April 6, 2013: Warmer Pattern Next Week

Forecast Highlights:

A trough briefly moved into the region today, producing widespread cold temperatures this morning, likely the last for a while given the upcoming warmer pattern, with highs slightly cooler than average, peaking in the 50s. A ridge is expected to build into the region with warmer temperatures persistently staying in the 60s and 70s starting on Monday and lasting through the majority of next week until a cold front moves through early on Friday.

Tonight – Sunday: Warming Up

As a trough continues to exit the region with a warm front moving through, temperatures are expected to quickly warm up across the region on Sunday. Partly to mostly cloudy skies are expected with isolated showers possible in the evening hours for interior areas. Highs are expected to reach the upper 50s to low 60s from NYC and further north/west, and the low to mid 50s in Long Island/S CT, with a breezy south wind of 10-20 mph expected.

Next Week’s Outlook: Warmth Expected

With the cold front behind a low pressure to the north on Sunday failing to drop into the area, a warmer pattern will be in place across most of the region starting on Monday, lasting through the majority of next week. Partly sunny skies are expected on Monday with much warmer temperatures, peaking in the upper 60s to low 70s from NYC and further north/west, mid to upper 60s in southern CT and low to mid 60s in Long Island with an expected sea breeze. Another low pressure will track into New England on Tuesday, with scattered showers and possibly some thunder likely north of NYC on Monday night. Following the scattered showers, partly to mostly cloudy skies are expected on Tuesday with temperatures warming up  again, peaking in the mid to upper 60s in Long Island and the low to mid 70s for the rest of the area. In the warmer case scenario, temperatures may reach the upper 70s near the immediate NYC area.

The main area of uncertainty remains the Wednesday-Friday time frame regarding where the frontal boundary sets up. Last night’s discussion noted that while the ECM was the coldest model, it was a complete outlier with how cold temperatures were, with even its ensemble mean much warmer than the operational run. With today’s runs, the GFS and CMC backed away from the amplified eastern US ridge and now keep the storm track over the northern US as opposed to the Hudson Bay, but still keep the frontal boundary north of the area. The ECM has slightly trended north with the boundary, but remains an outlier with keeping it south of the area as every other model, even including its ensemble mean, keep this boundary near or north of the area. These differences are most evident for Thursday; while the GFS and CMC show highs in the 70s to near 80 degrees, the ECM has rain and highs only in the low-mid 40s, an unlikely scenario. While the ECM does typically have higher verification, in this case I am considering it an outlier at this time and siding with the rest of the models keeping the frontal boundary north of the area.

The next question is how far north the frontal boundary sets up, whether it’s near the area or well to the north. The GFS keeps this boundary not far to the north with temperatures generally peaking in the low to mid 70s for Wednesday and Thursday, but the CMC and DGEX show this further north, with highs even reaching the 80s across many locations north and west of NYC. These models usually have lower verification, however, and at this time I am siding with a less warm scenario, although there is a possibility that, should the frontal boundary remain far north enough, temperatures may reach 80 degrees near the immediate NYC area.

Forecast for NYC Area: Assuming that the frontal boundary remains not far north of the area, temperatures are likely to remain in the low to mid 70s west of NYC on Wednesday and Thursday with mid 60s to 70 degrees for the rest of the area. Both days are expected to feature mostly cloudy skies with a risk of showers and/or thunderstorms, although most precipitation is likely to stay north of the area. Wednesday is expected to be the warmest day, with widespread highs in the 70s away from the coast, reaching the upper 70s or even possibly the low 80s in northeast NJ and NYC. The low pressure in the central US will shift into the region by Friday, at this time likely to end up more towards the first half of Friday, producing widespread rain, which will be followed by a cool down for next weekend with highs returning into the 50s.

As previously mentioned, model differences are significant for the longer range, and forecast confidence is moderate at this time. The forecast is subject to some revisions, especially the temperature outlook for Wednesday and Thursday; at this time, I am leaning towards the warmer scenario, although it is possible the ECM may be closer to reality in which case temperatures would be colder than currently forecast. Stay tuned for more information on next week’s outlook.