Dec 2, 2013: Multiple Storm Potentials Starting Thursday

Forecast Highlights:

gfs_namer_096_850_temp_mslp_precipThe first few days of December will start out with a flashback to the last 2 years, with warmer than average temperatures reaching the 50s for highs. This will be short lived, however, as unlike the last 2 years, this December will actually feature a quick transition to a wintry pattern as cold expands across most of the US, with multiple waves of rain expected for the second half of this week and another potential storm early next week (Image credit: NCEP MAG).




Today – Wednesday Night: Warmer Than Average, Showers Weds Night

Despite a frigid ending to November, December started out with more fall-like conditions as temperatures warmed up into the 40s yesterday with light morning showers east of NYC, starting off as freezing rain in interior Connecticut. A coastal low pressure is expected to develop to the east of the area tonight; originally, some of the model guidance had this further west, bringing rain to eastern parts of the area, although this is no longer expected. Mostly cloudy skies will continue today with highs in the mid-upper 40s inland and upper 40s-low 50s for the rest of the area, with slightly less cloud cover on Tuesday with a light NW wind and temperatures slightly warming up. As a cold front approaches the region, which will be discussed in the next section, cloud cover will increase on Wednesday with highs reaching the low 50s for most of the area, along with scattered overnight showers, primarily north of NYC.


Thursday – Friday: Frontal Boundary Slides Through, Rain Expected

The major national weather highlight this week is the arctic air mass surging into the north central and NW US, with a surface low pressure intensifying as it moves through the Great Lakes and towards the Hudson Bay. This will push a frontal boundary towards the eastern US, but as the low pressure stalls near the Hudson Bay and ridging aloft persists over the southeastern US with persistent troughing in the western US, the frontal boundary will significantly slow down with two waves of low pressures expected to move through before the boundary entirely slides offshore.

Thursday is expected to be mostly cloudy with highs likely to reach the low to mid 50s across the area, with the first wave of precipitation moving through on Thursday night; this is expected to be in the form of light to moderate rain, with the possibility for up to 1/2 inch. Initially, the area is still expected to be in the warm sector, keeping temperatures mostly in the 40s overnight, with the frontal boundary likely pushing through during Friday, with a change to NW winds. Mostly cloudy to cloudy skies are expected on Friday with isolated showers and highs likely ranging from the low-mid 40s inland to the low 50s east of NYC. The second wave of precipitation is expected to move through on Friday night; there is some uncertainty regarding the exact placement and timing, although this wave is likely to produce mostly rain for the area as well, with up to or over 1/2 inch possible. With the second wave, however, the possibility is there for snow at the end towards interior NW NJ/SE NY. There remains some uncertainty with the Thursday-Friday outlook, and some changes are possible over the next few days.


Saturday – Next Week: Colder Weekend, Possible Early Week Storm

With the frontal boundary shifting south by the weekend, a colder air mass will enter the region; while temperatures will not be as cold as late November or nearly as cold as the rest of the western US during the upcoming arctic cold surge, temperatures are still expected to fall below average, with highs likely ranging from the mid-upper 30s inland to the upper 30s-low 40s for the rest of the area; dry conditions and less cloud cover will briefly return for the weekend as a strong high pressure builds into the region from the west.

The next area of uncertainty is towards Sunday night into Monday, when some of the models indicate the next potential storm affecting the region. Unlike the late week frontal boundary, in this time period there will be cold air initially in place, and with the strong high pressure in the Northeast, should a storm track into the region in this time frame as currently modeled, there would be enhanced probabilities for front end frozen precipitation, either in the form of snow or sleet/freezing rain. As should be expected for the 7-day range, however, there remains uncertainty regarding the exact track and storm setup; with persistent ridging in the southeastern US, any strong and amplified storm will track inland, with a lower probability and shorter duration of front end frozen precipitation, with a weaker and flatter storm more likely to produce widespread frozen precipitation. For today’s 8-day forecast, I included a chance of snow/sleet for most of the area at the start of the storm before a changeover to rain, although this is a preliminary outlook subject to change over the next few days as details become clearer. Behind this storm potential, colder temperatures are likely towards the middle of next week with a warm up by the late week.


<< November 28 | Nov 29 – Dec 1 | December 2 >>

Sunday, December 1 Observations:

12.1.13In a somewhat similar temperature trend to 2012, the meteorological winter of 2013-14 started with more fall-like conditions as the anomalous cold air mass exited the area in the morning after light freezing rain fell across portions of interior Connecticut. Partial cloud cover was observed with temperatures surging into the mid-upper 40s inland and upper 40s-low 50s for the rest of the area. The highest temperature was 54 degrees in Westhampton Beach, NY, and the coolest high temperature was 41 degrees in Port Jervis, NY and Meriden, CT.


Saturday, November 30 Observations:

11.30.13Cloud cover increased during the day and especially towards the overnight hours as the cold air mass that was in place gradually departed with scattered precipitation approaching the area by the overnight hours. Temperatures initially peaked in the afternoon in the low-mid 30s inland and mid-upper 30s for the rest of the area, but with cloudy skies and light south winds overnight, temperatures quickly warmed into the low-mid 40s in Long Island and coastal CT by midnight, while locations just inland in CT and across most of northern NJ and SE NY remained in the mid 20s to mid 30s. The highest temperature was 44 degrees in JFK airport, and the coolest high temperature was 31 degrees in Montgomery, NY.


Friday, November 29 Observations:

11.29.13The cold air mass that entered on Thursday continued to slightly moderate, with another mostly sunny day and temperatures slightly warming up into the mid-upper 30s inland and upper 30s-low 40s further south and near the coast, but remained nearly 10 degrees colder than average. Lighter winds were observed compared with Thursday as well. The highest temperature was 41 degrees in Newark, NJ and JFK airport, and the coolest high temperature was 34 degrees in Yorktown Heights, NY.

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