This week starts off quiet, and cold with sunny skies today. Tomorrow brings a mess of rain/snow mix, rain, then possibly ending with snow leading into Wednesday. A blast of Arctic air lies behind the storm system bringing this precipitation, with low temperatures plummeting into the single digits overnight into Thursday. The Arctic chill stay in place until the weekend.
Rest of today – sunny, with some scattered high clouds. Temperatures around freezing. Overnight lows in the upper-20s.
Tuesday – the timing of the next storm system to affect us, at this time, points to a period of rain/snow mix starting in the late morning Tuesday. A warm front should induce enough warm advection to raise temperatures into the low-40s. That will allow for a transition to all rain in the city until the overnight hours when temperatures are forecast to fall below freezing into the upper-20s. A period of all snow should follow.
Wednesday – periods of heavy snow squalls are possible before the storm finally clears out. At this time, forecasters are calling for about 1″ of snow accumulation starting Tuesday night for NYC. If the forecast trends colder, we could see some more snow, but no blockbuster amounts either way. High temperatures Wednesday should rise to around freezing. On the cold back side of the passing storm, Arctic air will swing into the region. Overnight lows are forecast to only be in the single digits going into Thursday morning.
Weather Prediction Center surface forecast for 7PM Wednesday
Thursday – frigid day in store with Arctic high pressure in control. Sunny skies but temperatures only expected to reach into the mid-teens. Overnight lows into Friday will stay chilly, only around 10°F.
A quiet, and mostly dry weekend is on tap after a wet and windy day yesterday. This will be a welcome change of pace from the active weather pattern we’ve seen on prior weekends. There isn’t any precipitation expected and temperatures are forecast to alternate between the low-40s and low-30s. The next chance for meaningful precipitation comes Tuesday.
Rest of today – high temperatures near 40ºF, partly sunny with winds picking up in the afternoon. Overnight lows will be much cooler in the wake of a dry cold front passing through around 20ºF.
Saturday – high pressure will be in control for the day, but it’ll be a cold day with high temperatures topping out in the low-30s under partly sunny skies. Overnight lows warmer in the upper-20s as the high pressure center moves off to the east and winds shift to the south.
Sunday – temperatures warm into the low-40s with return flow from the south on the west side of the departing high. Overnight lows will be similar to Saturday in the upper-20s.
Weather Prediction Center surface forecast for 7AM Sunday
Monday – things turn colder again in the wake of another cold front passing through with high temperatures in the low-30s with partly cloudy skies.
What ended up being a rain storm for NYC yesterday has brought along the coldest air of the year in its wake. The bitter Arctic chill won’t last long, with temperatures on an upwards trend through the mid-week period as another storm approaches. By Thursday, temperatures in the upper-40s will feel like summer compared to the frigid start today. Beyond that, temperatures look to cool off again into next weekend, but it appears to be a dry weekend ahead.
Rest of today (MLK Jr. Day) – overnight lows in the city were in the single digits, and despite lots of sun, the Arctic high in control over the area will limit any significant warming. High temperatures are expected to be in the mid-teens with blustery northwest winds making wind chills feel below zero. Overnight lows dip back into the low-teens, but winds should abate somewhat as the core of the Arctic high moves closer to us and the pressure gradient relaxes.
Tuesday – much warmer than today, by about double, but still cold with high temperatures in the upper-20s. Sunny skies expected with high pressure still in control. Not much change in temperatures overnight into Wednesday as the next storm system brings a warm front to the area.
Weather Prediction Center surface forecast valid 7AM Wednesday
Wednesday – temperatures in the low-40s as we get in the warm sector of an approaching low centered over the Great Lakes. Temperature profiles should support all rain, though there could be some mixing early Wednesday as precipitation starts. Overnight lows again don’t budge much. More rain is expected going into Thursday.
Thursday – long duration rain event continues, with temperatures in the upper-40s and mostly cloudy skies when it’s not raining.
