Sept 5: Pattern Of Extremes Begins


– The September Outlook has been posted in the Long Range Forecasts page, expecting slightly warmer and drier than normal conditions overall, despite more temperature extremes. A temperature map, as well as the temperature pattern outlook for the next 2 weeks, have also been posted there.

– I added a new poll, asking about your opinion on the quality of my Hurricane Earl coverage. Votes are appreciated, and will let me know if there is anything I can improve in future storm coverages.

– The 5-Day Forecast page has been updated for the area.


As a cold front that kept Hurricane Earl away from the NYC area brought a much cooler air mass into the area, temperatures were very comfortable over the last few days, with high temperatures in the lower to upper 70s across the area. This cooler air mass will continue through tomorrow, with the coldest temperatures since spring expected for tonight, but a pattern of extremes is now starting, where temperatures will switch every few days from above to below average.

Tonight’s Outlook:

Tonight will be very chilly for the area, with the coldest temperatures since the spring possible. Clear skies will support radiational cooling, which will put the interior areas in the lower to mid 40s, the north and west suburbs of NYC in the upper 40s to lower 50s, NYC in the mid 50s, southern CT in the upper 40s to lower 50s, and Long Island in the lower to mid 50s, with the cool spots near Riverhead also reaching the upper 40s.

Tomorrow’s Outlook:

Tomorrow (Monday) will be another nice day for the area, with sunny skies and high temperatures in the upper 70s inland, and upper 70s to lower 80s for the immediate NYC area. With a SW wind expected, Long Island and S CT will reach the upper 70s.

Tuesday And Wednesday: Next Warm Up

By Tuesday, a large warm air mass will spread into the area, with high temperatures much warmer than those of tomorrow, in the mid to upper 80s for the interior and the immediate NYC area, and with a SW wind, Long Island and S CT will reach the lower to mid 80s. Meanwhile, a storm will organize itself over southern Canada, with its cold front approaching the area, but most of its precipitation will stay to the north of the area, in New England, something that can be expected to be seen frequently this month. Wednesday will bring scattered showers as the cold front approaches, but the timing is still uncertain. At this time, I am leaning towards the slower NAM, with highs in the upper 80s to potentially lower 90s for the immediate NYC area and mid 80s inland, but this can still change.

Thursday – Saturday: Cool Down

Thursday and Friday will bring cooler temperatures to the area as the next trough moves in behind the cold front. With 850 mb temperatures between 6c and 10c, high temperatures will be in the mid (potentially lower) 70s inland, and in the mid to locally upper 70s for the rest of the area. By Saturday, however, temperatures will warm up ahead of the next warm spell. Some showers are possible on Saturday with the warm front, however most of the rain, as usual, will stay to our north.

Sunday: Next Warm Up Starts

By Sunday, there is more uncertainty in the forecast, however the next storm will likely be in New England, with a weak cold front potentially approaching. If the solution above verifies, the weak cold front may not be enough to bring in a cooler air mass, as another storm forms to the southwest, which would keep the warm temperatures through Tuesday. Despite uncertainty with the small details, it is likely that this warm up could last a few days, with temperatures returning well into the 80s again. Stay tuned for more details on this time frame and the longer range.

Brief Tropics Overview

With TS Earl already extra-tropical, there are two potential areas of tropical cyclone formation. The first one is in the western Gulf of Mexico, and is quickly organizing itself. This invest is likely to become a tropical depression by tomorrow, however it has a limited time before moving onshore, and I am currently giving this invest a 50% chance of becoming Tropical Storm Hermine. The remnants of this system could merge with Sunday’s storm, producing potentially heavy rain for the Northeast.

The second storm is related to the remnants of Tropical Storm Gaston, however ex-Gaston is currently in an unfavorable environment, with dry air, strong shear, and a rather disorganized appearance. For the short term, Gaston is not expected to regenerate, however for the longer range it could regenerate into a tropical storm.

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