We got a taste of what high temperatures should be like for this time of year Wednesday and Thursday, but the cold front that has since moved through will set the stage for a return to below normal temperatures to start the weekend. With a low pressure center well to our east possibly spawning an inverted trough, there is some possibility for light rain/snow mix overnight Friday and into Saturday. Temperatures rebound Sunday and we go into next week with about normal temperatures right around 50.
Rest of today – a noticeably colder night on tap with northwesterly winds in the wake of that aforementioned cold front allowing for low temperatures to dip to about freezing. Any lingering precipitation would manifest itself as rain/snow mix, with points further east having a higher chance of seeing wet snow.
Saturday – a much colder than average day, with high temperatures only hitting the mid-upper 30s, nearly 15 degrees below normal. Cloudy, windy, and raw, with snow showers possible early (accumulation unlikely), and rain showers later.
We are right on the western fringe of a precipitation associated with that low pressure center off of southern Nova Scotia.
Sunday – things clear up nicely as that low pressure keeps pulling off to the east. Temperatures rebound a bit into the low 40s, which is still well below average.
Monday – a continued warmup ahead of a dry cold front, with high temperatures topping out around 50 under increasingly cloudy skies.
Tuesday – a pleasant, seasonable day with high temperatures in the low 50s and mostly sunny skies as high pressure comes into control.
The next chance at precipitation comes Tuesday night into Wednesday with a fast moving clipper system.
Warmer air swinging around a high pressure area to our south.
This upcoming week will feature some big swings in temperature, with high temperatures increasing steadily up through Thursday, when highs could 60 before a cold front swings through. Following the passage of this cold front, we dip back into the mid-40s and continue cooling into the lower-40s this weekend. The temperature trend in the medium term remains below normal, potentially well below normal even through the first week of April, as a series of cold fronts continue to allow cold Canadian air to enter the area.
Monday – an area of high pressure will yield a sparkling sunny day, but will also permit cold, Arctic air back into the region. Northwest winds combined with noticeably cold overnight lows will produce uncomfortably cold conditions. High temperatures Monday may barely break freezing. It’ll be one of the coldest day we’ve had this month.
Tuesday – also gets off to a chilly start, but high temperatures are expected to push up to around 40 (which is more than 10ºF colder than normal).
Wednesday – a clear start, but clouds will be building ahead of a warm front that will pass over the region late Wednesday. Temperatures will steadily climb to near 50, especially after the warm front passes. There will be a slight chance for rain later Wednesday in conjunction with this frontal passage.
Thursday – highs will near if not break 60, however, it is anticipated to be a overcast day with periods of rain possible throughout the day. After the warm front passes Wednesday, we’ll be firmly within the warm sector, between the warm front to our east and the approaching cold front from the west. This setup favors the influx of warm, moist air from the Gulf riding in on persistent southwesterly winds, before a dramatic shift following the cold front passing, with winds becoming west-northwest and a drop in temperatures.
Friday – high temperatures drop back in to the mid-40s, as clouds break apart and colder, dry air takes hold behind the cold front.
Below Normal Start to April
It’s close to a sure bet (70% probability) that we’ll end the month of March and start April with below normal temperatures, taking a look at the Climate Prediction Centers forecasts below. I know we’re all sick of this seemingly endless winter, but we’re still not out of the woods in terms of temperatures.
6-10 temperature outlook from the Climate Prediction Center8-14 temperature outlook from the Climate Prediction Center
The weekend gets off to a wet start, with rain beginning overnight and Saturday a complete washout. By Sunday, conditions will improve and there will be a slight warmup to start the week, before we return to below normal temperatures by mid-week next week.
Rest of Today – increasing clouds will be a precursor for rain later in the overnight hours. If you plan on being out past midnight (really more like 2AM), grab an umbrella just in case. The bulk of the rain doesn’t look to begin until after 2AM, however, once it starts, it will be essentially continuous until Saturday evening. Prior to the passage of a warm front late overnight into Saturday morning, overnight lows may be cold enough to support some mixing of sleet for a brief period in the city. There is actually a freezing rain advisory for northern areas, where a colder thermal profile could support some freezing rain.
