Steven Copertino

Snowstorm Exits, Warmer Conditions Ahead Next Week

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Good Evening! 

The snowstorm that we have been discussing for the past week has finally exited the region after dropping light to moderate snow for most locations. Due to onshore flow, precipitation mainly started out as rain over portions of New Jersey and southern New York, but colder air associated with the frontal system over Pennsylvania gradually made its way south. This caused the rain to flip to snow over much of the area, with coastal sections of New Jersey and Connecticut seeing plain rain. Rain was also quite common over the majority of Long Island this afternoon, as winds from the east kept temperatures in the middle to upper 30’s. Snow totals around the New York city metro area were generally light with a trace to three inches common for most locations. Totals over the southern half of New York state were a bit higher, with 6-10″ being reported due to snow from the frontal system as well as the weak coastal low. All major NYC airports reported less than one inch of snow as of 4pm, so travel likely will not be impacted all that much tonight.

This evenings latest RTMA 2m temperature analysis, surface observations, and regional radar mosaic showing the snowstorm exiting off the coast

This evenings latest RTMA 2m temperature analysis, surface observations, and regional radar mosaic showing the snowstorm exiting off the coast

Conditions this evening and into the overnight hours will be generally calm as drier air begins to work in at all levels of the atmosphere. This should pretty much kill any chance of residual snow showers, but there could be a brief flurry or two mainly to the north of NYC. Winds will begin to increase from the north and northwest as another coastal low begins to strengthen well to our south. This system will have absolutely no impact on our weather this evening outside of some occasionally gusty winds. The northwesterly flow in the mid levels of the atmosphere combined with the fresh snow pack over much of the Northeast will lead to some pretty cold temperatures overnight, with lows getting down into the upper teens and low 20’s across the immediate NYC area, with locations to the north and west likely seeing lows well into the teens and single digits. This will cause a chance for some of the snow that melted this afternoon to quickly refreeze on untreated roads, so please use caution when traveling.

 

Snow totals from around the immediate NYC area courtesy of the NWS in Upton, NY

Snow totals from around the immediate NYC area courtesy of the NWS in Upton, NY

Warmer and Calm Conditions Through the Weekend

Thursday will be the last cold day across the Northeast for a bit of time as mid level ridging begins to build quite a bit over the central part of the United States tomorrow. Highs will likely remain below freezing during the day, with readings staying in the middle to upper 20’s for northern locations, with lower to middle 30’s possible south of New York City. A weak shortwave trough looks to pass through portions of southern Canada by

Friday afternoon, and this could spark some light snow over portions of northern New England, mainly over ski country. Otherwise, mid level flow from the west should cause temperatures to rise quite a bit, with locations south of New England seeing highs into the 40’s. Conditions will likely remain pretty quiet for the end of the work week south of New England as well as zonal flow begins to setup in the mid levels of the atmosphere.

Mid level heights will rise substantially on Saturday morning, leading to a mainly calm and warmer day. Temperatures should be able to reach into the lower to middle 40’s during the day, with some locations south of the city likely getting into the 50’s! These temperatures will be quite a bit above-normal for the middle of winter, so enjoy them while they last!

More dry and warm conditions are expected to hold on for Sunday as a large storm begins to gather over the Rocky Mountains that will likely impact us early next week. Regardless, temperatures should be in the middle to upper 40’s once again, with mainly clear conditions expected, making it another great day to get some things done outside like getting rid of the last of the holiday decorations!

This afternoons NAM model showing a drastic change in mid level temperatures over the East during the next three days

This afternoons NAM model showing a drastic change in mid level temperatures over the East during the next three days

Large Plains Snowstorm and What It Means For Us

A large trough will be digging deep into the Rockies and southern Plains by Sunday night, which will trigger a surface low to develop over portions of Kansas and Nebraska. This system will have rich tropical moisture feeding into it from the Gulf of Mexico and as a result, a very expansive area of precipitation will fan out with the help of an impressive upper level jet. Heavy snow will likely fall over the northern Plains, with heavy rain and some thunderstorms likely across the Ozarks and Gulf Coast. This system will likely then begin to weaken a bit, but the strong moisture feed will continue to pump northward as the low moves east towards the Great Lakes. By this time the entire East coast should be in the warm sector of this system, with temperatures likely reaching into the well-above normal category once again. By Tuesday evening, we could be looking at a large cold front moving through the Northeast with associated heavy rainfall and potentially some embedded thunderstorms. There is strong model support for this system almost a week out, but we will certainly be monitoring it over the next few days, so be sure to check back for more updates!

