February 2018 – Page 5 – New York Metro Weather

Wintry Mix Exits, Unsettled Pattern Sticks Around Through Next Week

February 7, 2018/1 Comment/by Steven Copertino

Good Evening!

The area of low pressure that moved inland over much of the Northeast is finally beginning to wind down, with precipitation shutting down from west to east. The storm initially came up from the southwest early this morning, producing a wide area of snow and mixed precipitation over much of the Mid Atlantic and Northeast. The areas that did start off as snow around the New York metro area this morning gradually saw the snow change to sleet, and then light to moderate patches of freezing rain as warmer air in the mid levels began to push north. As mentioned on Monday, there was a chance that the low level cold would be under-modeled as it has many times in the past, and that is exactly what happened this morning/afternoon. Despite mid level temperatures above freezing a few thousand feet above the ground, surface temperatures remained at or below freezing just long enough to allow for quite a bit of freezing rain to fall across southern portions of New England as well as portions of the Mid Atlantic states. This freezing rain caused very hazardous travel conditions for the morning commute, with many folks getting caught off-guard by the unexpected slick conditions. As the area of low pressure continued to move to the north and east this afternoon, warm air began to surge in at all levels, and this caused most, in not all of the precipitation in the area to turn to plain rain. Some locations in southern New England are still dealing with light to moderate freezing rain, while locations well to the north are dealing with moderate to heavy snow.

Continued moderate rain will be likely over portions of the Mid Atlantic and southern portions of the Northeast through at least 8pm, with precip gradually ending from west to east. Colder air will be working its way east as well behind a frontal system, so there will be a slight chance that the precip could end as light snow or a light mix. Temperatures will once again drop below freezing this evening, with much of the area seeing lows drop back into the middle 20’s, with locations off to the north and west likely flirting with teens due to the snow cover. Regardless, conditions will remain hazardous for travel during the evening commute, so please use caution while driving on untreated roads!

This evenings latest high resolution visible satellite imagery, regional radar mosaic, and surface temperatures over the Northeast showing a wide variety of weather conditions

Thursday Into Friday

Conditions will start off rather cold on Thursday morning as an area of high pressure builds off to our west over the Ohio Valley. Temperatures will have likely dropped quite a few degrees below freezing during the overnight hours, so expect any puddles or standing water to have frozen over, making for another potentially slippery commute. Black ice may be rather prevalent over the area tomorrow morning as well, so please use caution! Regardless, the rest of the day looks rather calm as the area of high pressure over the Ohio Valley continues to build, leaving most of the Northeast rather sunny. Colder and drier air will be working its way down in the mid levels of the atmosphere from Canada, so we expect highs to generally stay in the middle to upper 20’s. Conditions will remain calm and cold through the evening hours as the area of high pressure continues to move over the Mid Atlantic. As it does so, conditions will become rather favorable for radiational cooling to set up over the Northeast, allowing for lows to drop into the middle teens and 20’s across much of the area.

Friday looks to be rather similar to Thursday, just with a chance of more clouds and significantly less windy. The Pacific jet stream will begin to go zonal over the entire country (west to east), which will signal the start of a warmer period, but also an unstable one. This west to east pattern will allow for multiple impulses of energy to quickly move from one coast to the other rather quickly, but a lack of anything to slow them down along the way will keep each disturbance weak and disorganized. One such disturbance looks to be over the northern Plains on Friday afternoon, which could cause some very light rain or snow to break out over northern portions of the New York metro area later in the day before quickly moving to the east. Major changes will be underway by Friday night, as strong low level flow begins to establish itself from the southwest, ushering in warmer mid level temperatures. This will allow for lows on Friday to mainly stay in the middle to upper 20’s, with some locations staying in the 30’s.

This afternoons NAM model showing significant warm air advection over the Northeast on Friday afternoon, leading to a change to warmer temperatures

Unsettled Conditions This Weekend

Starting on Friday, the subtropical jet stream will begin to expand over the Gulf of Mexico, creating abundant latent heat release which will eventually get caught up in the strong southwesterly flow over the eastern US. Our next system will begin to take shape over the southern Plains on Saturday morning as moisture-rich air runs into cooler mid level temperatures, sparking a large area of precipitation. The zonal jet streak will still be present over the northern tier of the country, and this will only work to enhance precipitation growth and intensity over the south. Snow will be possible over portions of the Mid West through the Ohio Valley where the colder air can hang on longer, as high pressure dives into the central Plains states. Mid level ridging over the western Atlantic will only help to enhance the northward transport of moisture into the Northeast on Sunday morning as light to moderate rain begins to break out. Rain looks to last pretty much all day on Sunday, likely making the day a washout. Due to the progressive nature of this system, flooding does not look all that likely in the Northeast, however there still may be some heavy downpours as precipitable water amounts will be quite high for this time of year. Temperatures this weekend will also be quite anomalous, with highs likely getting into the 40’s and lower 50’s across much of the Mid Atlantic and Northeast.

Another wave may develop along a stalled frontal boundary to our west on Monday, leaving us with another threat at some moderate rain to start the work week. At this time, it appears that the threat for substantial snowfall from either system is rather low, but we will continue to monitor these systems as they draw closer!

This afternoons NAM model showing an impressive moisture feed setting up directly from the Gulf of Mexico

Have a great evening!

Steve Copertino

High latitude blocking a key in the late February forecast

February 7, 2018/1 Comment/by John Homenuk

Over the past several days you have probably heard about a Sudden Stratospheric Warming event (SSW) — over, and over, and over again. With good reason, too – the event is important. We spoke about it several days back and will touch on it here again. Forecast models continue to suggest the development of a very impressive stratospheric warming event over the next few days, beginning in just 24-48 hours and continuing through next week. The stratospheric vortex itself will split in two, with the dominant sister vortex centering over Canada.

