April 30, 2013: Pattern To Continue This Week, Next Weekend

Forecast Highlights:

The showers that briefly reached the area yesterday have retreated back to the south earlier today, with clearing skies and temperatures warming up into the 60s. With a high pressure persisting over the region, mostly to partly sunny skies and temperatures near to slightly below average will persist through the rest of the week into the upcoming weekend, with any rain delayed until at least early-mid next week.

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Tonight - Friday: Frost, Warm, Then Cooler

Following yesterday's scattered shower activity, rain mostly stayed to the south today as the high pressure over the region shifted south. Currently, weak ridging covers the Northeast US region, but is expected to quickly expand northeast over the next 2 days to cover eastern Canada with 500mb heights up to 576dm, and a brief warm up is expected on Thursday as 850mb temperatures approach 10C. A shortwave currently near Greenland will dive SSW over the next few days, becoming a closed mid level low while tracking offshore and parallel to the coast, ending up east of Cape Cod on Thursday night and near Bermuda by Friday. As this mid level low passes to the east, a pocket of cooler temperatures aloft, sub-freezing at 850mb to the east, will brush the region, with a weak backdoor cold front moving through on Thursday night, resulting in increased cloud cover and perhaps isolated showers east of NYC followed by cooler temperatures on Friday.

The outlook starts with mostly clear skies for tonight with temperatures dropping into the low-mid 40s in the immediate NYC area and the mid to upper 30s inland, with frost possible especially towards NW NJ, interior SE NY and interior southern CT. For Wednesday, temperatures will warm back up into the upper 60s to low 70s from NYC and further north/west, with LI and coastal CT ending up cooler, in the low to mid 60s, with a persisting east wind. A slightly warmer air mass will move in for Thursday, which combined with mostly sunny skies will allow for warmer temperatures, peaking in the low to mid 70s from NYC and further north/west, including interior CT; as with Wednesday, LI and coastal CT will remain cooler, peaking in the mid to upper 60s. The aforementioned backdoor cold front will cross the area overnight with increased cloud cover and perhaps a few showers east of NYC, with mostly sunny skies on Friday and a stronger east breeze along with cooler temperatures, peaking in the low to mid 60s from NYC and further north/west and the upper 50s to low 60s in LI and coastal CT.


Weekend - Next Week: Sunny/Mild Weekend, Rain Likely Next Week

By Friday and Saturday, with the mid level low passing Bermuda and shifting to the east, as well as a weak trough replacing ridging in southeastern Canada, the ridging over the region will gradually begin to break down, with uncertainty regarding how fast this happens and how far north the ridge ends up. Around the same time, another closed mid level low is expected over the central US producing an unseasonably late snowstorm, with uncertainty regarding its track and how long it takes for it to reach the area. Regarding the ridging, the GFS is currently the fastest to break ridging down, warming the area away from the coast well into the 70s for the weekend into early next week, while the ECM is on the opposite side, with a further north ridge slower to break down, with the central US storm tracking NE towards the Great Lakes, as opposed to the GFS which takes it into the Southeast states. At this time, I am leaning closer to the ECM than the GFS for the medium range outlook; temperatures will warm up over the weekend into early next week but with the most significant warmth remaining well north of the area, followed by rain holding off until at least next Tuesday.

Following the brief Friday cool down, temperatures are expected to warm back up on Saturday into the upper 60s to low 70s from NYC and further north/west and the mid to upper 60s in Long Island/S CT, possibly ending up a few degrees warmer on Sunday and Monday with mostly sunny skies likely to continue. At this time, rain is likely to wait until at least Tuesday which would be accompanied by cooler temperatures, although the timing is still subject to change. Stay tuned for more information on the longer range outlook.