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Steven Copertino

Close Call Tonight, Another Snow Threat Possible Later This Week

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Good Evening!

Today started off with a mix of sun and clouds over much of the Northeast, but quickly turned mostly cloudy as a broad mid level disturbance began to move in from the west. Despite the cloudy conditions, today has been above-normal for this time of year, but still reasonably chilly. Highs were mainly in the upper 30’s to middle 40’s region-wide, as a stale mid level airmass worked into the Northeast. As we move into the late evening and overnight hours, the broad mid level disturbance centered over the Ohio Valley will continue to gradually move eastward. As it does so, it will bring very meager amounts of moisture from the south over portions of the Mid Atlantic and Northeast. If you take a look at the raw radar reflectivity over the Northeast, you may think that most of the region would be under light to moderate rain, however the moisture in place is not deep enough to overcome all of the dry air which is causing most of this precipitation to dissipate before it even reaches the ground. This is the same system that we talked about last week, and since that time the more conservative scenario has indeed played out, with the trough axis remaining too broad and disorganized to tap the impressive tropical moisture feed off of the East Coast. Regardless, an impressive upper level jet streak over the Northeast in excess of 170 mph will aid in the development of more mid level moisture later tonight that should be able to moisten the atmosphere enough so that we see some light to moderate rain along portions of MD/DE/NJ/CT/LI.

Temperatures will likely remain too mild for any pure snow to fall before midnight, however a very light mix of rain/snow may be possible over the farther NW locations of New Jersey and Connecticut. As we move past midnight and into the overnight hours, colder temperatures in the mid to lower levels of the atmosphere will begin to filter into the region, and this is when the best potential for some light snow will exist for the area. However, the vast majority of the precipitation will be centered well-offshore and thus precip rates will be very light. Given the light precip rates, mild temperatures, and meager overall moisture, no significant accumulations are expected for the immediate New York Metro area. Some locations over eastern Long Island and portions of New England will have a better shot at some light snow, but trends with this system will have to be monitored overnight.

This evenings latest RTMA 2m temperatures, surface observations, and regional radar mosaic. Note that despite all of the rain showing up, only stations south of the Mason-Dixon line are actually reporting any rain. This is due to dry air in the mid levels of the atmosphere.

This evenings latest RTMA 2m temperatures, surface observations, and regional radar mosaic. Note that despite all of the rain showing up, only stations south of the Mason-Dixon line are actually reporting any rain. This is due to dry air in the mid levels of the atmosphere.

Tuesday Through Thursday

Tomorrow looks to be an interesting day across portions of the Northeast as the mid to upper level trough associated with this weak coastal system begins to swing eastward and over the region. Some remaining light snow will likely be over portions of Long Island and eastern New England by the morning commute tomorrow, but a more interesting situation will be taking place over PA. As the bulk of the upper level energy moves over upstate NY and PA, lower to mid level forcing will become very strong and we should see at least one band of intense snow squalls develop over central PA. This band will be aided by very steep mid level lapse rates (change of temperature with height) which should allow any squalls to be quite heavy in nature around 8-10 am. As this band head eastward over Pennsylvania, some locations may see brief whiteout conditions with gusty winds and very heavy snow rates capable of dropping a quick 1-3″ locally. As we head into the early afternoon hours, this area of convective snows should be located over far eastern PA and perhaps over portions of Western NJ. This will all depend on how long the mid level energy is able to support this area of snow, but the general brief burst of heavy snow will be possible. Things look to calm down later in the afternoon as the temperature differential begins to even out, so expect any remaining snows to gradually dissipate just to the east or over the NYC metro area. Please use caution if driving through these heavy bands tomorrow, as visibility could drop to around-zero within a few minutes or so!