The dusting of snow we got last night into today is just a small preview of what lies ahead this weekend. A major storm, that first brought heavy rain to the west coast, has been tracking across the nation and will impact the region late Saturday through Sunday with potentially a mixed bag of everything from snow, sleet, freezing rain, rain, urban street flooding, coastal flooding, and strong winds that could result in power outages and tree damage (esp. if ice accumulates). Behind this storm, the coldest air of the new year surges in, bringing a bitterly cold start to next week. I’ll post an in-depth forecast of the incoming winter storm tomorrow.
Rest of today – the veritable calm before the storm. High pressure briefly establishes itself behind the weaker disturbance that brought us light snow overnight. Skies slowly becoming partly cloudy. High temperatures in the low-40s. Overnight lows colder around 30°F.
Saturday – should start off as a decent day with partly cloudy skies. Cloud cover increases through the day, and snow starts to spread from southwest to northeast during the late afternoon hours. High temperatures in the mid-30s. Overnight lows right around freezing will critically impact how much snow accumulation we get before what is widely expected to be a transition over to wintry mix of sleet and freezing rain, then finally bouts of heavy rain leading into Sunday. If a warmer scenario plays out, we’ll get less snow and ice, and more rain. Various forecast sources call for between 1-4″ of snow and sleet accumulations, with up to as much as 0.10″ of ice.
Weather Prediction Center surface forecast for 7AM Sunday. A real mixed bag of various precipitation types all along the Mid-Atlantic and Northeast
Sunday – high temperatures will continue to play a pivotal role Sunday in determining precipitation type. Some forecast sources suggest colder high temperatures in the mid-30s, while others remain warmer, in the upper-30s to even 40°F. There is broad agreement that the day starts off with plain rain but then transitions back to wintry mix of sleet, freezing rain, and finally snow. The differences in high temperature will be pivotal to the timing of this transition, with a warmer scenario keeping things all rain longer. As the center of the low responsible for the storm moves off to the north and east, it will continue intensifying and the pressure gradient around it will increase quite dramatically. Robust northwest winds are expected to develop, rapidly advecting cold, Arctic air into the area. The intensity of this cold advection will govern how quickly temperatures start to plummet during the second half of Sunday. It would appear that temperatures will be well below freezing by the late afternoon hours. This prompts concerns for a flash freeze of any standing water or untreated surfaces, leading to dangerous travel conditions. Temperatures will continue dropping overnight Sunday, with overnight lows going into Monday only around 10°F. Overall, this forecast shapes up to be a slushy mess, with a layer of snow coated by ice and sleet, melted by rain, but then re-frozen with an additional light layer of sleet and ice before all is said and done.
Weather Prediction Center’s plot of ensemble forecast low tracks/positions. Note that there’s still decent uncertainty even at this stage approaching the storm. The pink cluster denotes storm center positions by 7AM Sunday. Though they seem closely clustered, even a shift of the storm track 25-50 miles north or south could result in big differences in terms of whether locations at the coast receive more snow and frozen precipitation (southerly track) versus more of a rain event (northerly track).
Monday (MLK Day) – if you have the day off, count yourself lucky, because this is shaping up to be a brutally cold day where temperatures topping out in the upper-teens despite ample sun. Continued windy conditions will produce wind chill values below zero. The bitter cold continues into Tuesday morning with overnight lows again in the low-teens.
We will get a slight warm up going into the mid-week period this week. Precipitation will hold off until late in the week, when two storm systems are forecast to push through. Temperatures could be cold enough to support some snow, though rain should also mix in at some point.
Rest of today – mostly sunny with high temperatures in the mid-30s. Lows overnight will again be quite cold, in the mid-20s with mostly clear skies helping aid radiational cooling.
Tuesday – warmer with temperatures in the upper-30s and mostly sunny skies. Lows going into Wednesday also a touch warmer, in the upper-20s.
Wednesday – temperatures finally forecast to break above 40°F. This is because we’ll be in the warm sector ahead of a cold front attached to an Alberta Clipper type low pressure system. Overnight lows behind this cold front will return to being cold, in the mid-20s.
