Oct 5, 2011: Frost Tonight, Tomorrow Night

As the cutoff low finally exited the region last night, sunny to mostly sunny skies were observed across the area today; this was only the second time this has happened since unsettled conditions moved into the area on September 20. A brief warm surge moved into the area today, bringing temperatures into the upper 60s to lower 70s inland, lower to mid 70s in the immediate NYC area, and the lower 70s across most of Long Island and southern Connecticut.

A strong high pressure will enter the region tomorrow and will settle over the Mid Atlantic, bringing a prolonged period of dry and sunny conditions, lasting through early next week. Temperatures will start out chilly, with low temperatures dropping into the 30s for interior parts of the area tonight and tomorrow night leading to areas of frost. By the weekend, however, temperatures will significantly warm up, with high temperatures passing the 80 degree mark across parts of, if not most of the area. By the second half of next week, however, attention turns to the Gulf of Mexico, where a potential tropical disturbance may bring a wet ending to the week across the East Coast.

Tomorrow’s Outlook:

A cold air mass will move into the Northeast tomorrow along with a high pressure, providing colder than average temperatures along with a widespread frost in the Northeast. The low pressure pulling in this cold air mass will be located over Newfoundland, which is well to the northeast of the region, thus keeping the NYC area near the western end of the cold. High temperatures will be near to slightly below average, but low temperatures will be below average due to radiational cooling.

Sunny skies are expected across the area tomorrow with a light NW wind. High temperatures will be colder than those of today, reaching the mid 60s from NYC and further west, and the lower to mid 60s for Long Island and southern Connecticut. A few upper 60s may be possible near and southwest of NYC.

Tomorrow night will bring cold temperatures once again. As with tonight, low temperatures will drop into the mid to upper 30s in NW NJ/SE NY, upper 30s southern CT, upper 30s to lower 40s in Long Island, lower to mid 40s in the immediate north/west suburbs of NYC, and the upper 40s in NYC. With clear skies, light winds, and temperatures getting very close to the freezing point, areas of frost are likely in the interior parts of the area.

Friday – Tuesday: Significant Warm Up Expected

By Friday, temperatures will begin to slightly warm up as the cold air mass exits the region. High temperatures will reach the mid to upper 60s from NYC and further west, and the mid 60s in Long Island and southern Connecticut. With the high pressure remaining stationary over the region, sunny skies and light winds will continue. During the weekend, however, a much warmer air mass will move into the region. A large ridge currently bringing widespread above average temperatures in the central US will shift further east, covering the entire East Coast by Saturday. Combined with the high pressure providing sunny skies and west/WNW winds, well above average temperatures are expected for next weekend. Temperatures on Saturday will climb into the lower to mid 70s across the area.

Sunday will be the warmest day, with 850 mb temperatures climbing to nearly 16 degrees celsius, which under the right conditions can easily bring temperatures above the 80 degree mark. High temperatures on Sunday will reach the lower 80s from NYC and further west, with upper 70s expected across most of Long Island and southern Connecticut. Temperatures in parts of the immediate NYC area may even reach the mid 80s. While it is not uncommon to pass the 80 degree mark in October, it does not happen every year. Most of the area never reached 80 degrees during the entire month of October 2010. The last time New York City reached 80 degrees in October was in 2007, when an unusual October heat wave brought temperatures into the lower 90s in parts of the area.

The warmth will begin to weaken by early next week, but the above to well above average temperatures will continue. The high pressure will slightly weaken early next week with a weak trough moving into the northern Northeast. This trough will not bring significantly colder temperatures below the northern Northeast, however, and temperatures across the area will stay in the mid to upper 70s through Tuesday, with a few lower 80s possible on Monday.

Late Next Week: Tropical Involvement?


Through Tuesday of next week, there is a high confidence level in the forecast due to the high pressure sticking around. Afterwards, however, uncertainty increases as attention turns to the tropics. The latest model guidance is in an agreement with showing a tropical or subtropical cyclone forming either near the eastern Gulf of Mexico or near the eastern Coast of Florida around early next week. This tropical disturbance would then move inland into the US, and may track through the Ohio Valley or the western half of the Northeast. As this disturbance is pulled inland, it will also bring a humid and moist air mass into the region, which may be capable of producing widespread rain, potentially heavy, across parts of the region for the second half of next week. The disturbance would then interact with a storm near the northern US, and even though there is increasing uncertainty by that time frame due to uncertainty with the location of the tropical disturbance, the potential interaction may bring colder temperatures into the region by next weekend. Stay tuned for more information on the potential rain event for late next week.

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