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NYC Weather Update – Nov 11, 2014

November 11, 2014Climate, NYC, Rain, Snow, Weather Update, Weekendarctic air, arctic oscillation, climate, cold, cold weather, fall, new york weather, nyc weather, nyc wx, rain, snow, winterLei Zhao

I hope you all took advantage of this gift of incredibly warm weather that coincided with a federal holiday, because that’s going the be the last gasp of mild weather for at least the next 7-10 days. As you probably heard, we are going to get walloped by an arctic airmass the latter half of the week that will bring an abrupt end to fall temperatures and make it feel like we jumped straight into winter – I’m talking high temperatures that won’t even get out of the low 40s by week’s end. Before you ask, no this is not a polar vortex – it will be damn cold nonetheless.

Wednesday – this will be the last day we get above 60 degrees for quite a while. We are currently in a warm sector in between a warm front that pushed through earlier this week and ahead of a cold front that will be open the door to an arctic airmass swinging down from Canada. High temperatures in the Central Plains and Intermountain West where this airmass has already taken hold are ranging from the teens to the 30s. But Wednesday, we’ll still be in the mid-60s, although it won’t be as pleasant as today with a foggy and cloudy start to the day. Once the cold front below passes, clouds should clear quickly and lead to excellent conditions for radiational cooling, with low temperatures dropping into the low 40s and into the 30s in the interior areas north and west.
Thursday – it won’t be that cold just yet, with high temperatures still expected to hit the low 50s. But clouds will again increase ahead of a second, quick-moving storm system that is expected to pass through Thursday night into Friday. This will be the real arctic sledgehammer that brings seriously cold air into the region. There will be enough energy and moisture in the atmosphere for the possibility of rain/snow mix on Thursday night and even all snow in the city Friday morning.

Friday – skies should clear quickly during the day Friday, but despite all the sun, temperatures will struggle to hit the mid-40s. Arctic air will be firmly entrenched from this point on until as long as Thanksgiving!

Saturday – High pressure will be in control Saturday, high temperatures will have a difficult time hitting 40 though, because the setup of the high will favor northerly winds. Sunday – yet another storm system brings us the chance for some precipitation. Behind that system – you guessed it, more cold air and temperatures that will be two standard deviations below normal for this time of year, as per our local forecast office.

For those of you who are interested in the long-term outlook, based on forecast models and the arctic oscillation index forecast, it looks like this blast of cold air will be sticking around with us for at least the next 7-10 days, and may not break until Thanksgiving. The Arctic Oscillation measures the climate pattern of winds circulating at high latitudes close to the arctic. When it is in it’s negative phase (as is about to be the case, on the right end of all the charts below), higher pressure tends to dominate over the arctic while lower than normal pressure occurs in mid-latitudes (i.e. our area). Air tends to flow from areas of high pressure towards areas of low pressure, so this pattern sets up favorable conditions for the intrusion of bitterly cold air into our region.

NYC Weather Update – Nov 4, 2014

November 4, 2014NYC, Rain, Storms, Weather Updatecoastal storm, cold front, new york city weather, nyc weather, rain, rain storm, storm, warm front, weather, wxLei Zhao

Election Day features temperatures much above normal for this time of year, with high temperatures in the mid-60s under mostly sunny skies. Wednesday continues the warm trend but with increasing clouds. We’ll see another stormy end to the week before conditions improve this weekend.

Tuesday – the remainder of the day will feature high temperatures in the mid-60s reminiscent of early October and not November. This is all thanks to a warm front that passed through (you can see this in the diagram below for Wednesday, up and to the right of NYC demarcated by the red line). Go out and enjoy this while you can, and don’t forget to vote!

Wednesday – we’ll see an even warmer day despite the increase in cloud cover ahead of an approaching cold front. Southwesterly flow will allow warm, tropical air to surge into the area from the Gulf. This plume of warmth and moisture will also prime the atmosphere ahead of Thursday’s storm. The cold front itself will weaken as it passes, so we’re not anticipating any rainfall. High temperatures will be generally in the upper 60s.

