May 22, 2011: Pattern Becoming More Summer-Like

Note: The 5-Day Forecast page was not updated tonight. Tomorrow night, I will update the 5-Day Forecast page, as well as the Long Range Forecasts page for more information about the potential warmth for early June. This year’s Atlantic hurricane season and summer outlooks will be posted later this coming week as well.


As a cut off low pressure left the region yesterday, nicer conditions returned into the area, with yesterday’s high temperatures in the mid to upper 70s from NYC and further west, and in the mid 60s to mid 70s in Long Island and southern Connecticut. Scattered thunderstorms were observed, especially NW, north and NE of NYC, however these storms brought up to 1/4-1/2 inch at most.

As a high pressure moved down the coast from Canada, however, today brought much colder temperatures along with a southeast wind. Temperatures were colder than originally expected, only peaking in the upper 50s to lower 60s across the area. Cloudy skies and drizzle were observed throughout the day.

Today’s chilly conditions will only be brief, however. A storm to the west of the region tomorrow will bring a warmer air mass, and while tomorrow will slowly warm up, Tuesday will bring the first day over 80 degrees to NYC this month, unusually late for May, along with a strong thunderstorm risk. While Wednesday will be slightly cooler, Thursday will bring warmer temperatures along with another potential of thunderstorms, and even though a slightly colder air mass will move in during the Memorial Day weekend, the potential is there for sustained warmth beyond next weekend.

Tomorrow’s Outlook: Warmer, Some Storms

The high pressure east of the area today will move east, away from the region, but will still have enough of an influence to limit tomorrow’s high temperatures from getting much warmer. A significant warmer air mass will move in tomorrow ahead of a low pressure in the Great Lakes, with temperatures at 850 mb reaching the 12-15c range, but with a SSE wind expected, temperatures will not warm up as much, especially east of NYC. High temperatures are expected to be in the upper 60s to lower 70s from NYC and further west except for the immediate coast of NYC, and Long Island/southern Connecticut will see highs in the upper 50s to mid 60s.

Along with the warm air mass and storm comes a severe weather risk. With NYC on the edge of the supportive parameters, the severe weather risk in the area is low, and is mostly from NYC and further west, with the best risk of severe weather existing to the west of the area. Parameters across the region are supportive enough for some severe thunderstorms, though the risk is relatively low, at 15%, focusing on Pennsylvania and western NY as well as parts of Virginia. Some severe thunderstorms may reach the western parts of the area, towards NW NJ and Orange County, NY, but will weaken as they move east towards NYC.

Tuesday – Thursday: Warm, Additional Storms
With the cold front west of the area on Tuesday, warm temperatures will finally be able to reach the area, peaking in the lower to mid 80s from NYC and further west, and a few lower 80s are possible in SW CT and western Long Island as well. With moderately supportive parameters and a risk of precipitation, there is a slight risk of strong to severe thunderstorms, especially from NYC and further west, with the storms mostly focusing on the late afternoon and evening hours.
The cold front is expected to stall near the area on Wednesday, bringing slightly colder temperatures, reaching the mid to upper 70s from NYC and further west, and the upper 60s to mid 70s for Long Island and southern Connecticut. A few showers or thunderstorms are possible, but storms are unlikely to be widespread.
By Thursday, however, as a low pressure intensifies to the west of the region, it is expected to pull in a warmer air mass ahead of another cold front. How warm it gets depends on the location and speed of the storm, as it appears that onshore winds could limit temperatures in parts of the area, but there is the potential for temperatures to once again reach the lower to mid 80s from NYC and further west in the warmer case scenario. This cold front is capable of producing more severe weather in the region, with the best risk of severe weather once again west of the area, however it is possible that there may also be some strong/severe storms in the area. Stay tuned for more information on Thursday’s potential storms.

Friday and beyond:
There is some uncertainty on what happens on Friday and Memorial Weekend, but at this time, despite the risk of some showers, no washout is expected, with temperatures in the 70s and potentially lower 80s. If the storm moves slower than expected, the cold front would move through on Friday, not Thursday, bringing warm temperatures and a strong/severe thunderstorm risk as well. While this is not shown by most models at this time, it will be watched in case it becomes a trend.
There is uncertainty on the longer range as usual, but beyond the Memorial Weekend, the long range models are suggesting the possibility of a significant warm spell affecting the central and eastern United States, including the area. This is still too far in the long range to know for sure, and it is possible that there is no significant warm up, but the potential is there for the first major warm spell of the year in the NYC area. More information will be posted as details become clearer.

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