May 18, 2012: Memorial Day Heat Potential

Forecast Highlights:

– Sunny, mild conditions last through Saturday
– Clouds, scattered showers to gradually return Sun Night to Wednesday
– Somewhat drier/mild ending to next week
– Heat surge possible around/after Memorial Day Weekend


Today’s Observations:

Today was the 2nd mainly sunny day in the row for the area, with mild temperatures observed close to average. High temperatures ended up slightly cooler than expected, reaching the mid to upper 60s in Long Island and southern CT, and the lower to mid 70s from NYC and further north/west.

Sunny skies and mild temperatures are expected again tomorrow, as well as Sunday for interior areas, although an approaching cutoff low will result in increased clouds and scattered showers for the first part of the upcoming week. There is uncertainty with another potential cutoff low afterwards, although the potential exists for a significant warm spell around or after Memorial Day Weekend.

Weekend Outlook:

Mainly sunny skies are expected to continue tomorrow, with NE/ENE winds expected again. High temperatures will reach the upper 70s to lower 80s from NYC and further north/west, with lower to mid 70s expected in most of Long Island/southern CT. Places closer to NYC may see highs in the upper 70s, with eastern areas failing to pass 70 degrees.

By Sunday, a cutoff low pressure to the south will begin to move north, with a sunny start to the day expected but with increasing clouds. I am currently siding with the slower timing for the low, with showers reaching the region by Monday with clouds developing later in the day/evening on Sunday. As a result, temperatures inland are likely to reach the lower 80s again, with similar temperatures to those of Saturday near NYC and slightly cooler temperatures possible in Long Island/S CT.

Next Week: More Clouds, Some Rain

The cutoff low pressure to the south will move into the region on Monday and Tuesday, producing mostly cloudy skies and scattered showers, although the main low pressure is expected to stay to the east of the area. No heavy rain totals are expected, except for perhaps isolated heavy amounts in the eastern parts of the area. Otherwise, most places are expected to see up to 1/2 inch of rain. Temperatures on Monday are expected to reach the upper 60s to lower 70s from NYC and north/west and the lower to upper 60s in Long Island/S CT, with temperatures on Tuesday slightly warming up into the mid 60s to lower 70s in Long Island/S CT and the lower to mid 70s for the rest of the area.

Behind the cutoff low pressure, a trough will approach from the west, with another upper level low likely to get stuck over the region as a result. Wednesday, Thursday and Friday aren’t expected to be as cloudy, cool and rainy as the first half of the week, although partly to mostly cloudy skies and a risk of scattered showers is likely to persist through Thursday and/or Friday. Currently, the GFS model quickly pushes out the upper level low, although given how it also quickly pushed out the cutoff low for this weekend, a somewhat slower solution is likely to take place.

Memorial Day Weekend: Strong Warmth Potential

With the ULL (upper level low) near the region and a trough dropping into the western US, a large ridge is expected to build into the central US starting late next week. Given the recent pattern, the core of the heat will stay in the central US, where there is a high probability of temperatures reaching the 90s for highs. The models are still struggling to handle the specifics of this time period due to differences with the ULL and the pattern in Canada, with some dropping a back door cold front through the region, others such as the 12z ECMWF bring a short lasting heat surge into the region, and finally there’s the 12z GFS/18z DGEX, which developed a very strong ridge with temperatures exceeding 95 degrees for 2+ days. The GFS/DGEX solution is exaggerated, although given the pattern in place, there is a reasonable possibility that at least a brief surge of heat moves through the region around or after Memorial Day Weekend, when temperatures have the potential to reach 90 degrees for parts of the region. Stay tuned for more information on the Memorial Day Weekend outlook.

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