Thursday – a storm system with its origins in the Great Lakes/Ohio Valley area will form a secondary low near the offshore waters of the Northeast. Despite being only 2 days out, there’s still some uncertainty to the ultimate track of this storm system. The general pattern will be somewhat similar to last week, with the coastal storm forming and then slowly making its way northeast. The availability of deep moisture suggests the possibility of bouts of heavy rain during the day Thursday into Thursday night. When all is said and done, we could be looking at rainfall totals in the 1.5″-2″ range across the area, depending on the final track of the storm. The further west the track, the further west the highest impact areas will be, and the inverse for tracks further east. High temperatures will remain mild until after the storm departs to the northeast, with high temperatures in the low 60s.

gfs_namer_072_1000_850_thick — GFS model output for Thursday

Friday – rain should end early Friday as the low lifts to the northeast. Winds will pick up and shift towards the north, resulting in much cooler high temperatures only in the mid-50s.

We get a cool but sunny Saturday before another chance of rain Sunday.

NYC Weather Update – Oct 28, 2014

October 28, 2014NYC, Rain, Snow, Weather Update540 height, autumn, cold, nyc weather, nyc wx, snow, weather, winter, winter wxLei Zhao

Summary

This week will be archetypical of autumn weather, with large temperature swings in store for the region. We’ll start off with highs more characteristic of late summer near 70, though with clouds overhead, we may not top that number. A weak cold front will push through tomorrow with some chance of showers. Behind this front, temperatures will drop to more seasonable highs around 60 with dry conditions. The week ends like winter with an arctic airmass invading the region, leading to the possibility of snow and high temperatures only in the upper 40s.

Wednesday – clouds build in and showers will be possible for most of the day. Most rain should conclude by the evening hours. High temperatures will remain warm ahead of the passage of the cold front with winds from west pushing warm air ahead of the front.

Weak cold front passing through Wednesday, scattered showers possible.

Thursday – clear and sunny skies behind the cold front passing Wednesday, high temperatures cooler near 60. Overnight lows will be quite cool in the lower 40s with good conditions for radiational cooling.

Friday – clouds will increase ahead of the next storm system, and high temperatures will remain near 60.

Saturday – an intrusion of arctic air accompanying a strong, deep trough (cold front) will set the stage for what should be a raw, chilly, winter-like day. With the arctic air pumping in, high temperatures will struggle to even hit 50. In the chart below, you’ll see a height of 540 near us. Without going into too much detail, low heights generally correspond to colder temperatures, as colder air is more dense, it takes up less volume than the same mass of warmer air. A height of 540 is considered by forecasters to be important when determining precipitation type, as it indicates temperatures cold enough to support snow. That’s right – we will probably see some snow north and west of the city, and depending on the track of a secondary low that forms Saturday along the coast, we could even get some of the white stuff in NYC. This is a complex system, so it will bear watching over the next couple days.

NYC Weekend Weather – Oct 24, 2014

October 24, 2014Noreaster, NYC, Storms, Weather Update, Weekendhigh pressure, new york city weather, noreaster, nyc weather, nyc wx, rain, weather, wx, wx forecastLei Zhao

We are still feeling the impacts of that Nor’easter that passed through Wednesday and Thursday. There will be some lingering showers east of NYC this morning, before gradual things begin to dry out and skies gradually clear from west to east. High temperatures will be in the mid-60s, but with a north wind blowing, it will still feel quite cool. We’ve got an excellent, fall weekend on tap.

Saturday – we’ll get sunny skies again, and high temperatures will remain in the mid-60s.

Sunday – much the same as Saturday.

Monday – high pressure will continue to build to our south. This will mean a shift in winds to the south and southwest, which will open the door for warmer air to stream in from the south. High temperatures in the mid-upper 60s, under sunny skies.

Tuesday – as that high pressure strengthens, we’ll get another day of even warmer temperatures Tuesday with highs near 70. We’ll be watching for another storm system approaching from the west that could bring us a chance of rain Wednesday.

NYC Weather Update – Oct 14, 2014

October 14, 2014Flooding, NYC, Outside of NYC, Rain, Severe Weather, Storms, Thunderstorms, Tropical/Hurricanes, Weather Updatebermuda, cold front, flooding, gonzalo, hurricane fay, hurricane gonzalo, new york city weather, nyc weather, nyc wx, severe thunderstorms, severe weather, severe wx, weather updateLei Zhao

Apologies for the lapse in posts last week. There was plenty to talk about with the formation and dissipation of Hurricane Fay, and with Hurricane Gonzalo developing. Gonzalo won’t be a threat to the U.S. mainland, but may wreak havoc in the vicinity of Bermuda as a low end Category 3 storm with 115-120mph sustained winds. This storm has the potential to hit Category 4.

Back to our region:

Today – we get to enjoy a very warm day for this time of the year with highs in the mid-upper 70s and sunny skies! Unfortunately, clouds will begin spreading over the area in a few hours time ahead of a system described in detail below.

