April 14, 2013: Mild Week, Friday Night Thunderstorms

Reminder: The blog will remain in a limited updating schedule through Friday, April 19. Until then, updates will be posted every 2 days.

Forecast Highlights:

Following a seasonable and dry weekend, the weather pattern becomes active again for this coming week, as with last week. Temperatures will warm up into the 60s with a few 70s possible on Wednesday and especially Friday, with scattered showers during the mid-late week until a strong cold front tracks through the region on Friday night, producing rain and thunderstorms followed by a repeat of this weekend with cooler and dry conditions.

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This Week: Warmer, Stormier

In a set-up not too different from last week, a low pressure currently producing a snowstorm in the Midwest will track into Canada, bringing a cold front towards the region while bringing warmer temperatures into the region. The cold front then comes through on Wednesday and Thursday, followed by another storm on Friday that pushes out the warmth. While the overall storm and front timing are somewhat similar to last week, there are more significant changes in the large scale pattern that will result in a different outcome. Unlike last week, however, in this case there is no blocking in northern Canada and a strong upper level low in SE Canada to suppress the late week storm and prevent the frontal boundary from shifting back north, and the contrast between the warmer air mass to the south and colder air to the north is less significant than last week, particularly Wednesday when a significant temperature contrast was found near the boundary.

As a result, the temperature and pattern outlook for this coming week has higher confidence than last week, with the main areas of uncertainty at this time regarding temperatures on Thursday-Friday. The first cold front is expected to move through the region on Tuesday, with the weak frontal boundary then stalling near or just south of the area on Wednesday and Thursday. With a lack of a ULL over SE Canada, the frontal boundary will lift back north on Thursday as a warm front, with widespread warmth expected on Friday as the next low pressure tracks through the Great Lakes, bringing a cold front with rain and thunderstorms through the region.


Forecast for NYC area: Partly sunny skies are expected for Monday with a light ESE wind as highs reach the upper 50s to low 60s from NYC and further north/west and the mid to upper 50s in Long Island and southern CT. Clouds will increase on Tuesday ahead of the cold front as highs reach the mid to upper 60s inland, upper 60s to low 70s in the immediate NYC area, and the low to mid 60s across most of Long Island and southern CT.

The frontal boundary is then expected to shift just south of the area with scattered showers for Tuesday night. Mostly cloudy skies with isolated showers are expected for Wednesday with highs in the mid 60s to low 70s across the area. Similar cloud cover and isolated showers are expected again for Thursday but with cooler temperatures as a SE flow develops; the temperature outlook for Thursday is more uncertain, although at this time highs are likely to reach the low to mid 50s in Long Island/southern CT and the upper 50s to low 60s, possibly mid 60s, from NYC and further north/west.

By Friday, with the warm front well north of the area, a widespread south flow is expected across the region with a warm air mass surging north. While locations east of NYC are likely to reach the 60s, NYC and further north/west is likely to reach the upper 60s to the low, possibly mid 70s. Mostly cloudy skies are still expected with the risk of isolated showers. The cold front is then expected to move through overnight, resulting in rain and thunderstorms which are mostly expected to clear the area by at least Saturday morning or afternoon.


Next Weekend Overview: As with this weekend, a trough is expected to return into the region for next weekend with mostly cloudy skies on Saturday, a risk of showers in the morning, with highs otherwise reaching the mid to upper 50s. Cooler overnight lows are likely again, reaching the 30s away from NYC and the coast, with more sunshine on Sunday and highs again likely in the mid to upper 50s. Temperatures are likely to slightly warm up towards early next week, but unlike the beginning of this upcoming week, no widespread storm is likely over the eastern half of the US.