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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 

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 

Steven Copertino

Wide Variety of Impacts Likely From Weekend Storm, Warmer Weather On Borrowed Time

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Good evening! 

Today has been another in a series of relatively warm days when compared to the sub-freezing ice-box that the Northeast was stuck in over the past two week. High pressure has been moving off the coast throughout the day today, leaving most of the Northeast with southeasterly winds at the surface which helped to bring in slightly above-normal temperatures for this time of year. Highs were able to reach into the upper 30’s to middle 40’s across much of the NYC metro area this afternoon, with middle to upper 30’s over much of the Lower Hudson Valley. Today started off rather clear, but westerly winds in the mid levels of the atmosphere allowed for some weak mid level energy to pass over the Northeast. This weak mid level energy helped to bring some increasing mid level clouds this afternoon, which likely capped off our high temperatures for the day. As we head later into the evening and the overnight hours tonight, this mid level energy is expected to clear out as the area of high pressure centered off the Mid Atlantic coast begins to head off to sea. This will allow for mid level flow to strengthen from the south and west, which should bring in increasingly warmer mid level temperatures this evening. We may see the early evening temps become our overnight lows as most of the I-95 corridor may warm up a few degrees during the overnight hours. Regardless, lows will likely be in the lower to middle 30’s across the Lower Hudson Valley, with locations in and south of NYC likely getting into the middle to upper 30’s. It may not be all that impossible to see some locations in central and southern New Jersey to see temperatures rise into the 40’s during the overnight hours.

This evenings surface observations, RTMA 2 meter temperatures, and regional radar mosaic showing a rather dreary and cool day across the Northeast with warmer temperatures off to the west

This evenings surface observations, RTMA 2 meter temperatures, and regional radar mosaic showing a rather dreary and cool day across the Northeast with warmer temperatures off to the west

Thursday is likely to start off rather cloudy and cool as winds from the Atlantic continue to bring in a moderately moist airmass in the mid levels. These clouds and even some spots of patchy drizzle will likely continue throughout the majority of the day as a large system centered in the plains continues to drag a more moist/warm airmass over the Mid Atlantic and Northeastern States.  Widespread cloudiness through the lower to upper levels should allow highs to rise into the upper 40’s to lower 50’s across much of the area tomorrow, with some locations to the south of NYC likely getting into the lower 50’s. Very strong southerly flow should become well established by the evening and overnight hours, and we may once again see temperatures rise a bit into the upper 40’s and lower 50’s. Moisture content in the atmosphere will also begin to rise rather rapidly ahead of a frontal system over the Ohio Valley, which may begin to kick off some light to moderate rain showers over much of the Mid Atlantic and Northeast.

Friday morning will almost certainly start off very warm and cloudy, with the threat for some steady rain, especially as you head further west into western NJ and PA.  As the front gets closer to the Northeast during the afternoon hours, there will be much more available lift in the atmosphere to support more moderate to heavy rain. Moisture content will also be very high (PWATS around 1.4″) for this time of year, so some of the heavier areas of rain may be capable of very heavy downpours that may cause some street flooding. This flooding threat will also be exacerbated by the amount of snow left over the area, with the greatest risk for street flooding in more urban locations with poor drainage. Some of the higher resolution models are also indicating the potential for some thunderstorms to exist, as some very marginal instability looks to be in place around 11am-2pm. Steady rain is likely for the remainder of the day, with the heaviest rain likely occurring over portions of eastern NJ, LI, and CT. Temperatures will be very warm on Friday, with highs likely reaching well into the upper 50’s! This will further help to melt any leftover snow, which will compound any potential flash flooding.