Wednesday – there will be a chance of light rain in the morning, with the chance for more substantial rainfall increasing in the afternoon. Temperatures will remain mild in the mid-70s with persistent southeasterly flow channeling in warm, moist air from the south ahead of the cold front and storm system that was responsible for a severe weather outbreak in parts of the Midwest and Southeast earlier this week.

Thursday – will be the main event. Lucky for us, the storm system coming at us won’t be bringing severe weather, however, a thunderstorm or two is not out of the question. The main issue for us will be the risk of flooding from this slow moving system. Forecast models show training of storm cells, meaning the same areas will get hit repeatedly or continuously with moderate rain showers. Rain will likely be falling throughout the entirety of the day Thursday with little or no breaks. Rainfall totals of nearly 2″+ could lead to some minor flooding. However, the rain is welcome since we are nearly 3″ below average for rainfall. Temperatures should again remain on the warm side with highs in the mid-70s.

NAM high resolution model output for Thursday, Oct 16 @5PM – note the bright blue and purples stretched over the area, indicating bands of heavier rain

Precipitation total forecast for 8PM Wednesday-8PM Thursday. Nearly 2" for the NYC area. — Precipitation total forecast for 8PM Wednesday-8PM Thursday. Nearly 2″ for the NYC area.

Friday – things settle down quickly as a brief window of calm weather enters the picture. Temperatures will be cooler in the wake of the cold front with west winds and highs in the lower 70s.

NYC Weekend Weather – Oct 2, 2014

October 3, 2014NYC, Rain, Storms, Thunderstorms, Weather Update, Weekendautumn, bikems, bikemsnyc, cold front, gfs, nam, nyc weather, rain, thunderstorms, triple point, warm front, weather update, weekend weather, weekend wxLei Zhao

Friday and Sunday will be the sunny and pleasant bookends to what will be a stormy and rainy Saturday this weekend.

Today – we’re looking at sunny skies and high temperatures in the low 70s. Clouds will begin to build back in later in the evening as the storm maker for Saturday begins to move in from the west.

Screen Shot 2014-10-03 at 8.00.54 AM — NAM high resolution model output for Saturday at 10AM EDT

Screen Shot 2014-10-03 at 8.01.47 AM — Weather Prediction Center forecast map for Saturday

Saturday – a negatively tilted frontal system will be moving over the area Saturday, with the worst of the rain coming between about 10AM-3PM. We will be in the vicinity of a triple point (junction between a cold, stationary, and occluded front, this feature is common with mature mid-latitude cyclonic systems) that will be draping south from a strengthening low pressure center that will be moving northeast into Ontario during this timeframe. A thunderstorm is not out of the question given the atmospheric dynamics. Temperatures should hover around the 70 degree mark despite the cloud cover and rain because of the potential for us to briefly enter a warm sector between the stationary front and cold front.

Sunday – we get a crisp blast of autumn air behind the frontal system passing through Saturday. Sunshine returns just in time for the annual BikeMS NYC, which yours truly will be participating in. Cool temperatures will be only in the mid-upper 60s.

Monday – good weather sticks around for the start of the work week with high temperatures around 70.

Our next chance for precipitation should come Tuesday-Wednesday. The low pressure center responsible for the rain Saturday is forecast to close off and retrograde (move west instead of east, with prevailing upper level winds) over central Canada. An impulse of energy will rotate around this center and lead to another cold front passing through our area.

NYC Weather Update – Sept 30, 2014

September 30, 2014NYC, Rain, Storms, Weather Updatecold front, gfs, negatively tilted trough, new york city weather, nyc weather, nyc wx, stationary front, weather, weather forecast, wx forecastLei Zhao

The skies look gloomy today, but there’s not a high chance of precipitation as the best dynamics for showers remain mostly offshore and to the east. High temperatures will be a bit above average with high temperatures in the low 70s.

Wednesday the chance for scattered showers will remain with a stationary frontal boundary slow to push south through our region. The best chance for precipitation will again lie to the east, likely well away from the city. High temperatures will be somewhat cooler around 70 with mostly cloudy skies.

Thursday – following the passage of the frontal boundary above, high pressure will build in from the north. Cloud cover should decrease gradually though not entirely clearing, but northeast and easterly wind will lead to cooler temperatures with highs only nudging the 70 degree mark.

Friday should be much the same as Thursday, with high temperatures right around 70 and clouds & sun.

