Monthly Archives: September 2014

NYC Weather Update – Sept 30, 2014

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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
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

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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.
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

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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.

Forecast for Sunday, 9/21
Forecast for Sunday, 9/21

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

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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
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.

GFS 500mb vorticity and height model output. Note the two areas of very strong vorticity and closed heights in the Atlantic and Eastern Pacific corresponding to two tropical systems.
GFS 500mb vorticity and height model output. Note the two areas of very strong vorticity and closed heights in the Atlantic and Eastern Pacific corresponding to two tropical systems.

NYC Weather Update – Sept 9, 2014

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This week features a rather active pattern, with several chances for precipitation starting with today.

Tuesday – there is some small chance for scattered rain showers today associated with an area of low pressure that is currently located over North Carolina. However, this chance of rain will be primarily confined to areas south of the city. As the area of low pressure slowly moves offshore of the Mid-Atlantic states, the pressure gradient will strengthen, allowing for a persistent easterly wind to continue transporting cool, maritime air into the region. Temperatures will remain on the cool side, with highs similar to yesterday in the mid-70s.

Wednesday – conditions will improve somewhat as the aforementioned area of low pressure exits east over the Atlantic. We will still not be able to escape a cool, onshore wind from the northeast, so even though clouds will diminish, high temperatures will again struggle to reach 80.

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Cold front approaches on Thursday

Thursday – the most substantial chance for rain this week will arrive with the passage of a cold front late in the day Thursday into the overnight hours. Warmer air from the southwest ahead of the cold front will translate to about average high temperatures in the low 80s under cloudy skies. As the cold front nears, showers and some thunderstorms will be possible. Current timing of the forecast models suggest that the bulk of the rain will not arrive until the evening hours.

Friday – conditions will improve Friday as high pressure builds in again in the wake of the cold front passing Thursday. Temperatures will drop back into the mid-70s with cooler, Canadian air filtering in from the north behind the front.

Tropical Storm Edouard?

Tropical wave off the coast of Western Africa
Tropical wave off the coast of Western Africa

A vigorous tropical wave moved offshore of Western Africa earlier this week, and is being monitored for possibility of tropical storm formation later this week. Environmental conditions are forecast to remain favorable for development with low wind shear and warm sea surface temperatures. This storm may bring some impacts to the East Coast of the United States, but it is too early at this point to know the scope of that impact.

 

NYC Weekend Weather Update – Sept 4, 2014

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We’re still in the grips of a warm and humid airmass, despite some cooling off last night due to the passage of a weak cold front. This warm trend will not break until a stronger cold front passes through the region on Saturday.

Friday – expect high temperatures once again in the mid-upper 80s, albeit with increasing cloud cover as stratus cloud decks start to filter in ahead of the aforementioned cold front.

GFS model output for 2PM EDT Saturday
GFS model output for 2PM EDT Saturday

Saturday – unfortunately, the timing of the cold front above does mean it will bring adverse impacts to our weekend plans. Showers and thunderstorms are likely to precede and accompany this frontal passage, particularly later in the day Saturday into Saturday evening. High temperatures ahead of the front will remain warm in the mid-80s, somewhat cooler near the shore. There will be a noticeable cooling with this round of storms.

Sunday – Clouds will diminish through the course of the day Sunday as a much cooler regime works its way into the area. High temperatures will only be in the upper 70s for Sunday and the beginning of the weak.

Monday – Skies will be mostly clear, and temperatures will be much cooler in comparison to Labor Day, with highs only in the upper 70s (~10 degrees cooler than Labor Day). High pressure building over us will lead to an onshore wind flow, bringing in a cool, maritime polar airmass.

Cool onshore flow due to high pressure Monday
Cool onshore flow due to high pressure Monday

 

NYC Weather Update – Sept 2, 2014

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Despite the unofficial end of summer, today may very well turn out to be one of the hottest days of the summer! We’re looking at forecast high temperatures in the upper 80s into the lower 90s across urban areas. Some relief will be possible with afternoon thunderstorms, and then another round of showers and thunderstorms overnight. A few of these storms could be approach severe limits, however, despite the heat and humidity, atmospheric dynamics are not favorable for widespread severe weather.

Cold front passing through overnight could give some temporary relief to the heat
Cold front passing through overnight could give some temporary relief to the heat

Wednesday – despite the passage of the cold front above, temperatures will remain warm and humid with highs in the mid-upper 80s under sunny skies.

Thursday & Friday – essentially the same, hot, humid, sunny with highs in the mid-upper 80s. The culprit will be an area of high pressure that moves offshore and to the southeast Thursday. This setup will allow for hot, humid air from the Southeast of the country to pump into the area.

High pressure southeast of us allowing for hot, steamy air to enter the area.
High pressure southeast of us allowing for hot, steamy air to enter the area.

The Weekend – we’ll finally see the heat break later Saturday and into Sunday as a stronger cold front brings in a cooler, drier Canadian airmass.