This afternoons NAM model showing the potential for periods of very heavy rainfall over the East on Friday and Saturday

This afternoons NAM model showing the potential for periods of very heavy rainfall over the East on Friday and Saturday

Myriad of Impacts Likely on Saturday

Low pressure will be tracking from the Tennessee valley and into the Mid Atlantic states on Friday evening and into the overnight hours as a large Arctic high pressure system extends from the northern Plain and into portions of southeast Canada. By early Saturday morning the low will likely be located over the Mid Atlantic states, with a large area of moderate to heavy precipitation over the Northeast. This part of the forecast becomes tricky, as some of our more reliable models have been trending weaker and further southeast with this area of low pressure on Saturday. This is very important detail to nail-down in the 24 hours, as the Arctic high pressure extension will be capable of bleeding sub-freezing air into the Northeast, and this could lead to a significant amount of Saturdays precipitation being frozen for portions of New England and potentially locations further south.

If this system is weaker and further south and east, we may see heavy rain over NJ, LI, CT, and eastern New England, with heavy snow over portions of PA, upstate NY and VT/NH. This afternoons European model showed a similar scenario, but with a significant amount of freezing rain and sleet over portions of PA/NJ, extending all the way north and east into Maine. This type of scenario certainly seems possible at the moment, and we may see the NWS issue Winter Weather Advisories or even Winter Storm Warnings in the next 24-36 hours over portions of the Northeast if this trend continues in tonight’s model runs. Computer models often have a tendency to under-model cold air in the low levels of the atmosphere, which is why we are suggesting that you keep a very close eye on the NWS over the next couple of days, as this would be a potentially dangerous situation for portions of the Northeast. Regardless, more heavy rain would be likely on the eastern side of this low, with the brunt of the rain falling once again over eastern NJ, Long Island, and Connecticut. Rainfall totals in that area may reach amounts of 3″ to locally 5″ in some spots, with a general 1-3″ likely for the rest of the region.

Another hazard we must mention will be the potential for a “Flash Freeze” on Saturday as the Arctic front moves through the Northeast. Temps will quite rapidly fall from the middle to upper 50’s in the early morning hours of Saturday, to below-freezing Saturday night. Any residual rain on roadways will freeze quite quickly and could lead to very slippery conditions, with some spots of black ice. This threat does seem more likely as this time, as the Arctic front is almost a guarantee to quickly move from west to east on Saturday. However, we will be very closely monitoring this potentially dangerous storm over the next few days and will continue to provide updates!

This afternoons European model showing a very wide range of impacts on Saturday with the potential for heavy snow, ice, and potentially flooding rains over the Northeast.

This afternoons European model showing a very wide range of impacts on Saturday with the potential for heavy snow, ice, and potentially flooding rains over the Northeast.

Have a great night!

 

Steve Copertino 

Steven Copertino

Warmer Conditions Finally Take Hold, Watching This Weekend

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Good Evening! 

Today has been quite the interesting day, as we finally saw high temperatures lift above freezing for the first time in almost two weeks for some locations! Many states across the Eastern third of the country saw their coldest first week of January on record, which is a fitting way to bookend this intense Arctic Outbreak that will likely be remembered for years to come. Although some locations to the south and east of the immediate NYC area saw a return to above-freezing, many locations did not and were once again stuck in the middle to upper 20’s. This combinations led to problems, as a weak mid level disturbance moved in from the Ohio Valley this afternoon and brought a mixed bag of precipitation for the majority of the Mid Atlantic and some Northeastern states. Despite having mid level temperatures just slightly above freezing in the lowest 3,000-4000 feet of the atmosphere, low level temperatures were cold enough and were accompanied by enough dry air to have precipitation start off as a mix of freezing rain and sleet for locations mainly to the north of Philadelphia. As this system quickly headed towards the coast during the late afternoon, we were able to see a change to mainly sleet and snow as mid levels once again cooled enough to end the freezing rain threat. Farther south, the freezing rain threat has stuck around longer due to more stubborn mid level warm air and higher temperatures near the surface. No major ice accumulations have been recorded as of this evening, but it would appear that at least some roads have become slick over the past few hours over southern NJ, southeast PA, and portions of MD/DE.

These slippery conditions accompanied by lingering light freezing rain should continue until around 11pm-1am before completely shutting down as dry air begins to take over the mid levels from northwest to southeast. While precipitation may not be all that heavy, freezing rain accumulates the most when rates are light, so please use caution when driving this  evening, especially on back-roads and roads that usually are not treated. Otherwise, we should see continued gradual clearing through the overnight hours, with temperatures getting into the lower to upper 20’s over the majority of the Northeast.