Evolution of the weak coastal storm as well as the convective snows tomorrow on the latest RPM model (courtesy of WSI)

Evolution of the weak coastal storm as well as the convective snows tomorrow on the latest RPM model (courtesy of WSI)

Wednesday looks to be a generally dry day across much of the Northeast as a weak area of high pressure looks to setup over the Mid Atlantic states. Wednesday looks to be much colder than the past few days as a brief shot of Canadian air makes its way into the Northeast. There may be some high clouds during the afternoon, but high temperatures look to get into the lower to middle 30’s. Later in the evening a weak area of energy will be moving well to the north of the area, with a chance at some snow showers possible for upstate New York and portions of New England. This weak system will help to bring in some warmer air aloft along a frontal boundary, but lows look to stay in the lower to middle 20’s due to radiational cooling.

Thursday is going to likely be a decent warmup from the previous day as stout southwesterly flow works in during the morning hours. This will work to greatly increase the amount of mid level moisture available, which should create a rather cloudy day overall. Some weak mid level energy associated with the Polar jet will also work into the Northeast during the day, which should work to enhance cloudiness and potentially a rain shower or two ahead of a frontal boundary that will be located over the Ohio Valley by Thursday afternoon. This frontal boundary will be the main focus for Thursday night into Friday, as the temperature differential along the front will support at least some moderate precipitation to breakout as it heads east and into the Northeast by Thursday evening. This afternoons model guidance is not in good agreement with regards to just how strong/how much precip this frontal boundary will have, but any light precipitation should begin to work its way into portions of Pennsylvania by late Thursday early Friday.

This afternoons European model showing light to moderate mix precipitation breaking out over portions of the Mid Atlantic and Northeast on Thursday night.

This afternoons European model showing light to moderate mix precipitation breaking out over portions of the Mid Atlantic and Northeast on Thursday night.

Some Snow Possible Into Friday Morning 

The threat for light snow will continue into the morning commute on Friday as the frontal boundary will likely be located right over the I-95 corridor. A strong upper level jet streak will be accompanying this system, so it would not be all that unlikely to see the models become more bullish with the amount of precipitation that develops over the area Thursday and Friday. At this time, this does not appear to be an all-snow event, but rather a mix of rain and snow to start, with light to moderate snow until the front clears. Accumulations looks generally light at this time, but this could change in either direction over the next couple of days, so make sure to check back for further updates!

Much colder and drier air looks to blast into the Northeast Friday afternoon and evening as the front begins to move offshore. Strong zonal flow looks to dominate the country for the majority of the weekend, but we may have to keep an eye on yet another progressive system moving across the country late Sunday and into Monday for the potential for some additional light snow.

This afternoons European Ensembles showing a rather cool, but progressive pattern taking shape over North America with a strong tropospheric vortex centered over Canada.

This afternoons European Ensembles showing a rather cool, but progressive pattern taking shape over North America with a strong tropospheric vortex centered over Canada.

Have a great evening!

Steve Copertino 

Steven Copertino

Brief Warm-up This Weekend, Colder and Potential for Some Snow Early Next Week

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Good evening! 

Today has been another cold, but seasonable day across the entire Northeast as an area of high pressure continues to push off the Mid Atlantic coast this afternoon. Mid level heights have been rising over much of the East coast ahead of a large, but a disorganized mass of energy moving through the central Plains over the past 24 hours or so. These mid level height rises have allowed warm mid level temperatures to move in from the south and over much of the Mid Atlantic region and Northeast, which is the beginning of a more above-normal airmass arriving. With relatively clear skies, stout southerly mid level flow, and light surface winds, we were able to see much of the Northeast rise up into the middle to upper 30’s, with locations off to the south seeing highs get back into the 40’s. Generally clear and calm conditions will exist into for the rest of the evenings and into the overnight hours as dry air exists throughout the low to mid levels of the atmosphere. We should see low temperatures drop a good deal this evening as high pressure remains in control for the most part. Winds will be light from the south, and when coupled with cool and dry mid levels of the atmosphere, we should see readings range from the lower to upper 20’s across much of the NYC area, with lower to middle 30’s possible over southern New Jersey.