Simulated radar image for 3AM EST, Saturday, Mar 14, 2015. High Resolution Rapid Refresh model.
Saturday – it will actually be a mild day on Saturday subsequent to the passage of the warm front mentioned above. Any freezing rain/sleet that occurs early in the morning will quickly transition to rain, increasing in intensity during the morning. High temperatures near 50, combined with drenching rain, should be enough to finally washout any remaining snowpack near the city (although places like Long Island that got more snow this season will probably see it persist).
Sunday – there could be a couple remaining sprinkles Sunday morning, but overall, this should be a dry day, partly sunny, and breezy day. High temperatures will be near normal around the mid-40s.
Monday – it’ll be a nice day Monday with a warm front passing through, and high temperatures in the normal range near 50.
Tuesday – another day of normal temperatures near 50. A cold front pass through by Wednesday, which will lead to a cooler than normal day.
We’ve finally had a stretch of warmer than average weather after what seemed like an endless winter. Things are set to get even warmer tomorrow in the wake of tonight’s rain storm, before cooling off back into normal range to end the week. Another round of rain (with some mixed precipitation inland) will be impacting the area Friday into Saturday.
Rest of today – light rain falling now should increase in intensity over the course of the evening. Steady rain is expected overnight. Dense fog and low visibilities may be a problem overnight into the early morning hours, due to the influence of a saturated, warm airmass approaching an area of colder air. Overnight lows in the low 40s, with dew points around the same (fog often forms when dew point = air temperature).
Wednesday – any remaining rain should end quickly tomorrow morning. Clouds will give way to sun as high pressure begins to take hold over the area. Before too cold air gets into the area due to a northwest wind, we should see temperatures reach the mid-50s (wouldn’t be surprised if some spots hit close to 60 with the increasing daylight hours).
Thursday – another pleasant, and seasonable day, with plenty of sun and high temperatures around normal in the mid-upper 40s.
High pressure in control
Friday – one more day of decent weather, but with slightly more clouds than Thursday. Temperatures should top out around the mid-40s again. The next storm system approaches from the west and rain should begin to fall during the late evening hours. Overnight, some mixing with snow/wintry mix could occur, however, by daybreak Saturday, temperatures will be well above freezing and any mixing should return to all rain.
Saturday – a rainy day, but on the mild side with temperatures near 50.
Next storm coming Friday into Saturday
A cooldown coming
Unfortunately, after a week of normal temperatures, we are likely to see a return to below normal temperatures for the second half of March, based on the following forecasts from the Climate Prediction Center. High pressure will be dropping down from Canada again next week, leading to this greater than 60% probability of below normal temperatures. Luckily, since normal temperatures are now in the upper 40s, the below normal temperatures will not mean a return to the frigid tundra.
Climate Prediction Center 8-14 day temperature outlookClimate Prediction Center 1 month temperature outlook for March
March will start off with quite an active, messy week for us. During the middle of the week, we’ll see snow, rain, and then more snow, before we end off the week with temperatures well below normal once again.
Tuesday – clouds will begin to increase throughout the day with chances for snowfall increasingly steadily as well. Not much in the way of accumulating snow is expected during the day Tuesday. High temperatures around 30.
Wednesday – overnight Tuesday into Wednesday, temperatures will actually rise as a warm front pushes through. This will allow temperatures on Wednesday to top 40. Snow early on will give way to sleet, then eventually transition to all rain. This period of rain should melt some of the existing snowpack, and there could be some minor/nuisance flooding of poor drainage areas as this occurs.
Thursday – once the cold front depicted above pushes through late Wednesday, cold air will rapidly fill in behind it and allow for temperatures to drop back into the mid-20s. As this occurs, a second wave of low pressure is expected to form over the Mid-Atlantic and move over the area. This may lead to enough precipitation to warrant a Winter Storm Warning, with 6″ of snow possible by Thursday afternoon. Highs will be near 30.
Friday – as these storms finally move away, Friday will be a sunny day, but with Arctic air back in place over the area, we’ll be once again welcoming high temperatures in the mid-20s, which at this point is over 15 degrees below normal.
