Aug 30, 2011: Seasonable Pattern Develops

Note: The 5-Day Forecast page will be updated tomorrow morning.

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After Hurricane Irene affected the area with extreme rainfall and strong winds, a colder air mass moved in behind, bringing much nicer weather for the area over the last two days, with mostly sunny skies and slightly below average temperatures. A quiet weather pattern is expected to continue through the rest of this week with seasonable temperatures and dry conditions, and will last until this weekend, when an approaching cold front will bring a risk of thunderstorms.


Tomorrow's Outlook:

Tomorrow will be another nice day across the area. With a high pressure sticking over the region, mostly sunny skies are expected once again along with light winds. The air mass is expected to only slightly warm up, resulting in temperatures similar to, if not slightly warmer than those of today, peaking in the lower to mid 80s inland, mid 80s in the immediate NYC area, and in the lower 80s across most of Long Island/S CT except for the immediate coast, where temperatures should stay in the upper 70s.


Thursday - Friday: Seasonable Weather Continues

A heat wave is expected to build into the Ohio Valley and Great Lakes, with temperatures getting as high as the upper 90s in Illinois. Fortunately, the area will be spared from this surge of heat. A cut-off low pressure will begin to develop tomorrow in the western Atlantic Ocean, east of the Mid Atlantic, and with a high pressure sticking over the area, a SE wind is expected to develop, which will keep a cooler air mass over the region while the building heat wave will be blocked from reaching the Northeast. As a result, temperatures on Thursday will slightly cool down into the upper 70s to mid 80s from NYC and further west and the mid to upper 70s in Long Island/S CT, and Friday will bring colder temperatures, in the mid 70s to 80 degrees from NYC and further west, and in the mid 70s in Long Island/S CT.


Saturday And Beyond: Cold Front, Then Colder Air Mass

The low pressure driving the heat surge towards the Great Lakes will be in southern Canada on Friday, and is expected to move northeast through Canada. This will put the storm well north of the region on Saturday, and due to the storm being so far north, the cold front will be very weak when reaching the region, and will slowly move towards the area on Saturday, potentially stalling somewhere near the area.

With the cut off low pressure drifting away from the western Atlantic Ocean by Saturday, the leftovers of the heat surge will reach the area, with a warmer air mass and a southwest wind. As a result, warmer temperatures are expected, reaching the lower to mid 80s from NYC and further west and the upper 70s to lower 80s in Long Island/S CT. Due to the cold front, there is a risk of scattered thunderstorms in the late afternoon and evening, but at this time, any severe weather risk appears to stay low due to a lack of bulk shear and decent LI/CAPE values.

As previously mentioned, the cold front could stall somewhere near the northern Mid Atlantic or southern Northeast on Sunday. This would keep a risk of showers and/or thunderstorms in place across the area with temperatures in the mid 70s to lower 80s across the area. On Sunday night, another wave of low pressure could develop in the Great Lakes and move towards southern Canada on Monday, which would push the cold front through and bring a stronger chilly air mass into the region. Should this scenario verify, as the GFS model is currently showing, the timing is still uncertain, but should the potential storm slow down so that the front moves through in the evening hours, the potential is there that the area may see another round of thunderstorms on Monday. Stay tuned for more information on the potential Sunday-Monday storm.


Longer Range Outlook: Behind the cold front, a much colder air mass could move into the region, potentially bringing high temperatures in NYC as low as the lower to mid 70s for the middle of next week, which is below average. Such a cool down will be able to keep Tropical Storm, soon to be hurricane Katia, well east of the region, only affecting Bermuda and Newfoundland. This is the expected scenario at this time, but it is possible that the forecast could change, which could potentially bring Katia closer to the Unisted States. Stay tuned for more information on the longer range.