June 30, 2011 Morning: Heat Returns Next Week

Note: Due to technical difficulties, no additional update was posted tonight. A brief update will be posted on Friday morning, with a more detailed discussion tomorrow evening.

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After a cold front moved through on Tuesday night, bringing scattered showers and thunderstorms mostly focusing over southern Connecticut, Wednesday was a partly to mostly cloudy and dry day across the area, with high temperatures reaching the upper 70s inland, lower to mid 80s in the immediate NYC area, and the upper 70s to lower 80s across Long Island and southern Connecticut.

Today and tomorrow will be dry and comfortable once again, with similar temperatures to those of yesterday. By the weekend, however, uncertainty increases as a large ridge begins to move towards the area, but may potentially be blocked by an upper level low off the coast. Regardless of what the upper level low does, however, some heat will manage to reach the area, with temperatures over the weekend and mid-late next week likely to reach the lower 90s in parts of the immediate NYC area along with occasional rain chances.

Today’s Outlook:

Today will be another seasonable day across the area. With a NW wind expected today, high temperatures will reach the upper 70s to lower 80s inland, lower to mid 80s in the immediate NYC area, and the upper 70s to lower 80s in Long Island and southern Connecticut. No rain is expected today.

Friday – Monday: Heat Starts To Build In

Friday will bring conditions similar to those of today as well, with similar temperatures, but this time with a NNW wind along with the risk of an isolated thunderstorm north of NYC. By Saturday, the massive ridge currently building in the central US will reach the region, but how it affects the area is still uncertain. As mentioned with last night’s update, the latest models have trended towards an upper level low (ULL) sticking off the coast, completely preventing the heat from reaching the area other than a one day heat surge, which would likely end up on Sunday with this scenario. The NAM and GFS runs continued to trend in this direction, with the GFS slowly trending towards a stronger ULL, but the main difference is that the GFS shows the upper level low far enough from the coast to prevent it from completely blocking the heat while moving the ULL away from the coast towards New England, allowing heat to move in on Sunday. The ECMWF and GGEM, however, show the ULL closer to the coast and stall it there for 2 days, preventing the heat from coming in.

As mentioned above, there are currently two possibilities for this weekend. One possibility is that the ULL moves away from the region by Saturday/Sunday, with the result being a shorter heat spell but with the heat still reaching the area, bringing highs in the upper 80s to NYC on Saturday and the lower 90s on Sunday, with these temperatures sticking through most of next week. The other possibility is that the ULL sticks off the coast, keeping temperatures in the lower to potentially upper 80s with partly to mostly cloudy skies and occasional rain chances. At this time, I am going with a scenario slightly closer to the GFS but with some differences, expecting warming temperatures on Saturday and Sunday, reaching the lower 90s in parts of the immediate NYC area on Sunday as a cold front reaches the area, resulting in cooler temperatures, back into the mid to upper 80s. There is still some uncertainty with this scenario, and the current forecast may slightly change over the next day or two.

Next Week: Some Heat Continues

The differences for this weekend continue through next week as well, with the warmer GFS keeping temperatures in the upper 80s to lower 90s stuck through almost all of next week, while the GGEM and ECMWF keep colder temperatures for a longer period of time, with yesterday’s 12z ECMWF bringing in a much colder air mass by early-mid next week. At this time, I expect a cold front to move through on Sunday, bringing slightly cooler temperatures for Monday and Tuesday, but this is not expected to be a significant cool down, with temperatures likely dropping into the lower to upper 80s across the area for both days. As with the weekend, this is still uncertain, and is subject to some changes.

Some of the model runs, including the GGEM and ECMWF which are not very warm this weekend, show the ridge eventually rebuilding itself and reaching the area by Wednesday and Thursday, bringing warmer temperatures ahead of another cold front. The outcome for mid-late next week has more uncertainty due to differences with what happens in the weekend and the early week, but the potential is there for lower 90s to return into NYC by Wednesday and/or Thursday, followed by cooler temperatures for next weekend. Stay tuned for more information on the scenario for this weekend and next week over the next few days.

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