Warmer than normal temperatures and higher than normal heights will surge into the stratosphere near the North Pole and Arctic regions. Most notably, the stratosphere and troposphere are well coupled heading into the event, which means the warming in the stratosphere will have “maximum impacts” on the atmosphere as a whole – with the troposphere reacting to the warming event happening above rather quickly.

Tuesday Briefing: Interior winter storm on the way

February 6, 2018/by John Homenuk

Good morning and Happy Tuesday! We’re continuing our Daily Briefing series, where we provide free public weather updates for various parts of the country. Thanks for reading! A significant winter storm is expected to develop later today and Wednesday across the Northeast states, particularly in the interior areas, where snowfall amounts upwards of 6″ are possible.

The airmass in place ahead of the storm system is not particularly cold, and without any high latitude blocking there is no mechanism to hold in a cold high pressure to the north. All of this will aid in warm air surging northward as the storm develops, allowing precipitation to quickly change to rain along the coast. Inland, and in the higher elevations, colder air will hang on a bit longer and more impactful snow and wintry precipitation is likely.

Winter Storm Likely Wednesday for Portions of the Northeast

February 5, 2018/by Steven Copertino

Good evening!

Today has been a rather cold and blustery day across the entire Northeast as a cold front quickly blasted across from west to east early this morning. This cold front ushered in a fresh blast of cold air from Canada, causing temperatures to drop a few degrees this morning before peak daytime heating. As the cold front moved offshore, dry air filtered into the region which allowed for mostly sunny conditions to persist throughout the rest of the day. Despite the clear skies, the cold mid level temperatures only allowed for temperatures to rise into the lower to middle 30’s for the immediate NYC metro area. Highs were a bit lower to the north and west with temperatures staying in the middle to upper 20’s-which is only slightly below normal for this time of the year. The main story today was actually the winds that arrived immediately after the frontal passage, which gusted at around 30-35 mph at times. These winds really helped to make conditions feel quite a bit colder than they actually were, with wind chills in the middle to lower teens. Additionally, any residual standing water left over from melting snow quickly froze this morning, leading to some very slippery conditions across the entire Mid Atlantic and Northeast.

Conditions will remain quite clear, with winds gradually abating by around midnight. A weak area of high pressure will work over the Mid Atlantic this evening and provide rather favorable conditions for radiational cooling to take place tonight. Highs should drop down into the middle to lower 20’s for most of the NYC metro area, with locations to the north and west getting down into the middle teens for lows.

This afternoons high resolution satellite imagery and surface observations over the Northeast

Calm Tuesday, Winter Storm Likely Wednesday

Tuesday: A weak area of mid level energy will be racing across the Ohio Valley and into portions of the Northeast tomorrow morning, which will have to be closely monitored for possibly being able to produce some areas of light snow in the morning. This area of energy, being so weak, will not have a reliable source of moisture and will also be running into dry air. This will cause the threat of snow to be greatest over western locations of the Northeast. Any snow that does fall will very light in nature and should only lead to accumulations of around a trace to an inch. This area of energy will likely move off the coast by the middle afternoon hours, gradually giving way to clearing skies from west to east. Despite the threat for some isolated snow, the rest of the day should be mainly calm and cool, with highs staying in the low to middle 30’s across the immediate NYC metro area. These calm and conditions will last through the evening hours, with lows ranging in the middle to upper 20’s.

By Wednesday morning, two areas of energy will begin to interact over the central Plains states, leading to a very weak surface low developing over the Tennessean valley. As this low develops Wednesday morning, it will drag up a moderate amount of moisture with it that will likely cover the majority of the eastern US. The area of high pressure that is currently dominating our weather will be retreating to the east by this time, leaving some residual cold air behind over the Northeast. Precipitation will likely expand further to the north and east during the morning commute on Wednesday as an impressive upper level jet streak strengthens overhead. Since the surface high will be displaced to the east, the cold air will only be able to stick around for so long as warmer air begins to rise up from the south. This will likely lead to a quick-hitting period of moderate to heavy snow propagating from south to north , that will gradually change to rain over time as warmer air moves north. The further north and west you get from New York City, the better chance you have at more wintry precipitation. At this time, points south and east stand to get maybe a coating to an inch before the changeover to rain, but locations over NW New Jersey and SE New York have the best chance to see at least a couple of inches before a mix and eventual change to rain sets in.

It is important to note that the hi-res models have been waffling quite a bit over the past day or so, and this is mainly due to the handling of the extent of the low level cold air. If the cold air sticks around longer, there will be a greater threat of snow lasting longer in addition to more substantial frozen precipitation accumulations. These types of events usually do tend to be colder than forecast, which is why we feel that those traveling Wednesday morning keep an eye on the weather and stay tuned for further updates, as travel may be at least moderately impacted across the region.

Precipitation will gradually end from southwest to northeast as the low quickly heads off to sea during the evening hours on Wednesday.

This evenings NAM model showing the evolution of the winter storm over the Northeast on Wednesday

Another Storm Possible Next Weekend

The computer models continue to depict another area of low pressure developing over the Tennessee valley Saturday and into Sunday as yet another area of high pressure exits to our east. This system will likely be quite large and disorganized in nature as the upper level pattern remains quite unfavorable for a strong surface cyclone. Additionally, there does not look to be a reliable source of cold air over the east, therefore any chance at significant snowfall through the weekend remains low at this time. There is still a lot of time for this to change over the next couple of days so make sure to check back for updates as they become available!

This afternoons GFS model showing the potential for another system to impact the east this weekend

Have a great night!

Steve Copertino

Archive for month: February, 2018