Sept 21, 2011: Wet Ending To September

As a front cleared the area last night, mostly cloudy skies were observed across the area today. A warmer air mass moved into the region, which brought warmer temperatures as well, peaking in the mid 70s across the entire area with a few upper 70s in the immediate NYC area. Scattered showers were observed as well, with less than 0.1 inch falling in places that did see rain today.

As an upper level low will begin to form over the Ohio Valley, moisture will move up the coast, with additional light rain expected tonight, amounting up to 1/4 inch in most areas, locally up to 1/2 inch. Moisture moving up from the tropics will bring more widespread moderate to heavy rain for Friday, however, with rainfall amounts exceeding the 2 inch mark in parts of the area by Friday night. With the upper level low sticking around over the region through the middle of next week, rain will remain in the forecast through mid-late next week, and by the time that the cut off low leaves the region sometime mid-late next week, as much as 3-5 inches of rain may be possible in parts of the area, bringing September’s rain totals well above the average.

Tomorrow’s Outlook:

Tomorrow will bring cloudy to mostly cloudy skies across the area. The showers expected for tonight will end up to the north of the area, though isolated showers are still possible throughout the day on Thursday, which could accumulate up to 1/4 inch. With a SSE/south wind expected, temperatures will be similar to those of today, peaking in the mid to upper 70s from NYC and further west and in the lower to mid 70s in Long Island and southern Connecticut.

Heavy Rain On Friday, Showers For Weekend

A surge of moisture is expected to move up the East Coast on Friday into Friday night as the cut off low develops over the Ohio Valley and tropical moisture begins to move up the coast. Steady rain will begin to develop across the area early on Friday morning, with the heavier rain expected to begin after noon and end around 12 AM. There is some slight uncertainty with the location of the heaviest rain, as the models up to this morning indicated that the heaviest rain would be east of NYC, but now show the heavier rain to also affect places west of NYC. For tonight’s forecast, I am expecting moderate to heavy rain across the area, with rain totals by Saturday morning between 1 and 3 inches across the area.

Drier conditions will return for Saturday and Sunday as the main round of rain moves out of the area. Mostly cloudy skies will continue for both days with scattered showers bringing up to at least 1/4 inch each day, and with the upper level low still to the west of the region, mild temperatures will continue, peaking in the mid to upper 70s from NYC and further west, and the lower to mid 70s east of NYC.

Next Week: Rain Continues

Another low pressure is expected to form around the upper level low early next week, which will bring more rain into the area. As the upper level low will begin to drift to the east, the rain will shift to the east as well, with the heaviest rain expected to fall from NYC and further north and east, and while there is uncertainty with amounts, at this time it appears that another 1/2 to 2 inches of rain may fall early next week. Stay tuned for more information on the rain totals for the potential rain event early next week.

It appears at this time that the upper level low should exit the region around Wednesday/Thursday, with drying conditions by Thursday and Friday. There is still uncertainty with the timing, however, which could be earlier or later than expected. Stay tuned for more information on next week’s outlook with tomorrow’s update.

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