This afternoons latest high resolution visible imagery, regional radar mosaic, and surface observations showing a cold, but seasonable day across much of the Northeast

This afternoons latest high resolution visible imagery, regional radar mosaic, and surface observations showing a cold, but seasonable day across much of the Northeast

This Weekend 

Saturday will likely start off as another cold and clear morning as the area of high pressure off the Mid Atlantic coast hangs on for control of the weather for our area. Stout mid level flow from the southwest will continue to pour in from the southern Plains, which will finally cause surface temperatures to respond in a big way. The combination of clear skies, southerly winds and stronger mid level flow should cause highs to get into the middle to upper 40’s across much of the region, with some locations likely breaking into the lower 50’s during the afternoon hours. This will be quite a bit above normal for this time of year and should make for an excellent day to spend outside.  Calm and warm conditions will last through the late afternoon hours and into the evening as the mid level ridging begins to wane to our east. As the mid level ridging backs away, a cold front will begin to make its way into the Northeast by 8-10pm. Cloud cover should rapidly begin to increase as moisture streams in from the south and begins to saturate the lower levels of the atmosphere. Showers should gradually overspread the Northeast overnight, with more steadier rain working its way from west to east by around 2-4 am. Though this front will have Gulf moisture linked to it, the moisture content will not be all that deep, so precip rates and amounts should generally remain in the light to moderate range. We could also see some gusty winds ahead of the front, with winds clocking in around 20-35 mph at times.

Light to moderate rain should last into the early morning hours of Sunday as the cold front continues to move rapidly from west to east. By the afternoon hours the front is expected to be located offshore and we should begin to see dry air from the west begin to fill in behind the front. This should lead to gradually clearing skies and a more westerly/northwesterly winds for the remainder of the day. As skies clear, we should still see temperatures be capable of rising into the lower to middle 40’s with some locations seeing highs in the upper 40’s once again due to warmer low level air lingering around. Sunday night should be rather pleasant as continued clearing and winds from the northwest will remain prevalent over the Northeast.

This afternoons high resolution NAM model showing the progression of the cold front progged to move across the Northeast from Saturday night and into Sunday

This afternoons high resolution NAM model showing the progression of the cold front progged to move across the Northeast from Saturday night and into Sunday

Watching the Coast on Monday and Tuesday 

Things turn interesting starting Monday morning as mid level energy begins to dive into the southern Plains and Ozarks as an area of ridging begins to amplify over the West coast. As this area of energy continues to dig to the south and east, a healthy upper level jet streak will begin to develop overhead. This will promote the development of precipitation off of the southeast coast, which will in turn help to form a weak area of low pressure moving to the northeast by late Monday afternoon. What happens from this point is highly uncertain at this time, but there do appear to be two scenarios that stick out at this time. The first scenario is that the energy in the Tennessee Valley is not far enough south and compact to support the weak area of low pressure strengthening close to the Mid Atlantic coast. In this scenario, the upper level jet streak would be the main driving feature for any precipitation, which would likely be confined to the immediate coast and should be light in nature by Monday night and into Tuesday morning. The next scenario is that the area of energy is stronger and more amplified that what the current computer models are showing, therefore allowing the development of a stronger low pressure system close to the Mid Atlantic coast. As the storm strengthens, the already favorable upper level jet streak would enhance precipitation over the Northeast and some locations could be looking at a light to moderate snowstorm from Monday evening and into Tuesday afternoon.

As of this afternoon, the models are not in agreement with one another, with a wide variety of scenarios being shown. Given the lack of upstream blocking to slow down the mid level energy and allow the low to strengthen, this would usually be a pretty cut and dry forecast, however we have seen a very distinct trend this Winter where snowstorms like to trend more amplified and closer to the coast inside of two days. As of right now we are leaning on the side of caution and using a blend of some of the models that have been performing particularly well this winter. Henceforth, there is a possibility of accumulating snow along coastal and interior locations late Monday evening and into Tuesday. Amounts should generally be light, with coastal locations likely seeing a period of mixing due to the weaker nature of the low pressure system.

However, we must say that there could be some significant model shifts in the next 48 hours that could potentially bring more moderate snow into play, and therefor we will be closely monitoring this system so make sure to check back for updates!

This afternoons European Ensembles showing a low-medium potential for a moderate impact from the potential Nor'Easter on Monday night

This afternoons European Ensembles showing a low-medium potential for a moderate impact from the potential coastal low on Monday night

Have a great weekend!

