June 17, 2011: Warmth Returns Next Week

As a low pressure moved through the region today, widespread showers and thunderstorms developed in the afternoon hours producing heavy rain and frequent cloud to ground lightning, and some of them produced hail in parts of the tri-state area, even in downtown Manhattan. As the low pressure exits the area with less instability, these showers have mostly dissipated, but some scattered showers continue to affect the eastern parts of the area.

Tomorrow will bring much warmer temperatures, reaching the upper 80s in parts of the immediate NYC area, but temperatures will slightly drop on Sunday and Monday with a risk of an isolated shower or thunderstorm each day. As a much warmer air mass moves into the region by mid week, however, temperatures will return well into the 80s in parts of the area, and may reach the lower 90s once again in parts of the immediate NYC area by Thursday.

Tomorrow’s Outlook:

With a WSW wind and partly sunny skies, temperatures tomorrow will rise into the 80s across most of the area. Mid to upper 80s are expected from NYC and further west, with upper 70s to lower 80s in Long Island and southern Connecticut. A few mid 80s may be possible closer to NYC.Today’s low pressure will be in the northern Northeast, bringing drier conditions to the area, but an isolated shower or thunderstorm cannot be ruled out tomorrow in the late afternoon and evening hours.

Sunday – Tuesday: Dry, Isolated Storms Possible

Originally, the NAM and GGEM models were showing a low pressure bringing heavy rain on Sunday with little support. In my Thursday update, I mentioned how such a solution was unlikely to verify, and that scattered showers and thunderstorms were more likely. Both models yesterday backed away from that solution, and now show partly sunny skies with the risk of an isolated shower or thunderstorm. Most places will stay dry, however, and the best risk of rain will stay to the south of NYC. Sunday will bring slightly cooler temperatures, reaching the lower to mid 80s from NYC and further west, and the mid 70s to lower 80s in Long Island and southern Connecticut.

For Monday, the NAM and GGEM once again try to repeat the same mistake they made for Sunday, by trying to bring another relatively strong low pressure through with moderate to heavy rain. The latest NAM run has backed away from this solution, but the 00z GGEM still showed this scenario. As with Sunday, I am expecting partly to mostly cloudy skies with scattered showers and thunderstorms, but the risk of storms on Monday is slightly higher than that of Sunday as this time, there will be a weak low pressure around. Temperatures will cool down slightly for Monday, reaching the upper 70s to lower 80s across the area.

On Tuesday, there is some uncertainty on whether the area will be north or south of the warm front. The GGEM and earlier NAM runs which showed the Monday storm keep the area north of the warm front on Tuesday and Wednesday. The GFS, meanwhile, keeps the area in the warm sector, with strong thunderstorms on Tuesday evening with temperatures rising well into the 80s. I am currently going with a solution close to the GFS but slightly cooler, with high temperatures reaching the mid to potentially upper 80s from NYC and further west on Tuesday, with a risk of an isolated thunderstorm in the evening.

Wednesday – Thursday: Warm, Stormy

By Wednesday, the area should be in the warm sector of the storm. Warmer temperatures will return, with high temperatures potentially reaching the lower 90s in parts of the immediate NYC area. Temperatures for Wednesday are still slightly uncertain, and could end up slightly warmer or colder. By Thursday, as the low pressure enters the region, temperatures may be warmer ahead of the cold front with 90s possible once again, and as the cold front approaches the area, there is a risk of strong to potentially severe thunderstorms in the afternoon and evening hours. Slightly cooler temperatures will return by next weekend. Stay tuned for more information on the warmth and potential storms for the area late next week.

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