May 5, 2013: Rain, Possible Cool Temps To Return

Forecast Highlights:

After a week long stretch of mostly seasonable temperatures and a persistent high pressure in place, the blocking is gradually breaking down, which will allow for rain and clouds to return and persist for the second half of the week into next weekend, before a possible late season cool down early next week.

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This Week: Sunny Start, Wetter Ending

Expected Set-Up: Ridging has been sustained over the region for the last week, blocking a central US cold front from advancing east which later resulted in a cutoff low developing, currently located near Mississippi and slowly moving east/NE. Ridging over the region will gradually break down, allowing for the cutoff low to spread clouds and rain into the region by Tuesday into Wednesday, which are expected to persist through Thursday or Friday given the slow motion of the cutoff low until it reaches Canada and accelerates late in the week. Temperatures will initially be slightly cooler, but will fail to significantly cool down.

General Outlook: Mostly sunny skies are expected again for Monday, with highs peaking in the upper 50s to low 60s in Long Island and coastal CT, low to mid 60s in NYC, and mid to upper 60s north and west of NYC. Clouds will spread in by Tuesday with mostly cloudy skies and highs in the upper 50s to mid 60s in Long Island and coastal CT, mid to upper 60s in NYC, and upper 60s to low 70s north and west of NYC.

Occasional showers are expected on Wednesday with cloudy skies and highs in the mid 50s to low 60s across the area. Rain amounts appear to be mostly below 1/2 inch at this time. Mostly cloudy skies are expected for Thursday with scattered showers and highs mostly in the low to upper 60s, warmer further west, with slightly drier and sunnier conditions for Friday allowing temperatures to warm into the 70s away from the coast.


Next Weekend - Early Next Week: More Rain, Possible Cool Down

By next weekend, strong ridging is expected to expand north into Canada across western North America, resulting in a strong trough digging south into the north central US while another cold front tracks through the Great Lakes and Northeast regions, producing more clouds and showers with highs likely remaining in the 60s to possibly low 70s. At this time, the overall model consensus is for a wet Saturday, although some clear the front fast enough for Sunday to end up dry. Assuming the latest models are correct with the handling of the pattern, this front would be followed by a relatively strong trough for this time of the year with 850mb temperatures possibly dropping to near or below 0C, which if verifies would still keep highs in the 60s but with overnight lows possibly falling into the 30s inland.

Based on the overall setup, widespread showers do appear likely for Saturday at this time and possible for Sunday, especially early in the day, although given that this is nearly a week away the timing is still subject to change. There is uncertainty regarding the magnitude of the possible early week cool down, although temperatures are likely to cool down behind the front with early thinking for highs in the 60s and lows in the 40s. Stay tuned for more information on the longer range outlook.