GFS model output for Saturday, Oct 4, 2014

Saturday – the forecast models are unambiguous in anticipating the passage of a negatively tilted cold front through the region (negative tilt in the northern hemisphere would correspond to a frontal boundary where the northern end lies to the west of southern end of the boundary, these types of fronts are often associated with higher levels of instability). Temperatures will be cool in the upper 60s to around 70, with a period of steady showers likely at some point during the day, right now it’s looking like this will be during the morning hours.

NYC Weather Update – Sept 23, 2014

September 23, 2014Noreaster, NYC, Rain, Weather Update, Weekendautumn, coastal low, cold front, fall, noreaster, nyc weather, nyc wx, rain, rosh hashanah, weatherLei Zhao

Today marks the first day of astronomical autumn, and it has been feeling ever more fall-like the past few days.

Wednesday – the day should start off partly cloudy, and high temperatures will sit at right about 70. However, with a coastal low forming off the Mid-Atlantic, cloud cover will increase especially later in the day.

NAM high resolution model output for Thursday, 9/25 @ 11AM EDT.

Thursday – a slow moving coastal low (technically a Nor’easter) will be moving over the NYC region during the early morning hours Thursday and throughout the course of the day itself. With the low pressure center just to our south or southeast, we should see a cool northeast wind off the ocean. This will limit high temperatures to only the upper 60s under cloudy skies and periods of rain.

Friday – with this coastal low out of the way, high pressure will take control again and clear the way for a superb start to the Rosh Hashanah weekend. Highs on Friday should bounce back nicely into the mid 70s under clearing skies.

Screen Shot 2014-09-23 at 6.40.40 PM — GFS model output for Saturday, 9/26

Saturday – high temperatures will continue climbing to nearly 80 on Saturday under clear skies.

Sunday – pretty much a carbon copy of Saturday. High near 80.

The next chance at rain will be next Tuesday with a cold front approaching us from Canada.

NYC Weather Update – Sept 17, 2014

September 17, 2014NYC, Weather Update, Weekendcold front, cool, nyc weather, nyc wx, warm front, weather update, weekend weatherLei Zhao

It’s going to be a quiet weather week after the rain that passed yesterday. For the remainder of the week, high pressure will keep conditions fair and sunny, despite the passage of a weak cold front tomorrow. Temperatures today and Thursday should be in the mid-70s. There will be a slight cool-off Friday after the passage of that weak cold front, but things will warm back up this weekend.

Saturday – high temperatures will be in the mid-70s, partly cloudy skies.

Sunday – a warm front will pass through early Sunday and allow for temperatures to climb to about 80. Clouds will increase as a trailing cold front approaches. No precipitation forecast at this point, but I wouldn’t be surprised if there were a couple light showers with this front.

Get ready for the official start of autumn! Monday marks the autumnal equinox, the point at which night and day are about equal in length. From here on out, our days will be getting shorter and shorter, so try and get out there to soak in some rays and get some vitamin D in you.

NYC Weekend Weather – Sept 12, 2014

September 12, 2014NYC, Rain, Storms, Tropical/Hurricanes, Weather Update, Weekendcanadian air, cool temperatures, nyc, nyc weather, nyc wx, rain, weather, weekend weatherLei Zhao

Although the passage of a cold front yesterday didn’t bring any precipitation with it, you can definitely feel its impact in the form of much cooler and drier air today. Temperatures will be in the low 70s today with crisp, clear skies above.

Saturday – cloud cover will build tonight as an area of low pressure originating from the Tennessee Valley area slides along the frontal boundary that’s now located offshore to our east. This low pressure system will bring a solid chance at rain tomorrow especially later in the day into the evening hours. High temperatures will be cool, around 70, under cloudy skies.

NAM high resolution model output for Saturday evening at 8PM

Sunday – luckily, this storm system will exit rather quickly to our east, making Sunday an excellent day for outdoor activity of all varieties. Temperatures will be on the cool side, with highs in the low 70s under partly cloudy skies.

Monday – this week begins a trend towards cooler, fall-like temperatures as an upper air pattern favoring the intrusion of a cool, Canadian airmass takes hold. Highs on Monday will again only be in the low-70s, about 5 degrees cooler than average for this time of the year.

Tuesday – brings us our next shot at rain, as a weak impulse of energy passes through. The rest of the week after Tuesday looks like it will be uneventful, albeit on the cool side with the aforementioned arrival of a Canadian airmass and high pressure.

LZ | Weather

Weather updates & posts for NYC region