This evenings regional radar mosaic, surface observations, and RTMA 2m temperatures showing some light rain, snow, and freezing rain over the Mid Atlantic states.

This evenings regional radar mosaic, surface observations, and RTMA 2m temperatures showing some light rain, snow, and freezing rain over the Mid Atlantic states.

Tuesday Into Thursday 

Any mid to upper level clouds associated with tonight’s system should be out of the region and well off the coast in time for the morning commute on Tuesday. Tomorrow will likely start off quite cool, but clear for the entire area. Winds should generally be from the west for the vast majority of the day tomorrow, with temperatures likely getting into the middle to upper 30’s across much of the area tomorrow, with only locations north of southern New England staying below freezing. Calm conditions can be expected tomorrow as a surface high pressure system builds in over the Northeast by tomorrow evening. Conditions will be quite calm and just right for some good radiational cooling to take place tomorrow night, which should bring lows down into the lower to middle 20’s right around the NYC metro area, with teens likely to the north and west.

Wednesday should see much of the same, with a high pressure system remaining in control of the weather for the day. Mid level temperatures will begin to rise from the southwest during the afternoon hours, and with relatively clear skies, we should see highs mainly in the middle to upper 30’s, with some locations to the south and east likely getting into the 40’s. Clouds should begin to increase during the late evening hours and into the night as a mid level warm front will begin to lift over the region, bringing warmer temperatures in overnight. Lows will likely range in the middle to upper 30’s, with some locations to the north and west stuck in the low 30’s.

Thursday will likely be one of the more noticeably warmer days as low to mid level flow continues to increase and draw up warmer temperatures in the process. A growing system located in the Plains that will impact our area this weekend should provide some moisture early in the morning hours and possibly into the early afternoon, but these should generally be light in nature as the bulk of the lift associated with the system remains a great distance away. High temperatures on Thursday are going to be tricky, but the increased humidity and mid level temperatures should yield highs in the lower to middle 40’s across much of the Northeast, with some locations likely to hit that 50-degree mark . Any meaningful precipitation looks to wait until the early morning hours of Friday to move in, so expect relatively dry conditions until that time.

18z NAM models evolution of the surface temperatures over the Northeast, showing a change to a warmer couple of days.

18z NAM models evolution of the surface temperatures over the Northeast, showing a change to a warmer couple of days.

Plain Rain Or A Mix For The Weekend? 

Finally, a large area of energy will be over the southern Plains states by Friday morning, and this will help to pump copious amounts of low level moisture into the East during the day. As of right now, it appears that we may see one heavy burst of rain start to move from the south and over the Mid Atlantic and Northeast early Friday morning and into the afternoon hours. Rain intensity may dwindle a bit in the late afternoon hours and into the evening, but at least some showers are likely during this time. The next batch of steady rain looks to occur right around Saturday morning as the mid level energy begins to strengthen and take on more of a negative tilt over the central US. This kind of setup promotes the development of a primary low pressure system over the Ohio Valley, with moderate precip extending from Illinois from Boston. This will be a large system in nature, so the impacts will already be large, however this afternoons European model has shown a more interesting solution as the surface low pressure system bumps into a strong area of Arctic high pressure located over southern Canada. Such a solution would create the threat for snow/sleet/freezing rain as the more dense cold air runs into the strong warm air advection from the south.

As of this evening, it appears that portions of New England would be at greatest risk from any significant frozen precipitation, but this is still five days out at this moment, and these situations usually continue to change up until the event is occurring. We will be closely monitoring the potential for heavy rain and possibly some frozen precipitation this weekend and will provide numerous updates over the next couple of days!

This afternoons ECMWF model showing a large winter storm centered over the Ohio Valley bringing a wide range of possible impacts.

This afternoons ECMWF model showing a large winter storm centered over the Ohio Valley bringing a wide range of possible impacts.

Have a great evening!

Steve Copertino