In contrast to last weekend, where Sunday was the better half, the reverse will be true this weekend. Remnants of Tropical Depression Bill will be moving over us on Sunday, bringing the potential for extended periods of showers and heavy rain. It is hoped that this much needed rain will put a dent in the persistent moderate drought conditions in the region.
Rest of today – there is a small chance for thunderstorms up until around lunchtime today, after which skies should gradually clear. High temperatures are expected to top out in the upper-80s to near 90.
Saturday – high pressure will be shifting to the east, bringing in an onshore flow, keeping temperatures cooler in the upper-70s under partly sunny skies. Chances for rain will be increasing steadily through the evening such that by the overnight hours, periods of steady rain should be the norm.
Sunday – As referenced above, remnants of Tropical Depression Bill, still carrying tropical moisture, will be moving over the region. There is still some uncertainty as to whether the areas of heaviest rain will move further south and over the ocean, however, at this point it seems likely that Sunday will feature periods of steady rain, heavy at times. Rainfall probability and rainfall totals will drop precipitously from south to north, since the storm center is expected to track to our south. We could pick up as much as 1″-1.5″ of rain over Long Island, which would be a blessing since this area is still in the grip of moderate drought conditions. With clouds and rain, high temperatures should top out around 80.
Quantitative Precipitation Forecast for SundayNorth American Model high resolution output for Sunday at 11AM EDT Drought coverage in New York as of this week
Monday – conditions improve following the passage of the storm on Sunday, with high temperatures rebounding into the mid-upper 80s under mostly sunny skies.
It certainly does feel as though Memorial Day 2015 has been the unofficial start of summer, given the warm and humid temperatures we’ve had from Sunday onwards. The warm, late-June like temperature trend continues through mid-week, with some chance for thunderstorms. Rain in any form would be most welcome, given that the region has been placed in a region of moderate drought as of this week.
Rest of today – the Bermuda high, more typical of mid-summer, brings us very warm and humid high temperatures in the mid-upper 80s, more than 15ºF above average for this time of year. If you like the heat, go out and enjoy it because we might see showers and thunderstorms both Wednesday and Thursday afternoons.
Wednesday – a weak cold front approaches from the west, bringing with it a chance for showers and thunderstorms. The critical question for NYC will be how long organized storms can stay together as they enter into influence of cooler, maritime air nearer to the coast. Temperatures will remain warm in the low-mid 80s with clouds and some breaks of sun. As is generally the case in these setups, the more sun we can get in the afternoon ahead of the frontal bou
North American Model high resolution simulated radar image for 8PM EST Wednesday
Thursday – we get another shot at thunderstorms Thursday afternoon and evening, with highs likely topping out around 80 under mostly cloudy skies.
Moderate Drought for the Region Forecast to Persist
We’ve had an remarkable run of sunny, rain-free days, and above average temperatures for much of May (and indeed even going back a couple of months), and while that’s translated to pleasant weather for outdoor activities, it also has meant that we’ve entered into a stretch of moderate drought. We had a stretch of no rain for 23 consecutive days, earlier this month, which definitely didn’t help things. According to the USDA Drought Monitor, Central Park recorded 7.12″ of rain from March 1st through May 19th, which is only about 63% of average for this time of year.
While we are only in the lowest tier of drought and were just added to this category this week, these drought conditions bear watching. We hope to get some rain out of this week, and it looks like more storms are on the way this weekend, however, the drought forecast for our region looks to have the drought persist through this summer.
This will be my last post for another few weeks as I will be traveling in South America. This week, we have an active weather pattern that will lead to a series of periods of rain. Mid-week, temperatures will be well below normal (mid-40s), but towards the end of the week, through the weekend, and to begin next week, temperatures will rebound to slightly above normal (low 60s).
Today – we’ve already had a round of light to moderate rain pass through earlier this morning. The rest of the day will feature temperatures falling through the 50s, along with overcast skies and a light onshore flow. A second round of rain looks set to hit the area around the evening rush hour today.
High Resolution Rapid Refresh model output for 5PM today.
Wednesday – a raw, rainy, and cold day is in store tomorrow. A stationary front (the reason for the extended period of unsettled weather) will push through late Tuesday as a cold front. This will allow for much colder air from Canada to enter the area, which will lead to temperatures only in the mid-40s (10-15º below normal). Periods of rain are likely throughout the day and into the night.Thursday – essentially a repeat of Wednesday, with chances for rain through out the day, and cold, cloudy conditions otherwise. High temperatures again only in the mid-40s.
