July 23, 2013: Drier, Cooler Weds-Friday

Forecast Highlights:

2038A developing wave of low pressure produced widespread rain and thunderstorms to the north and west of NYC, where amounts of 1 to 2 inches of rain were observed, locally higher. Scattered storms will continue this evening, with drier conditions returning starting tonight as the front slowly moves through, bringing cooler than average temperatures into the region for the late week before temperatures slightly warm up ahead of the next frontal system on Sunday into early next week.



Monday, July 22 Observations:

7.22.13 - CopyThe weak frontal boundary that ended the heat wave stalled over Pennsylvania into NYC, while showers and thunderstorms developed in the early afternoon, becoming more widespread and heavier throughout the afternoon and evening hours. The heaviest rain fell from NYC and further north/west with at least 3/4 to 1.5 inch of rain, locally as high as 2-3 inches especially in Morris county, while little rain fell in Long Island and south CT. Highs were cooler as well, only peaking in the low to mid 80s in southern CT/Long Island and the mid to upper 80s for the rest of the area. For the first time since July 13, no NWS station in the area reached 90 degrees.

Tonight – Saturday: Drier And Cooler Weather Returns

2038As the latest radar image shows to the left, scattered thunderstorms are currently affecting locations north and west of NYC. These storms are relatively weak and fast moving, but are still capable of producing briefly heavy rainfall with up to 1/4 to 1/2 inch, locally higher. Temperatures tonight will remain relatively mild, in the mid 60s to low 70s across the area. The cold front will continue to slowly move east, crossing the area on Wednesday morning with little to no rain expected from the frontal passage. Behind the front, an unseasonably cool air mass will enter the region, bringing the most significant break from the warm and humid conditions since mid June to the region. The front will be blocked from progressing further offshore with strong stationary ridging in the central Atlantic Ocean, keeping the boundary offshore as a wave of low pressure develops to the east on Friday, moving north while brushing eastern New England on Saturday. This setup is expected to keep dry and cooler than average conditions over the region in the Thursday-Saturday time frame.

With the front moving through on Wednesday, a west-NW wind is expected with partly sunny skies and highs reaching the upper 70s to low 80s inland and the low to mid 80s for the rest of the area. Cooler than average overnight lows are expected, falling into the low to mid 50s inland and the mid 50s to low 60s for the rest of the area except for NYC and coastal Long Island, in the low to mid 60s. Mostly to partly sunny skies are expected to continue into Thursday and Friday with highs slowly warming up into the low to mid 80s for most of the area with mid 80s near NYC and northeast NJ, while overnight lows slowly warm into the upper 50s to mid 60s away from NYC and the coast. Temperatures are likely to return to near average on Saturday with highs in the mid to possibly upper 80s.

Sunday – Next Week: Cold Front Approaches, More Storms

A slow moving upper level low is expected to track east through southern Canada during the weekend, later tracking northeast, with its associated cold front slowly moving into the region. This setup is expected to produce another round of scattered showers and thunderstorms across the region on Sunday and Monday, possibly including Tuesday as well depending on the timing of the front. With high precipitable water values, storms may be capable of producing heavy rainfall across the region, especially to the north and west of NYC. Drier conditions are likely to return towards the middle of next week with temperatures generally remaining near average.

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