Weather Prediction Center surface forecast for 7AM Wednesday.
Thursday – a sunny day with high pressure in control briefly behind the cold front above, temperatures in the low-30s though. Overnight going into Friday, a disturbance is forecast to move towards the region and could touch off some snow flurries with temperatures in the upper-20s.
We’ll have a cold weekend ahead, however, we will dodge a bullet with a major winter storm tracking to our south. The northern fringes of this system could still bring some light snow to the city, though. The cold temperatures stay in place through the weekend and into early next week. Looking ahead, we should see a pattern change that leads to some warmer temperatures by mid-week next week
Rest of today – mostly sunny, cold, with high temperatures hovering around 30°F. Gusty northwest winds steadily subsiding as a strong Arctic high pressure center moves closer to us. Clear, crisp night with overnight lows around 20°F.
Saturday – partly sunny, high temperatures topping out around the freezing mark. Snow flurries are possible overnight into Sunday. Overnight lows in the mid-20s.
Weather Prediction Center surface forecast for Saturday at 7AM. Note the strong Arctic high pressure to our north, 1040 mb, which will effectively block the winter storm to the south from heavily impacting this region.
Sunday – partly sunny with clouds possibly breaking from north to south later in the day. Some flurries still possible early in the day. High temperatures similar to Saturday around freezing. Overnight lows in the low-20s.
Monday – mostly sunny, with high pressure building again, temperatures still cold in the mid-30s.
We get a quick passing storm tomorrow that will bring a shot of rain/snow mix. A couple windy days will follow this before our attention turns towards a possible weekend nor’easter. As of now, temperature profiles appear to support the possibility of an accumulating snow event, if the storm track supports precipitation. The picture will become more clear later in the week as more forecast data comes in.
Rest of today – increasing clouds with temperatures in the low-30s. Temperatures will increase overnight as a warm front attached to an incoming low pressure system approaches from the southwest. Moisture will also increase and precipitation could begin falling overnight. Forecast soundings suggest temperature profiles will support a period of snow/sleet when precipitation does fall.
GFS forecast sounding for 1AM Tuesday morning, the atmosphere is beginning to saturate even at low levels. Temperature profiles remain below freezing through most of the atmosphere at this time, so if/when the atmosphere saturates, precipitation would be mostly frozen until the very near surface layer, suggesting sleet. See this post for how to read a Skew-T.
Tuesday – mixed precipitation could linger into the morning hours. Temperatures should continue to warm with southwest flow behind the warm front (warm sector) and ahead of an approaching cold front. High temperatures should reach into the upper-40s. Thing should dry out for a bit, but a second round of rain may accompany the passage of this trailing cold front. This cold frontal passage will be accompanied by strong lift, enough to even support a couple thunderstorms. Overnight lows will remain in the low-40s.
Weather Predicition Center surface forecast for 7PM Tuesday.
Wednesday – temperatures in the mid-40s. Winds will pick up into the 20-25 mph range with stronger gusts in the 30 mph range as the low pressure continuing to strengthen as it moves east. Partly sunny skies for the most part this day. Overnight lows will be much cooler, in the low-30s in the wake of the cold front passage.
GFS surface pressure and wind forecast for Thursday at 7AM. Note the dense packing of isobars (black lines indicating areas of the same pressure) over the northeast. This is due to the strengthening low exiting east over Nova Scotia and high pressure building from the west. The result will be strong winds impacting the area.
Thursday – windy conditions continue with high temperatures significantly cooler in the upper-30s under clearing skies.
The first weekend of 2019 holds a mixed bag for NYC. Saturday looks to be a rainy day, while Sunday should shape up to be a pleasant, milder day, though not nearly as warm as New Year’s Day. Going into next week, another storm system approaches and may bring precipitation as early as Monday evening. This weekend, I’ll have a follow up post regarding the high likelihood of El Nino developing in the Pacific this winter, and what implications this could have for tangible weather this season in our region.