After that brief “warmup” during the weekend, we’re once again mired in Arctic cold air. This cold trend continues with a reinforcing shot of cold air as a cold front sweeps through Wednesday. Behind that, high pressure builds in over the area for the end of the week and into the weekend, ensuring another prolonged stretch of chilly, much below normal temperatures.
Wednesday – ahead of what will a dry cold front passing through, high temperatures may be able to climb to just about the freezing mark under mostly sunny skies.
Thursday – once the cold front moves offshore, an area of low pressure will strengthen, but remain well offshore of the area. However, precipitation may still make its way over the region, especially the far eastern areas. There’ll be a chance for snow flurries further west in the city. Temperatures will be back in the mid-20s again in the wake of that cold front.
Friday – clearing skies will be accompanied by stagnant cold temperatures with highs again in the mid-20s.
Saturday – as you’ll se below, a strong 1040mb area of high pressure will be parked over the Ohio Valley will be responsible for the sunny, but cold temperatures through at least Saturday night. Highs Saturday may approach 30ºF. Normal highs for this time of the year are closer to 40ºF.Looking Ahead
Climate Prediction Center’s 8-14 day temperature outlook for March 4th to March 10th, with our region in an area expected to experience below normal temperatures.
The beginning of next week looks to feature a fairly active pattern, with two storm systems passing through, one on Monday, and another on Wednesday. With the current track of the second storm, it looks like we are going to be on the south side of the low pressure center. This would allow for warmer air to wrap into the area. We could top 40ºF again, but the tradeoff will be a slushy, wet day maybe with some mixed precipitation to start. Once this second storm passes through, we return to cold temperatures once again.
We got a bit of a (cold) respite during the weekend from any precipitation, but all that is about to change in a big way tonight and into tomorrow. A complex storm system that is set to bring snow across a wide swath of the Midwest will be approaching the area tonight and into tomorrow. Various factors make this storm even harder to forecast than the Nor’easter last week, including a still uncertain storm track and a very tight temperature gradient leading to the potential for a mixed bag of all precipitation types in the NYC region.
Impacts
This storm is set to make Monday a downright nasty day to be out. Snow is forecast to begin falling tonight, with areas to the north of the city expected to pick up the most snow through this storm. During the AM rush, temperatures are expected to rise just enough in the lower atmosphere to allow for the possibility of sleet, ice pellets, and a period of freezing rain along the coast near the city, with rain possible further east in Long Island. Then, to close out the day, temperatures will drop rapidly below freezing, such that any slush or melted snow or wet surfaces could flash freeze. Because the temperature gradient is so tightly packed, it will again literally be a matter of miles between a spot that picks up mostly snow and perhaps 8″+, and another location that picks up almost no snow, but gets a significant coating of ice.
Ice accumulation forecast – anything over 0.10″ can cause serious problems.Snowfall total forecast – note the similarity with the last storm as to how dramatically snow totals range across a very small geographic area.
Below are some probabilistic forecast graphics that will give you a good sense of the degree of uncertainty within this storm forecast. First, with respect to snowfall totals over the next 48 hours.
Probabilities of greater than 2″ of snowProbabilities of snow accumulation greater than 4″Probabilities of greater than 8″ of snow
Here’s the same time window, but with probabilities for ice accumulation.
Probability of ice accumulation greater than .10″Probability of greater than .25″ of ice accumulation
In the snowfall probability maps, you can see just how tightly packed the different bands of probability for snowfall are. A matter of 50 miles means the difference between being in an area of 40%-50% probability of receiving more than 4″ of snow, and an area with a greater than 80% chance of receiving the same total.
Timing
Snow will begin to fall later this evening and pick up in intensity overnight. Depending on the area you’re living in, you could see between 3″-8″ overnight, with the highest totals most likely north of the city, and the lowest totals along the coast and in eastern Long Island. Around the morning rush, areas along the coast and eastern Long Island should begin to see a transition from snow to freezing rain, or some type of wintry mix of ice pellets and sleet. Some parts along the coast may even see a changeover from rain/snow to plain rain. In the afternoon, temperatures will drop quickly below freezing, allowing for flash freezing of slush and other wet surfaces. Winds will begin from the east initially before turning northeast and then north through the day.
Why the Uncertainty?
