Aug 6, 2013: Rain Expected For Thu-Fri

Forecast Highlights:

northeast6The trough that was in place over the last few days continues to gradually lift out of the region, giving way to a warm front slowly approaching from the southwest, spreading in more clouds and showers with a relatively warm, moist and humid air mass behind it. Rain and thunderstorms are likely on Thursday through Saturday morning as a frontal system affects the region; a brief spike in temperatures is expected on Saturday, but otherwise temperatures will generally remain near to below average.




Monday, August 5 Observations:

8.5.13 - CopyA trough was in place over the region with a building high pressure resulting in mostly sunny skies and cooler than average temperatures. Morning temperatures fell into the 50s away from NYC and the coast, getting as low as 49 degrees in Sussex, NJ, while Central Park fell just short of the 50s with a low of 62. Daytime temperatures were cooler than average as well, peaking in the mid 70s to near 80 degrees across the area, peaking at 80 degrees in Newark and JFK. The coolest high temperature was 75 degrees in Danbury, CT and White Plains, NY.

Records set/tied on Monday, August 5:

Islip, NY – low temperature
59 degrees (tied record: 59 degrees – 1992)



Today – Wednesday: Clouds Increase, Showers Approach

A trough that has been in place over the last few days, providing cooler than average temperatures to the Northeast region, is gradually lifting out of the region as a strong upper level low in central Canada, blocked by ridging to its north and west, will dive south towards the Great Lakes region, setting up for a more westerly flow aloft. In the surface, yesterday’s high pressure will continue to shift east and offshore, with a SW flow developing, bringing a warm front slowly towards the area with a warmer, moist and humid air mass behind it.

This warm front will remain far enough to the southwest to keep partly sunny skies in the area today with a light SSE wind, as highs reach the upper 70s to low 80s for most locations and the mid 70s in eastern coastal areas. Based on latest indications, the warm front is now likely to be slower than originally expected, which should allow for partial sunshine from NYC and further east on Wednesday while showers remain limited to western parts of the area. With the clouds and rain, western locations should reach the mid 70s for highs, while the rest of the area reaches the upper 70s to near 80 degrees.

Thursday – Friday: Rain, Heavy At Times

With the aforementioned slow trend with the warm front, heavy rain appears less likely on Wednesday night, with the model guidance trending towards scattered showers and thunderstorms overnight, some which may be locally heavy north of NYC but with rain totals generally under 1/4 to 1/2 inch. The rain forecast and probabilities have been accordingly adjusted downwards in the 5-day forecast which will be posted later today, especially east of western NJ/SE NY. The warm front is expected to move through on Thursday morning with the cold front then slowly approaching, with rain and thunderstorm activity likely to be focused on Thursday during the day; an increase in moisture is expected with precipitable water amounts near/slightly over 2 inches, while the front slows down, keeping occasional rain and thunderstorms, possibly heavy, on Friday and Friday night as well. High temperatures are expected to be cooler as a result of the rain, peaking in the upper 70s to low 80s across most of the area, but with overnight lows warming up into the mid 60s to low 70s. Rain totals are more uncertain; at this time, totals of 3/4 to 1.5 inch are likely across most of the area, locally up to/over 2 inches, but are subject to some changes.

Saturday – Next Week: Drier, Slightly Cooler Than Average

The cold front will slowly push through on Saturday, although the strong upper level low will lift north into Canada with the trough flattening as it approaches the area, slowing the front down. At this time, it is likely to clear the area on Saturday to result in partly sunny skies and highs in the mid to upper 80s, possibly reaching 90 degrees for some, although it is possible that the front is slower to move through than currently expected, in which case scattered storms may persist into Saturday with high temperatures a few degrees cooler. With the trough then starting to lift north, the frontal boundary is expected to stall south of the area for Sunday and Monday with temperatures slightly cooler than average, peaking in the upper 70s to low 80s across most of the area.

A weak, relatively broad area of high pressure is likely to cover the region by early-mid next week, which at this time is likely to extend dry conditions through Tuesday or Wednesday, but with models indicating the next storm system may approach by mid-late next week. The pattern overall continues to indicate temperatures near to slightly below average, with no heat in sight through the foreseeable range.



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