Posts

Steven Copertino

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

/by

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

/by

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

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

/by

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 

Miguel Pierre

More Volatile Pattern with Significant Storm Threats Into Next Week

/1 Comment/by

Happy Wednesday! High pressure will be off the Northern-Mid-Atlantic coast with more light onshore winds today. Sunshine this morning will be fading behind more high clouds this afternoon, as mid-level warm air advection increases. Temperatures are expected to be a little cooler this afternoon with highs in the upper 30s to lower 40s. These temperatures closer to normal for this of time year.

Mostly cloudy skies are expected for tonight and Thursday, as mid-level warm-air advection increases, ahead of approaching warm front. Temperatures will actually hold steady this evening the slow rise into into the mid-upper 40s by Thursday morning. Highs on Thursday afternoon will be in the upper 40s to lower 50s. On top of the remaining snow pack, moisture levels or dewpoints will be increasing underneath inversion, leading to some areas of patchy fog and drizzle.

Read more