The reason behind the complexity of this storm with respect to precipitation types, uncertainty of total snowfall amounts, rests with storm’s track and the dynamics in the lower atmosphere accompanying this storm. This storm, unlike a Nor’easter, has its genesis over the Central Plains. However, as it approaches the coast, it will still be able to pick up a good amount of moisture off the ocean and from points south.
Recalling that air around a low pressure center in the northern hemisphere in a flows in a counterclockwise motion, you can better understand what is going on here. The low pressure center is forecast to pass just to our south. To the north of the storm center, colder air will dominate, since the cyclonic flow would be pulling air from north to south. Meanwhile, on the south side of the storm center, warmer air is being wrapped into the storm from the south and east. This onshore flow bringing relatively warmer air in close proximity to colder (sub-freezing) air is the reason why there is such a dramatic range in forecast snowfall totals across the area, and also the reason why there is a possibility for a range of different precipitation types.
Above is a forecast map that shows the forecast position and track of the storm. The colored points represent the individual forecast ensemble members (different forecast models with slightly different inputs) predictions for the storm. Notice that there is still a nontrivial spread between these ensemble members. You may also observe that they seem to cluster to the north of the official forecast track (the black line). Indeed, forecasters have been making slight northward adjustments in response to this trend. Should this bear out, and the low pressure center does move a bit further north, we would end up with less snow, more chance for mixed precipitation and even rain. On the opposite end, if the storm track deviates south, we would get more snow, and less chance for mixed precipitation. A very tricky forecast indeed!
On the heels of the nor’easter earlier this week, we get another chance at snow tomorrow night into Friday, albeit of a much lighter intensity. Things get downright frigid after that with low temperatures Friday night in the single digits in the city, and wind chills below zero! The cold locks in over the weekend before we get another chance at precipitation to start off next week, continuing what has been an active weather pattern.
Thursday – clouds increase from west to east, with high temperatures hovering just above freezing. Precipitation begins overnight, and may include some rain/snow mix at the coast (all snow inland), but with minimal accumulations.
We get clipped by a clipper system Thursday night into Friday, with both NAM and GFS models pointing to us being on the periphery of the heavier precipitation.
Friday – light flurries continue into the morning Friday before ending, skies clear quickly while temperatures begin nosediving from a high in the mid-30s during the morning hours to the upper teens by sunset. Winds also pick up from the north and northwest as the departing clipper system from above deepens and the pressure gradient increases between it and a high pressure center over the Midwest. The combination of the cold temperatures and winds will likely induce wind chills below zero, so bundle up before you go out there Friday night.
Saturday – the deep freeze continues, with high temperatures only in the low 20s Saturday despite plenty of sunshine.
Sunday – another day of decent conditions, with clouds increase, but still cold with highs in the upper 20s. Sunday night into Monday, we get another shot at precipitation, although it’s a bit too early to nail down the specifics of this upcoming storm (whether it’ll be rain/snow, rain, or just snow, and how much).
The details are starting to come together for tomorrow’s Nor’easter. Over the past day, forecast models have been pointing to a faster moving system, such that the onset of precipitation is expected to begin overnight tonight, with the bulk of the precipitation ending by early afternoon tomorrow. This storm is expected to throw a little bit of everything our way tomorrow, making for a nasty day overall, with snow changing over to freezing rain or sleet, then perhaps a period of plain rain, followed by a possibility of a rain snow mix.
What to Expect
Snow, moderate to heavy at times, beginning overnight tonight. Winds picking up from southeast, then eventually moving to the northeast and north during the day Saturday. Snow transitioning to a period of possibly freezing rain or sleet during the morning hours, then a period of rain around midday and a possible rain/snow mix towards late afternoon before precipitation gradually tapers off later in the evening. High temperature right around or slightly above freezing.
Forecast Storm Track
Forecast models are in generally good agreement that the center of this Nor’easter will be passing just inside the 40ºN 70ºW benchmark sometime in the late afternoon Saturday (approx 4-5PM).
Without a high pressure center to the north supplying cold air to the area, this setup will allow for enough warm, moist air to circulate around the eastern side of the low pressure center to give us a mix of precipitation throughout the day. The extent to which snow can be sustained will be strongly dependent on dynamical cooling, and how quickly cold air can be pulled in on the western side of the low pressure center.
