Yesterday’s snowstorm, having produced snow totals from 1 inch near NYC to as much as 7-8 inches in eastern locations, was only the latest addition to what is one of the snowiest months on record, with 2013-14 now the 8th snowiest winter on record in Central Park. While the peak of the snow has likely passed, this winter’s cold and snow are still not over; 1-3 inches of snow are likely on Tuesday, followed by a temporary late week-weekend warm up only to be followed by a widespread cold surge to close the month.
Tonight – Monday: Still Cold, Few Snow Showers
Posted above from left to right are the latest surface analysis and radar composite from WPC, and the initialized NAM 500 millibar heights and vorticity from NCEP MAG; both are valid at 18z (1pm). Yesterday’s storm, which produced light to moderate snow across the area, has rapidly deepened last night and is now a very deep 964mb low pressure just northeast of Nova Scotia. With the low pressure departing the region, the pressure gradient has decreased, leading to lighter winds compared with last night and this morning, although another feature to note is a weak low pressure over western Pennsylvania associated with a weakening clipper system; most of the precipitation associated with this system is drying out but with mostly cloudy skies to continue with isolated snow showers possible this evening.
The high pressure behind the clipper will build into the region tonight into Monday; a few days ago this high pressure was forecast to be positioned overhead tonight, but with the pattern slower than previously expected, this high will remain west of the area overnight, not moving overhead until during the day on Tuesday. This will keep cloud cover in place for tonight with a decreasing northwesterly winds, which are not ideal conditions for strong radiational cooling as observed last week when interior locations fell below -10 degrees for lows. Temperatures tonight are expected to fall into the upper 0s in interior NW NJ/SE NY, upper 10s in NYC, and the low-mid 10s elsewhere. Mostly sunny skies are expected for Monday with highs in the upper 20s to low 30s.
Tuesday: Snow To Rain, 1-4 Inches Expected
18z GFS at hour 42, valid at 12z Tuesday (7am), depicting light snow covering the area. The low pressure near western NY later transfers to a coastal low with heavier snow near New England (image credit: PSU e-Wall).
The next snowstorm will affect the area late on Monday night into Tuesday afternoon, bringing another round of light to moderate snow accumulations. A strong but relatively flat shortwave trough will race east through the northern US, supporting moderate snow reaching the region on Monday night, developing in the area around 2-4am. As this will be a fairly fast moving system with a southwesterly flow setting up behind it, temperatures will gradually warm up throughout the event, with a changeover to rain likely near Long Island and coastal areas into Tuesday morning before precipitation ends in the late morning or early afternoon. The model guidance has varied regarding the location of the transfer to a coastal low pressure, which will also determine whether the steadier snow rates develop near the area or to the northeast. Yesterday’s models were particularly indicating the former scenario, with the ECMWF supporting as much as 4-6 inches of snow in the area, but with the models having since backed down on precipitation totals. At this time, I am expecting snow accumulations to end up in the 1-3 inch range for most locations, with totals over 3 inches possible northeast of NYC into Connecticut, where totals up to 4-5 inches are possible. The outlook is subject to slight changes over the next day as the model guidance gains a better handle on the development of the low pressure. The snow from this system, albeit relatively minor, will further help to ensure a full month of snow cover for most of the area by Friday, 2/21.
Through today, Central Park has recorded 55.6 inches of snow to date this winter, and 27.3 inches during February. If at least 2.2 inches of snow accumulate on Tuesday, this season will be placed as the 6th snowiest winter on record. The snowiest month on record is February 2010 with 36.9 inches of snow; while this storm alone will not lead to such totals, Central Park is at least 3.5 inches away from the 3rd snowiest month on record, behind February 2010 and January 2011.
Wednesday – Saturday: “February Thaw” Expected, Highs in 50s Possible
With the strong cold air mass having retreated back into northern Canada, along with a more zonal flow in the upper levels, there will be no strong cold air source for the incoming systems to tap into and to pull into the region, which along with the low pressures tracking north of the area leading to a southwesterly flow in the lower levels, the most prolonged warm period since mid January is expected starting on Tuesday with highs in the upper 30s to low 40s following the light snow event. With the upcoming warmer temperatures and rainstorm, along with the deep snow pack currently over 12-18 inches deep for many locations, the potential for flooding exists as the snow pack gradually melts.
Another shortwave will pass through the region on Wednesday but further north than Tuesday’s system, leading to mostly cloudy skies, isolated showers, and high temperatures mostly in the low to mid 40s, possibly reaching the upper 40s near and south of NYC. Slightly cooler temperatures are expected on Thursday in the low to mid 40s along with increasing cloud cover. The next storm system is expected to affect the region on Friday as a deepening low pressure tracks through the Great Lakes into Canada, leading to a surge of warm air from the south and supporting temperatures increasing on Thursday night into at least the mid 40s. A brief spike into the 50s is possible on Thursday morning depending on the timing of the cold front, with a line of moderate rain likely between the morning and early afternoon hours. A slow cool down is expected on Saturday and Sunday with highs still likely in the 40s; the ECMWF currently suggest a moderate rain event on Sunday, although currently it does not have any model support; only the latest 18z GFS run hints at a similar outcome, and while uncertainty remains, a chance of rain has been added for Saturday night.