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NYC Weather Update – Dec 29, 2020

December 29, 2020NYC, Rain, Storms, Weather Updatecold front, downslope winds, high pressure, new york city weather, new york city wx, nyc weather, nyc wx, rainLei Zhao

Messy weather ahead going into the New Years holiday for NYC. We start with high pressure moving overhead. This then gives way to a frontal system tomorrow night. After a brief lull, another storm, similar in some ways to the Christmas storm comes in Friday. Both these precipitation will be rain in the city. Temperatures during this period will generally be above normal in the 40s, warming into the mid-upper 40s.

Rest of today – partly cloudy with high temperatures around 40ºF. Clouds will be streaming in from the northwest, originating from the Great Lakes as lake effect snow showers. These clouds will tend to thin out as northwest flow downslopes dries out across the higher terrain north and west of the city. This northwest flow could also result in some strong wind gusts. With strong high pressure forecast to move nearly directly overhead tonight, winds should calm with skies becoming mostly clear. This will favor good radiational cooling, leading to cold overnight lows in the mid-20s.

GOES Geostationary Satellite visible imagery this morning showing clouds streaming off the surface of the Great Lakes towards the East Coast.

Wednesday – partly cloudy with high temperatures again around 40ºF. Overnight, a warm front passes, followed by a cold front. This will result in an increase in temperatures overnight from the mid-30s as well as rain.

Thursday – a mild day despite the passage of the cold front mentioned above, with forecasters noting the air mass behind the front being of milder Pacific origin. High temperatures around 50ºF. Rain chances should diminish quickly after the morning passage of the cold front. The respite will not last too long as the next storm system follows up quickly. Overnight temperatures dropping into the low-30s.

ECMWF “Euro” model 24 hour quantitative precipitation forecast ending 7AM Saturday, about .70″.

Friday – high temperatures in the mid-40s with another storm system approaching. Rain chances increase going into the overnight hours. This storm, like the Christmas storm, is expected to deliver some moderate to heavy rain. However, since it’s forecast to be weaker overall, the winds and precipitation totals shouldn’t be nearly as robust as the last storm. Overnight should shape up to be similar to Wednesday, where temperatures may actually increase into the upper-40s with the passage of a warm front and corresponding warm air advection.

NYC Weather Update – Dec 14, 2020

December 14, 2020NYC, Rain, Snow, Storms, Tropical/Hurricanes, Weather Updatecoastal storm, high pressure, new york city weather, new york city wx, nyc weather, nyc wx, rain, snow, snowstorm, winter stormLei Zhao

A quick hitting storm passes south of the city today bringing some rain and mixed precipitation, with no accumulating snow expected. Colder temperatures then take hold in the mid-30s behind this storm Tuesday as a strong area of high pressure builds over Quebec. This sets the stage for a potentially significant snowstorm developing Wednesday into Thursday with 8″+ totals possible along the I-95 corridor (with higher amounts north and west). However, there is still a good deal of uncertainty with the eventual track of this storm that could result in large differences in outcomes.

Rest of today – temperatures dropping through the low-40s into the 30s with mostly cloudy skies and a steady, chilly rain, possibly mixing with some wintry precipitation. No accumulation is expected. Overnight lows around the freezing mark with precipitation ending as high pressure begins building in.

Weather Prediction Center surface forecast for 1PM Monday. An area of low pressure is seen exiting the east coast, bringing us a period of rain and possible mixed precipitation, with snow further inland.

Tuesday – proverbial calm before the storm as high pressure dominates, giving us a mostly sunny day with high temperatures around 40ºF. Overnight lows again in the upper-20s with cold northerly winds flowing around the east side of this high.

Wednesday – high pressure yields to a developing coastal storm. Partly sunny to start with increasing clouds. High temperatures in the mid-30s. Overnight lows drop into the mid-20s. The big story is the potential for a significant snowstorm with accumulations possibly over 8″. GFS and the Euro model have come into agreement for much higher totals, 14-15″. However, NAM shows a warmer scenario with warmer air working further north, thus cutting into overall totals (only 7″). It’s also possible that the low tracks close enough to shore that we end up with a good deal of rain mixing in at the coast, cutting snow totals even further.

