April 18, 2012: Moderate Rain This Weekend

Forecast Highlights:

– Next rain event expected between Saturday-Monday
– Moderate rain expected Sat-Sun; Sun-Mon storm still uncertain


Today started out with partly to mostly cloudy skies across the area, although an area of showers in the Mid Atlantic unexpectedly crawled north into the area, resulting in cloudy skies for the rest of the day along with occasional light rain showers. Although skies will clear again for Thursday and Friday, the dry conditions will not last for long as the next rainstorm arrives on Saturday.

Thursday – Friday: Partly Cloudy, Mild

Clearing skies are expected tomorrow with SW winds and a warmer air mass, resulting in temperatures warming up into the upper 60s to lower 70s across the area. Partly cloudy skies will return again for Friday but with a SSE wind, keeping temperatures in the upper 60s to mid 70s from NYC and further north/west and the mid 60s to lower 70s in Long Island/southern CT.

Saturday – Monday: Rain Expected, Uncertainty With Scenario

By Saturday, a cold front will approach the area, with showers and thunderstorms likely towards the second half of the day, especially by the evening and overnight. The model guidance is still split regarding the next step, with the CMC bringing a coastal low right up the cold front along I-95, the 0z ECM was an amplified outlier taking the low pressure through Pennsylvania, the 12z ECM amplifies the coastal low resulting in snow for parts of the area, and the GFS is much weaker, bringing the cold front through with very little rain from the Sunday-Monday coastal low. As a result, it is difficult to make any high confidence forecast at this time when it comes to the Sunday-Monday coastal low potential; some models suggest that as much as 2-4 inches of rain may be possible, while at the same time it is possible that the low doesn’t organize significantly and keeps most of the rain east of the area.

Given some models’ bias of exaggerating amplification of storms, I am considering the 0z ECM and UKMET as outliers. At this time, my thoughts have not changed much, and I am still thinking that a somewhat more progressive storm moves up the coast, with moderate rain and possibly thunderstorms associated with the cold front on Saturday, followed by some more rain on Sunday into Sunday night and possibly Monday associated with the potential coastal low. As previously mentioned, however, there is still uncertainty regarding the development of the coastal low, and this forecast is still subject to change. Stay tuned for more information on this time frame.

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