Storm track forecast from the Weather Prediction Center, with clusters indicating forecast positions of individual ensemble members.
Snowfall Forecast
As you can see below, the probability of more than 4″ of snow is quite low for coastal areas, especially Eastern Long Island, where mainly rain is forecast. The heaviest totals (no more than 5″, most likely) will be concentrated well north and east of NYC where temperatures are expected to be cold enough to sustain all snow for longer. Because the forward speed of the storm is now predicted to be faster, the chances of NYC getting any significant snowfall (even 2″) is considerably lower. Most of the city is in a swath of between 30-40% chance of getting more than 2″ of snow.
Probability of greater than 2″ of snowfallProbability of greater than 4″ of snowfall
Ice Accumulation
The probability of us receiving a trace, but a measurable amount of ice from freezing rain is quite a bit higher than the probability of receiving snow, with most of the city in the 40-60% range.
Probability of ice accumulation greater than .01″
Sunday – the storm will be long gone by Sunday, and we’re expecting to hit highs in the mid-upper 30s.
Monday – there is some potential for a round of all snow on Monday, but forecast models have not been in good consensus on how this will play out. A clipper system is expected to pass through, though it is unclear whether this system will spawn a secondary low offshore. In the latter case, we could see some significant snow, while if it’s just a clipper, we probably won’t see more than a couple inches.
All eyes turn towards the imminent Nor’easter that will be bringing significant winter weather impacts to the NYC metro region. Many variables remain unresolved that could affect the eventual outcome, but at this time, it looks like we’re in for a nasty combination of freezing rain, rain, and snow during the day Saturday. At present, forecasts call for somewhere between 2-4″ of snow in the city along with some ice accumulation. Precipitation should fall as all snow north and west of NYC, however, overall accumulation should be slightly less than in the city itself since the most intense precipitation will remain near coastal areas.
Friday – we get a pleasant, sunny, and slightly above average day with high temperatures in the mid-upper 30s.
Saturday – a tricky forecast for Saturday. What we know for sure, with different forecast models in relatively close agreement, is that an area of low pressure now forming over the Texas Gulf Coast will track over the Southeast, and then offshore of North Carolina by Friday night/early Saturday. Once the low moves offshore, it will rapidly intensify, and then track right on or very close to the 40ºN 70ºW benchmark by Saturday afternoon/early evening.
The uncertain part about this scenario has to do with the thermal profiles in place. With no high pressure over us or to the north pumping in cold Canadian air, the depth of cold (sub-freezing) air will be relatively shallow.
As the Nor’easter approaches us, the cyclonic flow around its center will wrap in some relatively warmer air in from the ocean and points south. This makes for a complicated picture – with warmer air aloft (see animation below) during parts of the day, and below freezing air nearer to the surface throughout points in the day, the recipe is set for at least some periods of freezing rain – precipitation that falls as rain, and then freezes on contact with a sub-freezing surface.
During the middle portion of the day, temperatures should be warm enough at the surface to support plain rain for some time, before transitioning back into freezing rain, rain/snow mix, perhaps with a period of all snow before tapering off Saturday evening.
NAM output of temperature profiles at about 4,800 feet between 10AM and 7PM Saturday. Notice the light pink indicating temperatures between 0ºC and 10ºC, which only gives way to below freezing temperatures (light blue, indicating 0ºC to -10ºC) later in the time frame. The center of the Nor’easter is located within the middle of the set of concentric rings you see near NYC.
Deviations in the storm track to the east would result in more cold air being pulled in from the action of northerly winds on the western side of the low pressure center’s cyclonic flow (less freezing rain/rain, more snow), while deviations of the track west would result in warmer air being in place (less snow, more rain). So, even a slight adjustment in the storm track could alter the thermal profiles, and subsequently what kind of precipitation we see.
Sunday – temperatures overnight Saturday will be below freezing, which would allow anything that fell and melted to refreeze. Things do clear up Sunday, with highs about average in the mid-30s, and with clouds diminishing.
Monday – there is a chance for yet another round of mainly snow, potentially heavy, as another coastal storm is possible. Highs will be close to the freezing mark, making this an all snow event if it should pan out.
