Sept 2, 2012: Cloudy, Rainy Week Ahead

Forecast Highlights:

– Rain, clouds from Isaac’s remnants to slowly spread in
– Frequent rain, mainly cloudy skies expected this week
– Heavy rain a risk on Tuesday-Wednesday; 1-2″+ likely
– Cooler temps return, back in the 70s to low 80s for highs


Saturday, September 1 Observations:

Another hot day was observed across the area as the cold front moved through, although the model guidance suppressed the warm air mass more than actually observed, resulting in noticeably warmer than expected temperatures. Highs reached the mid to upper 80s across most of the area with lower 90s in most of northern NJ and the immediate NYC area. The hottest temperature was 92 degrees, tied with Teterboro, Newark and JFK.

Sunday, September 2 Observations:

Following the heat surge on Friday and Saturday, cooler temperatures returned as the warm air mass weakened and cloud cover from the remnants of hurricane Isaac spread into the region. Mostly cloudy skies were generally observed with isolated showers and thunderstorms, notably at night from Westchester into Rockland and Bergen counties, where a slow moving storm cell dumped locally near/over 2 inches of rain.

High temperatures were in the upper 70s to lower 80s across the area. The warmest high was 85 degrees in Montgomery, NY.

Week Ahead: Cloudy, Rainy, Cooler

Isaac’s remnants slowly drifted through the central US over the last few days, producing widespread flooding along with severe weather and some tornadoes. While Isaac’s remnants will no longer produce severe weather outbreaks when reaching the region, Isaac’s remnants will deliver widespread moisture into the region with precipitable water values above 2 inches, resulting in a heavy rain potential this week.

A wave of low pressure associated with the remnant of Isaac will move through the region on Tuesday and Wednesday, producing a round of heavy rain. For Monday, mainly cloudy skies are expected with a few breaks in the cloud cover along with scattered showers/storms. More widespread storms are expected late on on Monday night into Thursday and the first half of Wednesday, when heavy thunderstorms are expected, especially during Tuesday night. Widespread rain totals above 1-2 inches are expected, perhaps getting as high as locally 3-5 inches in a few spots. Flash flooding is a concern with the heavy rainfall associated with Isaac’s remnants. Cooler temperatures are expected due to the cloud cover and rain, generally in the mid to upper 70s in Long Island/S CT and upper 70s-low 80s for NYC and north/west, slightly cooler on Tuesday.

Less storms are expected for Thursday with the wave of low pressure moving out, although another cold front will approach the region afterwards. There is more uncertainty with this time frame, as a cold front is expected to move through around Friday, with a much drier frontal passage compared to the mid week storms associated with Isaac, although a trough is then expected to drop into the central US, likely to split from the main flow but with the location still uncertain. The ECM forms a cutoff low over the western Ohio Valley, while the GFS does so over the region. Drier conditions are likely for Friday through Sunday, with a risk of scattered showers/storms but with widespread rain unlikely at this time, with temperatures generally likely to end up in the upper 70s to low 80s for most places. Stay tuned for more information on the heavy rain this week and the potential rain early next week.

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