This afternoon European ensembles showing a pretty impressive signal for heavy rain next week across much of the Northeast

This afternoon European ensembles showing a pretty impressive signal for heavy rain next week across much of the Northeast

Have a great night!

 

Steve Copertino 

Miguel Pierre

Morning Snow Winds Down This Afternoon

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Good morning! An inverted trough extending from low pressure offshore has resulted in bands of snow and rain across parts of the Northeast to start the day.  The majority of steady snow so far today has been situated over parts of Northern NJ and the Lower Hudson Valley into Southern New England, where the airmass remains colder and more supportive of precipitation. Closer to the coast, enough warm air from east-southeast winds off the ocean has lead to mainly light rain with some snow mixing in at times.

As low pressure moves further east off the Northeast coast and begins to deepen, it will drag colder air in behind it via northerly winds. Precipitation may end as a period of snow for coastal areas with some light accumulations under 2″. In fact, this is occurring already as of 8am over much of the NYC Metro Area. Any accumulations will likely be relegated to colder surfaces as temperatures remain above freezing.

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John Homenuk

Snowstorm expected tonight across interior Northeast, less near coast

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In the middle of a winter that seems to continually overproduce at the final buzzer comes another storm system, expected to develop late tonight into early Wednesday morning, that is expected to bring moderate snowfall to much of the Northeast states. It is really quite remarkable how many storm systems have trended more wintry in the final moments during the first half of this meteorological winter, and this storms system will be no exception. Occurring during a pattern transition, with warmer air moving in to the Northeast, it will feature challenges in terms of precipitation type.

A weak low pressure system is already in the process of developing off the Southeast US coast this morning. This low pressure area is mainly associated with an offshore baroclinic zone, or temperature gradient, near the Outer Banks of the Carolinas. Increased precipitable water values are noted on observations and forecast soundings, and models suggest this low pressure area will gradually organize later today.

Meanwhile, a deep trough will dig over the Central United States and is expected to amplify through the Mississippi Valley. As it turns towards the coast, and vorticity advection occurs near the coast, lift in the atmosphere will increase along the baroclinic zone and the low pressure system will deepen while heading north/northeastwards towards the Long Island coast. Precipitation is expected to develop to the west of the low pressure, near a frontal boundary, across the Northeast states later tonight.

Upper-level trough digging and amplifying over Eastern US. But the trough remains positively-tilted and more progressive.

The deep trough amplifying over the  Eastern US. But the trough remains positively-tilted, resulting in a more progressive storm system on Wednesday

Initial precipitation will be light, but steady, across parts of Pennsylvania and New England. But as the storm system gains some steam, banding is expected to develop across parts of New Jersey, Southeast New York and Connecticut and spread into New England. Without any prevalent high latitude blocking, the system will remain mostly progressive. But wintry precipitation amounts could still be significant in some areas, particularly across the interior.

One of the biggest forecast challenges tonight will be temperatures. While plenty of cold air exists aloft, forecast models are consistent in suggesting that the boundary layer will remain quite warm. The boundary layer is the low level atmospheric profile — where we live. And if it is warm enough, snowflakes can melt before they reach the ground. With an onshore flow (wind off the water) prior to the storm, models suggest this will be the case for much of Eastern New Jersey, Long Island, and Southeast Connecticut — mostly a cold rain.

Just inland, however, bands of snow are expected later tonight, and the potential exists for several inches of snow. While quick moving, models suggest enough dynamics for moderate snow in these bands, with quick accumulations of 3-6″ and possibly amounts higher than that in the highest elevations of Northwest NJ, Northeast PA, Southeast NY and New England. The winter storm is expected to be moderate impact in these locations, with a lighter impact event in NYC and even lighter along the coastal plain.

Expected Storm Total Snowfall from Tuesday Night/ Wednesday Afternoon

Expected Storm Total Snowfall from tonight through Wednesday Afternoon

The National Weather Service has, accordingly, issued Winter Weather Advisories for many locations. These create a good visual as to where the impacts are most likely and expected. In these regions, plan for winter weather tonight, including 3-6″ of snowfall, and leave extra time for travel through Wednesday morning when the event finally comes to a close.

The good news? Much warmer weather is anticipated over the coming days, with temperatures 10-15 degrees above average by this weekend! More details to come on that — we have a snowstorm to get through first.

