper 60s closer to NYC and in the upper 50s to lower 60s near the immediate coast. Should there be more sunshine, highs may get close to 75 degrees near NYC.

As mentioned with the previous update 2 days ago, there was some uncertainty with the models regarding the cutoff low, and I sided with the ECM, which suppressed the cutoff low and brought a cold front through the area. The rest of the models have trended towards this direction, also showing the cold front moving through around Tuesday evening/night. Some of the models, especially the NAM, are showing marginal instability for Tuesday just ahead of the cold front, and while the cold front will be mostly dry, an isolated shower or thunderstorm cannot be ruled out for the evening hours.

Wednesday – Longer Range: Unseasonable Warmth Continues

Behind the cold front on Tuesday, a colder air mass will move through New England, with the area on its southwestern side, while the rest of the eastern half of the US continues to see very warm temperatures. Temperatures for Tuesday night will drop into the lower to upper 40s across most of the area, with highs on Wednesday reaching the upper 50s to possibly lower 60s north and east of NYC, and the lower to possibly mid 60s from NYC and further west and south. Temperatures on Wednesday night are expected to be similar to those of Tuesday night, if not slightly colder.

The biggest change with the models recently has been for Thursday; the cold front originally modeled to move through is now expected to be much weaker and further north, having no influence on the region. Without the cold front, almost all signs of winter-like cold will be erased from the pattern over the US, except for the NW US which will continue to see cold and stormy conditions, and a very strong and prolonged warm spell for March will take place across the entire eastern half of the US, focusing over the central parts of the US. The warm air mass will slowly begin to move back towards the area on Thursday but will not be able to quickly spread back; instead, high temperatures are likely to remain similar to, if not slightly warmer, those of Wednesday, peaking in the lower to mid 60s in northern NJ, SE NY and NYC, and the mid to upper 50s in Long Island and southern CT, likely reaching the lower 50s near the immediate coast. Temperatures are still uncertain for Wednesday and Thursday; for now, I am leaning with the slightly cooler models, although temperatures could end up warmer than currently expected.

Between Friday and Sunday, a much warmer air mass will cover the entire region, but this time cloud cover and precipitation will limit the warmth; scattered showers, locally heavy, are likely to cover parts of the eastern US, although the location and coverage area of these showers is still uncertain. For these three days, temperatures assuming partly sunny skies have the potential to reach the upper 60s to mid 70s away from the coast; any day with showers and cloudy skies during the afternoon hours would be colder with highs staying in the 60s.

From the latest indications, it appears that the first potential time frame for the warm spell to end could be late next week. Around the first half of next week, depending on any cloud cover and precipitation, the potential is there for the warmest temperatures; with the warmest air mass moving through, if there is more sunshine, no precipitation, and no back door cold front to come through, the type of air mass over the region would be warm enough to support the potential for temperatures to even reach and/or exceed 80 degrees, which is very unusual for March. The temperatures are still uncertain and depend on the smaller parts of the set up, but the potential is there next week for at the very least one or two days to pass 75 degrees in parts of the area. Stay tuned for more information on the longer range warmth.

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