July 7, 2011: More Storms Tomorrow

Note: The 5-Day Forecast will be posted tomorrow in the early morning. Storm updates may be posted tomorrow morning and afternoon, but otherwise, the next full update will be posted on Saturday night.

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The area saw its fourth consecutive day of heat as temperatures surged into the upper 80s to lower 90s inland, lower to mid 90s in most of the immediate NYC area, and mostly in the mid 80s to lower 90s across Long Island and southern Connecticut. Earlier this afternoon, isolated thunderstorms formed in the southern half of New York City and moved east through southern Long Island, but otherwise, most of the area stayed dry.

Since my discussion three days ago about the potential for the models to trend towards adding a feature to block the heat from easily spreading in, the models trended towards a low pressure moving towards Nova Scotia/Newfoundland and Greenland during the weekend, shortening the heat to a 2 day time frame, around Monday and Tuesday. As the low pressure will develop near the region tomorrow, however, this trend put the area under the risk of locally heavy rainfall tomorrow and tomorrow night, with occasional showers and thunderstorms bringing the potential for rain totals locally as high as 1 to 2 inches of rain.

Tomorrow’s Outlook:

As previously mentioned, a low pressure will begin to develop near the region tomorrow, which will later on become a stronger storm moving towards Nova Scotia and Newfoundland. This low pressure will not be very organized yet tomorrow, but it will produce scattered showers and thunderstorms, which will be capable of producing locally heavy rain with precipitable water values near 2 inches. It is possible that some places in the tri-state area may fail to see rain, but at this time, the coverage area of the rain is expected to be widespread enough to affect at least most of the area. Due to the cloud cover and rain, tomorrow will bring cooler temperatures, peaking in the mid 70s to lower 80s across the area. Storm updates may be posted tomorrow in the morning and afternoon hours.

Weekend To Early Next Week: Warming Up

A few days ago, on July 4th, the models were expecting a transition to a positive NAO with a large surge of heat spreading into the region. My update that afternoon mentioned that the models have done the same for this week and ended up trending towards a negative NAO and a low pressure near the Davis Strait, keeping any heat surge relatively weak and preventing it from becoming sustained. We are seeing the models repeating this trend, as the latest consensus is there for the low pressure which will form near the region tomorrow to move towards Newfoundland and then towards Greenland. While it is unlikely to move into the Davis Strait as the last few storms in that region have done, a negative NAO will persist, and is expected to remain mostly negative or neutral through mid July.

With the storm moving into the Newfoundland/Greenland region, the entrance of the heat into the region will be delayed, with lower 90s expected to make an appearance in parts of the area on Monday and potentially Tuesday. Mid to upper 80s are expected from NYC and further west on Sunday, with parts of NE NJ potentially reaching the 90 degree mark. With a high pressure nearby, mostly sunny skies are expected for Sunday and Monday.

By Tuesday, a storm moving from west to east through southern Canada will bring an end to the short lasting surge of heat. The cold front will move through around Tuesday, and while the exact timing is still uncertain, there is the potential for thunderstorms with this cold front, especially around Monday night and potentially on Tuesday if the cold front slows down from the current expectation.

Longer Range: Cool Down, Then Warming Up

Behind the front, the pattern we are currently under will repeat itself once again, as the models have trended away from the original idea of a longer lasting heat spell lasting through next week and now show a trough moving into the region. This will not bring a much colder air mass, but temperatures are expected to cool down into at least the upper 70s to mid 80s through mid-late next week with mainly sunny skies. There are indications that the area may warm up once again by next weekend, but the specific details cannot be nailed down yet as this is still in the longer range. Stay tuned for more information on the longer range.

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