Friday – chances for rain continue through Friday as a warm front will be approaching from the south. Once this front pushes through, we’ll see a return to milder temperatures with highs in the low 60s (about 5-8º above normal).
The Weekend – conditions finally begin to improve on Saturday with a cold front having pushed through. Chance for precipitation dwindles, with highs in the low 60s. Sunday is even better with clear skies and warm temperatures near 60.
Warm Trend for Next Week
Climate Prediction Center has our region in an area of greater than 50% chance of above average temperatures for next week. This should translate to pleasant, spring like conditions for next week!
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.
Another cold weekend is on tap for the area, before the start of a week of active weather. It does appear that March will be coming in like a lion this year.
Rest of today – some sun, with a chance for light flurries and a high in the mid-20s.
Friday – diminishing clouds with a high temperature again in the mid-20s. High pressure begins building to our west, yielding northwesterly winds that will allow chilly, Arctic air to filter back into the area. Overnight lows Friday will be in the low teens.
Saturday – with high pressure to our west still firmly in control, it will be a sunny, but cold day, with highs again only in the mid-20s.
Sunday – clouds will be increasing ahead of an approaching storm system and as high pressure exits to the east. There will be a slight warmup ahead of the storm, with temperatures topping out near freezing. Snow likely overnight, although significant accumulations are not expected.
Monday – temperatures will warm potentially into the low 40s on Monday as warm air from the southwest gets pulled into the storm system. There may be some mixed precipitation along the coastal plain, with all snow elsewhere, mostly early in the day.Tuesday – following the passage of the storm on Monday, temperatures dip back to around freezing, ahead of another storm system that will be impacting the area Tuesday into Wednesday. This storm has a greater potential significant precipitation.
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.
The low overall snowfall totals for NYC yesterday wasn’t so much a problem as the significant icing that resulted from an extended period of freezing rain. Ironically, a week the city government took criticism for shutting down the transit system for blockbuster blizzard that did not come to pass here, it was 1/4″ coating of ice that wreaked havoc on the entire transit system (the hours long complete suspension of the 7 train was an extreme example of this). We do get a couple more shots at snow, once tomorrow night into Thursday, and then again during the weekend, but at this time neither event looks to be nearly as high impact as what we’ve experienced the last two weeks.
Wednesday – will be comparatively mild in the context of the rest of the week and the weather we’ve had recently. High temperatures may actually even hit 40 (slightly above normal). However, as a cold front approaches from the west, we’ll have an increasing chance for snow showers, which maybe mixed with rain at the coast during the earlier part of the evening.
Thursday – chance for snow showers continues along the vicinity of the frontal boundary as it passes over us. Following the passage of that cold front, temperatures take a serious drop as northwest winds allow for Arctic air to make a comeback into the area. Lows overnight Thursday could be as low as the single digits for the city and below zero for outlying suburbs. Coupled with a northwest wind of 15-20mph, this would produce dangerously cold wind chill values.
Generally low snowfall totals expected across the region from this event
Friday – high pressure builds in briefly for Friday, giving us the only guaranteed dry day through the forecast period. It will still be cold with highs only in the low 20s.
Saturday – an arctic front will be approaching during the day Saturday, and ahead of the front, we’ll actually about normal temperatures in the upper 30s due to southwest flow. Clouds build in and the chance for snow showers builds during the later part of the day into the overnight.
Sunday – the arctic front mentioned above moves over us but then it looks like it will stall in our vicinity for an extended period from Sunday into Monday. High temperatures will cool to around freezing in the wake of that frontal passage.
At this time, it’s too early to know exactly how much snow we would pick up. It does appear that the precipitation with this system will be generally on the lighter side, except as the low pressure center depicted over southern Illinois in the graphic below approaches the coast. Once it arrives just west of the coast, it could draw in some moisture off the ocean as the counterclockwise cyclonic flow around the eastern periphery of the low induces an extended period of onshore flow (like a sea breeze, except in this case, the air over the water is actually warmer than it is over the snowpack on the land). If this onshore flow is robust enough, it could warm coastal areas up enough to get some rain out of the storm.
Stationary arctic frontYou can see the distinct separation between warm and cold airmasses demarcated by the stationary front depicted in the image above – the front separates the areas with the blue dotted lines from the areas of the warm dotted lines.
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!