Steven Copertino

Light to Moderate Snow Likely Tuesday Into Wednesday

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Good evening! 

Most of the Northeast saw another below-average day as the Arctic high pressure system that has been dominating our weather over the past few days has finally begun to head off to the east over portions of southern Canada. As this high pressure system retreated to the east, we saw wind direction flip to a more easterly/northeasterly, with winds in the mid levels becoming more southwesterly ahead of a large disturbance moving south over the Great Lakes region. These southwesterly winds have aided in providing a slightly warmer airmass aloft, with some weak moisture also working into the low to middle levels of the atmosphere. This allowed the development of some mid to upper level clouds over the Mid Atlantic and Northeast during the afternoon hours, with even some scattered flurries being reported within in a weak band of moisture over portions of Pennsylvania. The combination of slightly warmer mid levels, partly cloudy conditions, and easterly low level flow made for slightly warmer highs when comparing them to the past two days. The immediate NYC metro area saw readings in the upper 20’s to lower 30’s, with locations to the north and wets seeing temperatures in the lower to middle 20’s, which is still around five or so degrees below normal. Generally dry and calm conditions are expected for the rest of the evening and into the overnight hours, with a slight chance of some widely scattered flurries. Temperatures will likely fall back into the lower to middle 20’s across the immediate NYC metro area, with teens expected to the north and west.

This evenings latest look at the regional radar mosaic, surface observations, and RTMA 2m Temperatures, showing a rather chilly evening with a disturbance approach from the west

This evenings latest look at the regional radar mosaic, surface observations, and RTMA 2m Temperatures, showing a rather chilly evening with a disturbance approach from the west

Light-Moderate Snow Event Likely Tuesday Into Wednesday 

This afternoons model guidance has come into slightly better agreement regarding a large closed upper level low centered over the Great Lakes region this evening. This upper level low has been meandering in about the same position for the past 36 hours or so, but this will change tomorrow afternoon as an impressive Pacific disturbance crashes into the West coast. This disturbance will act as a “kicker” for the upper level low in the Great Lakes, and cause it to elongate while becoming positively tilted. As it does so, a large upper level jet will extend from the Southeast Unites States and into the Northeast.  Some weak moisture will be involved in this initial setup, allowing for snow to break out just ahead of a frontal system as the upper level jet provides some adequate lift along the front. This frontal system will be located over the eastern third of the country by tomorrow afternoon, with snow likely forming over much of the Mid Atlantic and Northeast during the late morning and early afternoon hours. Some light snow may work its way into the NYC metro area later in the afternoon, but there may be some rain mixed in closer to the coast as surface temperatures hover at or above freezing.

Simulated Radar showing a potential evolution of the snow event on Tuesday/Wednesday

Simulated Radar showing a potential evolution of the snow event on Tuesday/Wednesday

A weak surface front associated with some more robust moisture from the Atlantic will begin to develop off the Mid Atlantic coast during the late afternoon hours and into the evening on Tuesday. This afternoons models have shown more of the moisture becoming super-imposed with the upper level jet streak aloft, which allows a very weak coastal low to develop off of the Delmarva peninsula by 8-10pm tomorrow night. Depending on the track of this low and the associated moisture plume, we could see more moderate snow develop over eastern PA, MD, VA, SNY, eastern NJ and Connecticut during the overnight hours. Again, precip type may be more wet than white closer to the coast, but we could see a gradual shift to snow during the morning commute for locations to the south and east of NYC. This weak low pressure system will be moving at pretty good clip, so as of now we expect that snow will peak in intensity over the NYC area right around 7-9am before very gradually tapering off from west to east during the afternoon. At this time, we expect generally light accumulations to the south of Northern NJ, with light to moderate accumulations further off to the north and east.

There are some uncertainties that remain with this system, as surface temperatures during the height of the storm may be a little too warm for accumulating snow, and this would cause totals to decrease a bit, especially to the south. Another possibility is that we see the coastal low develop a little quicker than originally thought, which would not only brings in more moisture, but would drag more cold air in from the north. Such a solution would yield higher snow amounts area-wide, but at this time we feel that solution is less likely to happen. However, we will be closely monitoring this system over the next day or so, so make sure to check back for future updates!

Expected Storm Total Snowfall from Tuesday Night/ Wednesday Afternoon

Expected Storm Total Snowfall from Tuesday Night/ Wednesday Afternoon

Have a great night!

 

Steven Copertino