Rest of today – Increasing clouds. High temperatures in the mid-40s. Overnight, rain starts to move in ahead of an approaching warm front associated with a surface low tracking east and offshore of the Delmarva Peninsula. Overnight lows around 40.
Weather Prediction Center surface forecast for 7AM Saturday. With a warm front positioned to our south, persistent northeasterly onshore winds will present a possible issue for coastal flooding, and keep temperatures suppressed.
Saturday – rain for the bulk of the morning and the afternoon hours. Cooler, with onshore flow north of the warm front mentioned above. Temperatures topping out in the low-40s. Rain tapering off towards the late evening hours, then skies steadily clearing with overnight lows in the mid-30s.
Sunday – bright, sunny day on tap behind the storm system Saturday day. Temperatures a touch warmer in the mid-40s. Overnight lows into Monday dropping into the low-30s as a cold front moves through. No precipitation anticipated with this cold front at this time.
GFS model output for Monday at 5PM. By this time, we’re forecast to be under an area of high pressure, but wedged between the departing weekend storm and the next storm approaching form our west.
Monday – increasing clouds ahead of the next storm system. Temperatures in the mid-30s with colder air in place behind the cold front mentioned above. Overnight lows holding steady, dropping a couple degrees maybe – another warm front will help stabilize temperatures as rain or a rain/snow mix develops. Exact precipitation type is difficult to determine at this time.
A wet, windy New Year’s Eve in NYC will give way to a very mild day to start 2019. However, for reasons outlined below, I don’t believe that record warm temperatures will be broken tomorrow. Strong winds will be a distinct possibility, though, and as such the National Weather Service has issued a wind advisory for the area. I think sustained winds could reach 30 mph, especially early in the day.
My Forecast
High: 57°F | Low: 36°F | Max sustained winds: 30 mph | Total precipitation: 0.04″ – verification for temperatures and precipitation will come from METAR data for the period between 1AM Tuesday and 1AM Tuesday (06Z Tuesday to 06Z Wednesday) at LGA. Wind speed verification will draw on the daily climate summary from the National Weather Service.
Verification
High: 60°F | Low: 40°F | Max sustained winds: 36 mph | Total precipitation: 0.02″ – this wasn’t a great forecast, aside from the precipitation. I was once again overly conservative on max wind speeds. Following layer mean wind analysis results would have yielded an almost perfect forecast here. For temperatures, I think the main issue was that the low level clouds I thought would materialize based on the forecast soundings available the day before just never came to be. This allowed high temperatures (and hence low temperatures) to become warmer than I forecast. In this case, perhaps it would have been prudent to consider that winds would be downsloping from the northwest, hence drying out somewhat at lower levels. This wind direction also favors clearing conditions following a cold front passage from the west.
Weather Prediction Center surface forecast for 7AM Tuesday
Synoptic Set Up
NYC will start the day off in the warm sector of a low pressure center tracking northeast through New England. This low will continue to deepen as it progresses east. The tightening pressure gradient will induce strong winds, and a trailing cold front will cross the region bringing about much colder air in its wake. Temperatures will peak early in the day and drop steadily through the day. The low temperature will occur late in the forecast period.
High Temperatures
Steady warm advection overnight with a warm front and warm sector associated with the parent low above will mean that temperatures increase to the mid-50s by day break. Forecast soundings from both GFS and MOS indicate, persistent, low overcast that I believe will be pivotal to keeping temperatures from going above 60°F. These low overcast clouds should block out enough sun to keep things a bit cooler than otherwise would be. Forecast soundings also show some upper level clouds that would help block additional sun. For these reasons, I’m siding with cooler NAM MOS guidance that calls for 55°F, and bumping up a couple degrees. Cold advection should take hold quickly in the afternoon in the wake of the trailing cold front. This will usher in westerly and northwesterly winds, which will downslope and warm a touch but will still overall bring colder air into the area. Once this cold advection takes place, temperatures should start to fall.
