Oct 3, 2012: Warmth Persists Through Friday

Forecast Highlights:

– Warmth sticks around through Friday
– Clouds/showers return Thurs; brief clearing on Friday
– Weekend: much cooler, cloudy with some rain
– Chilly start to next week, then warmer

 

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After several days of technical difficulties, updates to the blog will continue starting tonight. The Long Range Forecasts page has been updated with the October outlook, and the 5-Day Forecast will be updated on Thursday.

Additionally, I am working on updating the brief daily weather summaries as the last update was in early September. Throughout the next 1-2 weeks, daily weather summaries will be added in each day’s respective post, or the following day(s) if there was no update on a specific day.

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Tonight – Friday: Mild, Some Rain

Little drop in temperatures is expected tonight with a humid air mass still in place. Scattered showers are expected on Thursday, locally heavy north/west of NYC; highs are generally expected to peak in the low to mid 70s inland, mid to possibly upper 70s in the immediate NYC area, and in the upper 60s to mid 70s in Long Island and southern CT.

A drier SW flow will briefly return on Friday with more sunshine expected, although this break from the cloudy and rainy pattern will only be brief. Highs are expected to be slightly warmer than those of Thursday, reaching the mid to upper 70s from NYC and further north/west, perhaps reaching the low 80s in parts of NE NJ, with low to mid 70s, locally upper 70s, in Long Island and southern CT.

Weekend Outlook: Cloudy, Colder, Some Rain

The last day under this mild air mass will be on Saturday as a cold front will slowly move through the region. A strong rex block is currently present off the coast of the western US and is expected to remain in place through the medium range, with a strong trough currently dropping into the north central US, producing a significant early season snowstorm in North Dakota and Minnesota. The large trough will gradually move into the region over the weekend, with the cooler temperatures moving east. Highs on Saturday are slightly uncertain and depend on the exact timing of the cold front; the GFS supports highs in the low 70s while the latest NAM run has nearly 80 degrees in NYC. At this time, I am siding with a solution slightly faster than the NAM, with highs in the low 70s inland, mid to upper 70s in the immediate NYC area, and the mid 70s across most of Long Island/S CT, slightly warmer/cooler in some spots. Showers will approach from Pennsylvania associated with the cold front, although most of these showers should dissipate before reaching the area. Regardless, at least a period of light to perhaps locally moderate showers is possible, if not likely around Saturday noon/evening, especially north/west of NYC.

The cold front will be slow to move east of the area, and on Sunday, a weak wave of low pressure will move along the front near or off the coast, producing clouds and a cold rain for parts of the region. There are some model differences with the location and intensity of the wave, as although most of the model guidance shows the wave affecting the area with a cold rain, the latest GFS run keeps the wave southeast of the area, continuing a southeast trend on the GFS. The high temperatures on Sunday depend on the timing and location of the storm; the models are split into two camps, with the GFS and the ECM bringing in the rain by the morning/afternoon with highs only in the upper 40s to mid 50s from NYC and further north/west and warmer further east. The CMC and NAM are slower with the storm, delaying the rain until later in the day, allowing temperatures to warm up well into the 50s and the low 60s for some before the rain arrives and temperatures drop into the 40s overnight. Given that the CMC has not had a good handle on this storm until now and considering the NAM’s occasional slow bias, I sided towards a solution slightly faster than these two models, with showers likely on Sunday with highs likely in the mid to upper 50s across most of the area, perhaps cooler in western areas. This will not be a significant rain producer, and generally around 1/2 inch of rain is possible, perhaps a bit more or less. There is still some uncertainty with the storm, however, and it is a possibility that the wave mostly misses the area, with warmer temperatures, or could end up stronger than currently expected. Stay tuned for more information on the weekend outlook.

Next Week: Chilly Start, Then Warmer

Behind the wave of low pressure, the cold air mass from the west will struggle to fully move into the region, although it will still produce below average temperatures. Monday will be the coldest day with highs likely in the mid 50s inland and the upper 50s across the rest of the area, perhaps reaching 60 degrees in the immediate NYC area. Widespread cold temperatures are expected on Monday night, with lows dropping into the mid 30s inland and the upper 30s to mid 40s across the rest of the area with upper 40s to low 50s in NYC.

As previously mentioned, the cold air mass will struggle to move into the region, and will lift out by the middle of next week as a SW flow briefly returns. Highs will warm back up into the 60s by Tuesday and Wednesday, with another cold front likely to move into the region by Wednesday with rain possible. By then, the pattern will become slightly less amplified as the strong block off the western US coast weakens. Another trough looks to move into the region with cooler temperatures towards the second half of next week; for the medium range, through perhaps the time frame around next weekend, a trough could remain over the region; uncertainty increases beyond this time frame due to the time range, although I would not be surprised to see a warmer pattern, although not nearly to the extent of last year’s warm pattern, beyond that time frame. Stay tuned for more information on the longer range.

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