Steve Copertino 

 

Steven Copertino

Warmer and Dry Through the Weekend, Heavy Rain Possible Early Next Week

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Good evening! 

Today was another cold and dry January day across most of the Northeast as we remain in a rather uneventful pattern for the next couple of days. The jet stream is currently locked in a fast-moving west to east flow across the entire nation. This quick flow does not allow for any disturbances to strengthen and become large storms as the mid level energy that fuels them tends to become sheared out. Despite the quick zonal flow, some cooler air in the mid levels has still been able to bleed down from the southern regions of Canada and into the Northeast. Combined with very dry conditions in the mid levels of the atmosphere, this lead to a seasonably cold and partly sunny day. Highs ranged from the lower to middle 30’s for locations in and around the immediate NYC area, with readings in the lower to upper 40’s across portions of southern New Jersey. This large gradient has been due to more warm air rising up from the south due to increasing mid level heights to our west. Heights will continue to rise through the evening and overnight hours, which will cause surface winds to take on a more southwesterly component. This should in turn usher in more mild air for the Mid Atlantic region and Northeast, with highs likely a good 10-15 degrees warmer than last night. This will equate to lows only getting down into the lower to middle 30’s from the city on south, with locations to the north and west likely seeing temperatures in the middle 20’s.

This afternoons high resolution visible satellite imagery, regional surface observations, regional radar mosaic, showing a rather calm and cold day across the Northeast. Note the ice jam located juts to the south of the "MDT" in southeast PA

This afternoons high resolution visible satellite imagery, regional surface observations, regional radar mosaic, showing a rather calm and cold day across the Northeast. Note the ice jam located juts to the south of the “MDT” in southeast PA

Tranquil Through the Weekend

Saturday will likely start off rather clear and cool as mid level ridging continues to build over the Ohio Valley. Westerly flow will be quite stout in all levels of the atmosphere, with mid level temperatures warming up quite a bit during the day. The combination of warming mid levels and relatively clear skies should allow for temperatures to rise in the upper 40’s to lower 50’s during the afternoon hours. This will be well-above normal for this time of year and it should be a pretty great day to get some chores done around the house. Clear and clam conditions are expected into the evenings and overnight hours with lows likely staying in the lower to middle 30’s for the majority of the NYC area,

Sunday may start off with a few more mid level clouds than Saturday as a large storm system begins to take shape in the Plains. This developing low pressure will greatly enhance the amount of southerly flow over the region on Sunday, which should also work to bring in some more moisture to work with in the lower to mid levels of the atmosphere. This means that despite the increasing mid level temperatures, cloud cover will likely cap off the temperatures right around where they were on Saturday, with middle 40’s to lower 50’s expected. A very weak cold front may try to approach the Northeast late in the evening on Sunday, but this front will likely lack significant moisture to produce anything outside of some scattered showers.

This afternoons NAM model showing increasing mid level temperatures ahead of a large storm system developing in the Plains

This afternoons NAM model showing increasing mid level temperatures ahead of a large storm system developing in the Plains

Heavy Rain Possible Early Next Week

The same large Pacific trough that we have been talking about for the better part of the last week 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 deep tropical moisture feeding into it from the Gulf of Mexico and as a result, a very expansive area of precipitation will likely fan out with the help of an impressive upper level jet streak. Heavy snow and blizzard conditions 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 as it occludes, 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 deep within the warm sector of this system, with temperatures likely reaching into the well-above normal category once again. The models really have not changed much at all over the last 48 hours, with the consensus showing a line of heavy showers and possibly embedded thunderstorms moving through the Northeast on Tuesday morning. Widespread flooding does not seem to be a concern right now due to the speed of the associated cold front. However, this rain will likely be impacting the morning commute in one way or another, so make sure to check back over the next few days as we continue to monitor this large and impactful system!

This afternoons European Ensembles showing a rather high probability for heavy rain to occur during the Tuesday morning commute over a large section of the Northeast

This afternoons European Ensembles showing a rather high probability for heavy rain to occur during the Tuesday morning commute over a large section of the Northeast

Have a great weekend! 

Steven Copertino 

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