GFS forecast sounding for 9AM Tuesday, showing a well mixed layer up to about 825 mb and low clouds around 800 mb.
Low Temperatures
Because of the factors above, the low temperature should end up coming in late in the evening/overnight period going into Wednesday. I believe there’s not too much reason to deviate from MOS guidance which averages out to be about 35°F.
Max Sustained Winds
A well-mixed boundary layer is forecast to develop with pretty strong winds aloft in the late morning hours. A period of efficient downward momentum transfer should allow fast winds from above to mix down to the surface. Layer mean wind analysis suggests that winds could be as strong as 35 mph, however, I’m going a bit lower with sustained winds topping out at 30 mph since neither set of MOS guidance goes over 20 mph.
Total Precipitation
It’s clear at this point that the bulk of precipitation will fall before the beginning of the forecast period. However, both sets of MOS guidance, SREF and GEFS means all suggest some precipitation early in the overnight period. I’m going with a composite average of various sources at 0.04″.
New Year’s Eve this year looks like a washout, but temperatures will be very mild. In fact temperatures will maintain a non-diurnal trend, warming through the night. New Year’s Day could see the possibility of record warmth before a return to more normal conditions mid-week. Another storm system approaches for the end of the week.
Rest of today – cloudy with high temperatures in the upper-40s. A warm front approaching from the south and west will start to bring steady rain to the area by late afternoon. A favorable low-level jet, along with robust isentropic lift (overrunning of warm air above cold air along the warm front) should enable plenty of moisture and enough instability to trigger bouts of heavy rain later in the evening and overnight. Unfortunately, the bulk of rain looks to fall right during periods when revelers will be out on the town celebrating the new year. Winds will pick up as well with the pressure gradient tightening and efficient downward momentum transfer of low-level jet winds during periods of precipitation. As mentioned above, temperatures will follow a non-diurnal trend, with the warm front and warm sector of this storm advecting milder air from the southeast. Temperatures will actually rise into the mid-50s overnight.
NAM (North American Model) forecast of 850 mb relative humidity and winds for 10PM tonight. The blue hues indicate saturated air, while we can see some wind barbs showing winds > 60 knots. These are classic signs of a low-level jet that is often implicated in producing heavy precipitation events.Weather Prediction Center surface forecast for 7AM Tuesday. Note the tight packing of isobars (black lines) around the parent low that’s going to bring us rain. This indicates a tight pressure gradient that will drive strong winds. This surface forecast also suggests that our time in the warm sector of this low (outlined in light orange above) will be brief. Warm advection (transport of warm air) won’t last long into Tuesday.
Tuesday (New Year’s Day) – I’ll follow up with a detailed forecast, the start of 2019 will be quite interesting for a couple reasons, one being possible record warmth and the other being strong, gusty winds. Temperatures will be rising throughout the night into Tuesday such that high temperatures will peak early in the day. Depending on exactly when this happens, temperatures could push above 60ºF, which would be nearing or exceeding records. The record high for January 1st at Central Park is 62ºF set in 1966. A lot will hinge on whether clouds clear up early enough to allow for a few hours of solid sunshine. This warmth will be short-lived though, because we won’t spend that much time in the warm sector of this parent low. As a trailing cold front moves through, winds will shift to the northwest and result in cold advection. As a result, temperatures will be falling during the day into the upper-40s by sunset. Temperatures are forecast to continue dropping overnight into Wednesday with lows bottoming out around freezing in the city.
Wednesday – a rude awakening to normal temperatures for this time of year. There will be a cold start to the day with high temperatures 20ºF cooler than Tuesday, in the upper-30s. Partly cloudy skies. Overnight lows in the mid-30s.
Thursday – warmer than Wednesday with another storm system approaching. So far, looking at a mostly cloudy day with highs in the low-40s. Rain may start as early as the overnight hours. A lot of uncertainty still at this time with the timing, scope, and precipitation type of this next storm though.
