Oct 2, 2011: Cold Continues Through This Week

As a cutoff low pressure remained stationary over the region, today brought partly to mostly cloudy skies across the area with isolated showers amounting to less than 1/4 inch. Due to the position of the cutoff low to the west of the area, the coldest temperatures across the region were observed in places such as Virginia and West Virginia, where daytime high temperatures stayed in the 40s and 50s. When combined with sub-freezing temperatures aloft, record early snowfall was observed in the higher elevations of West Virginia, Maryland, and Pennsylvania, with over 3-4 inches of snow reported in some areas. The NYC area saw below average temperatures but not as cold as those further southwest, reaching the lower to mid 60s inland, mid 60s in the immediate NYC area, and the mid to upper 60s in Long Island and southern Connecticut.

The colder temperatures aloft will drift towards the area tonight and tomorrow, which will result in temperatures slightly cooling down, peaking in the mid 50s to mid 60s across the area tomorrow along with low temperatures in the lower to upper 40s across the area. As the cutoff low drifts away and begins to phase with the main flow, a strong high pressure will move into the region, finally bringing an end to the cloudy and rainy conditions and starting an extended period of dry conditions and sunshine. Despite a brief warm up on Tuesday and Wednesday, another strong trough will move into the region, bringing below average temperatures once again to end the week, and the potential may be there for the first frost of the season for interior areas.

Tomorrow’s Outlook:

The cold air mass, currently centered over the Mid Atlantic, will slowly drift towards the area tomorrow, with 850 mb temperatures expected to end up near 1-3 degrees celsius, slightly cooler than the 850 mb temperatures today. As a result, slightly cooler temperatures are expected, peaking in the mid to upper 50s inland, upper 50s to lower 60s in the immediate NYC area, and the lower to mid 60s in Long Island and southern Connecticut. The easternmost parts of Long Island and SE Connecticut may see highs in the upper 60s. Mostly cloudy skies are expected with a SE wind, and isolated showers are expected once again.

Tuesday – Friday: Brief Warmth, Then Cold Again

The cutoff low will drift towards the coast of southern New England on Tuesday, which will keep mainly cloudy skies with scattered showers in the forecast. The cold air mass, however, will weaken, with temperatures aloft slightly warming up. Temperatures will begin to warm up on Tuesday, reaching the lower to mid 60s inland and the mid 60s across the rest of the area.

Tuesday should be the last day with widespread cloud cover and rain for a while, as the cutoff low finally departs from the Northeast. The upper level low will phase with a Canadian trough on Wednesday, which will take the low pressure further northeast, near Nova Scotia, where it will stall for a brief while. With a strong high pressure pushing south into the region from Canada and the low pressure positioned over Nova Scotia, mostly sunny skies and dry conditions are expected for Wednesday through the rest of the week. Warmer temperatures will briefly return into the area ahead of the trough, with high temperatures on Wednesday reaching the mid to upper 60s across the area. Parts of the immediate NYC area may reach 70 degrees.

There are still some differences with the models regarding the intensity and the location of the cold air mass, but the models are starting to converge on a solutions further west than yesterday’s runs, bringing colder temperatures into the area. For tonight’s forecast, I did not change the expectation from last night, expecting the cold temperatures to affect the area. Wednesday night will bring mostly clear skies with temperatures dropping into the lower to upper 40s across the area. With a NW wind on Thursday, chilly temperatures are expected, reaching the upper 50s to lower 60s across most of the area. Should the cold end up slightly east of the current expectation, temperatures would be slightly warmer than currently expected. With clear skies and light winds, Thursday night will be the coldest night, with low temperatures expected to drop into the 30s north and west of NYC. Should this scenario verify, the potential is there for the first frost of the season in the interior parts of the area. As the trough begins to exit the region on Friday, temperatures will slightly warm up, reaching the lower to mid 60s across most of the area. Stay tuned for more information on the cold spell.

Next Weekend – Next Week: Warmth Returns

With the high pressure settling over the Mid Atlantic, an extended period of dry conditions is expected, with no rain in sight through the weekend into early next week. Around this time, a pattern change is expected in the western US, which has been dominated by a strong ridge so far. A low pressure will bring a strong trough into the western US, which combined with the trough exiting the region and the high pressure in place, will push the existing warmth into the eastern half of the United States, resulting in widespread above average temperatures for next weekend into next week. Saturday will continue to slowly warm up, but at this time, the warmest temperatures are expected for Sunday and Monday. With 850 mb temperatures expected to be near 14-16 degrees celsius, temperatures will likely surge well into the 70s, and even lower 80s cannot be ruled out in the warmer case scenario. By the second half of next week, there is more uncertainty in the forecast due to the time range, but with the high pressure potentially exiting the region, the potential for stormy conditions may return. More information on the warm surge for next week will be posted as details becomes clearer.

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