Dec 11, 2013: Cold Returns, Storm This Weekend

Forecast Highlights:

gfs_namer_072_850_temp_mslp_precipAn active stormy pattern continues across the region, with a widespread 1 to 4 inch snow event having affecting the area yesterday, the 3rd system in 5 days to affect the area with precipitation. Behind the storm, cold temperatures have returned with highs in the 20s-low 30s and lows in the 10s, and will continue for the rest of this week into Saturday, when the next storm is expected to affect the region with additional snow likely, followed by a continuation of cold temperatures into next week (Image credit: NCEP MAG).

 

 


 

Tonight – Friday: Cold Temperatures Continue

Behind yesterday’s wave of low pressure, which produced slightly less snow than forecast, cold temperatures returned into the region today with highs in the low 30s for most locations. As the trough axis moves through the area on Thursday, colder temperatures are expected, only peaking in the mid to upper 20s for highs across most of the area and possibly reaching the low 30s for NYC and coastal areas, with overnight lows falling into the 10s across most locations, with low 20s in NYC and the possibility of sub-10 degree lows for interior NW NJ/SE NY. A slight warm up is expected on Friday with highs in the upper 20s to mid 30s, but remaining firmly below average.

 

Saturday – Sunday: Snow, Sleet, Rain Expected, Amounts Uncertain

The next widespread weather event will affect the area on Saturday into Sunday as several energies interact over the eastern US. A shortwave trough currently over southern California will track northeast towards the Ohio Valley as it flattens out, with a weak low pressure likely to develop near Ohio spreading widespread overrunning snow into the region by Saturday in the early afternoon; the exact location is uncertain but at this time most of New Jersey, Pennsylvania and southern NY states are favored for the snow placement. With strong cold air initially holding well over the area with a strong high pressure to the north, highs on Saturday are only expected to peak in the upper 20s for most with snow forecast across the area during the afternoon and evening hours.

The main uncertainty is towards the overnight hours, as another shortwave trough currently over the northwest US quickly catches up with the system by Saturday evening and a coastal low begins to form off the Delmarva coast. The model guidance has struggled to handle the northern stream and its interaction with the southern stream, with yesterday’s runs depicting a stronger coastal low but today’s runs generally backing down from this scenario, siding with a weak and progressive coastal low that quickly moves out overnight with little additional precipitation, as the northern trough fails to dig as far south and with less favorable alignment of both the north and south streams. This far out, the model guidance typically tends to have some issues handling the exact location and timing of these energies, which in some cases can lead to more changes in the short range; the trend with most recent storms except for late November, however, has been for weaker, further south and drier storms than modeled in the long range, and at this time I am siding towards a similar scenario for the overnight hours with mid level warm air advection leading to a gradual changeover to sleet/ice for interior locations and rain near the coast, but without enough precipitation left over to lead to a significant rain/ice event. This scenario would support at least light to moderate snow accumulations across the area.

As previously noted, there remains uncertainty with the exact setup, and additional changes are still possible. While I am currently siding with a weaker and further south storm, the possibility of a stronger storm cannot be ruled out, which may increase snow totals especially inland but result in more significant interior sleet/ice and coastal rain overnight due to mid level warming. More information will be posted with the next update on Thursday.

 

Monday and Beyond: Behind the storm, temperatures will remain chilly on Monday, with highs in the upper 20s-low 30s and widespread lows in the 10s to low 20s forecast, but with a temporary warm up towards midweek as a weak low pressure likely tracks north of the area with the possibility of isolated to scattered rain/snow showers. Uncertainty increases towards the longer range, but with indications of a break in the cold pattern by next weekend as strong troughing likely returns into the western and central US.


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Tuesday, December 10 Observations:

12.10.13Read more: December 10 Storm Updates

As soon as one storm moved out, the next moved in, with widespread moderate snow during the morning to early afternoon hours. Most locations saw less snow than forecast, generally between 1 and 3 inches, locally up to 4-5 inches in NE NJ and southwestern CT. Temperatures were slightly warmer than forecast over NYC and Long Island, while less precipitation fell than forecast over interior western areas. The highest temperature was 39 degrees in LaGuardia and Montauk, NY, and the coolest high temperature was 32 degrees in Port Jervis, NY and Andover, NJ.

Monday, December 9 Observations:

12.9.13Continuing Sunday night’s storm, light rain continued near NYC and the coast with light freezing rain north and west of NYC and into Connecticut during the early morning hours. As the low pressure moved out during the day, temperatures slightly warmed into the low to mid 30s for most locations north and south of NYC, which was colder than forecast, while Long Island surged into the 40s to low 50s with an easterly wind during the late morning-early afternoon. The highest temperature was 50 degrees in Westhampton Beach, NY and Montauk, NY, and the coolest high temperature was 32 degrees in Port Jervis, NY.

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