Part of the energy fueling this storm is coming all the way from a shortwave with origins over the Pacific Ocean. This has only just made landfall in the US today. As this energy gets sampled by upstream soundings (weather balloon launches) and other means, the forecast models should get a better sense for how this storm will evolve. At this time, there’s enough uncertainty in the forecast to still not buy into any specific totals. If you look below, you can see there’s a lot of spread in the models in terms of the track of this storm. This then translates to a wide range in ensemble forecast totals. In addition, with a coastal storm like this, where there’s a lack of deep, Arctic cold air ahead of the storm, there’s a sharp gradient between areas where the event would be all snow vs. a mixed event. If you see the 24 hour probabilities of > 8″ accumulation, you can see that a 50 mile shift in the storm track further south and east would give us much higher chances for big snowfall totals, while a shift the other way could result in a bust on snow totals. Suffice to say, this storm will bear close monitoring today and tomorrow as more data comes in and models have a chance to digest it.

ECMWF “Euro” model surface pressure, precipitation and type for 1AM Thursday

Weather Prediction Center probabilities of > 8″ total accumulation in 24 hours leading up to 7AM Thursday

Thursday – depending on the speed and track of the storm, we could see precipitation lingering into the morning hours, with additional accumulation possible. Highs should hover around the freezing mark. Overnight lows drop into the mid-20s with reinforcing cold air advection on the backside of the departing storm.

NYC Weather Update – Dec 7, 2020

December 7, 2020NYC, Rain, Tropical/Hurricanes, Weather Updatecold front, high pressure, new york city weather, new york city wx, nyc weather, nyc wx, rainLei Zhao

A week of contrasts is in store for us with colder than average temps in the low-40s to start things off. However, a warming trend will take hold as a more zonal flow evolves at the upper levels, moderating heights and temperatures. This will result in milder conditions later on in the low-50s.High pressure and dry northerly flow should keep things rain-free until closer to the weekend.

Rest of today – below normal high temperatures around 40ºF with increasing clouds as a low pressure center passes well off to our southeast over the Atlantic. The presence of this storm offshore will result in persistent northerly winds, though less potent than over the weekend. Overnight lows in the low-30s.

Weather Prediction Center surface forecast for 7PM Monday. Note the presence of a low pressure center east of North Carolina.

Tuesday – high pressure briefly builds in and provides a mostly sunny day but with temperatures still only peaking around 40ºF. Overnight lows again in the low-30s.

Wednesday – high temperature start to rebound towards normal in the mid-40s with partly sunny skies as a storm passes well to our north, and we end up in the storm’s warm sector. Overnight lows drop into the upper-30s.

GFS model 500 mb temperature, height and winds forecast for 1PM Thursday. Flow at this level is forecast to become more zonal (flatter) than earlier this week.

Thursday – temperatures jump into the low-50s with sunny skies as high pressure briefly moves in again and upper level flow starts to flatten out resulting in the colder air mass in place to start the week getting pushed north. Overnight lows in upper-30s.

NYC Weather Update – Nov 16, 2020

November 16, 2020NYC, Rain, Tropical/Hurricanes, Weather Updatecold front, high pressure, new york city weather, new york city wx, nyc weather, nyc wx, rainLei Zhao

What a big contrast in sensible weather this week vs. last! We were looking at record-breaking warmth in the upper-70s this time last week. Now, in the wake of a strong cold front and severe storms yesterday, temperatures cool off into the low-50s to start the week. A reinforcing cold front and high pressure brings much below normal highs only in the low-40s mid-week. A round of quick snow showers is possible going into Tuesday morning!

Rest of today – seasonably cool with westerly winds starting to die down. Sunny with high temperatures around 50ºF. Overnight lows in the upper-40s.

Weather Prediction Center surface forecast for 7AM Tuesday

Tuesday – clouds increasing as a cold front moves in from the northwest. High temperatures steady in the upper-40s. Chance of rain then rain and snow overnight. Overnight lows below average in the low-30s.

Wednesday – due to a cold start, and high pressure to the southwest, northwesterly winds will keep things cold on Wednesday with highs only around 40ºF despite sunny skies. Overnight lows drop into the low-30s.

Thursday – temperatures increase to the upper-40s with sunny skies. Overnight lows warming into the low-40s.

Hurricane Iota – A Major Disaster for Central America

A catastrophic disaster could be unfolding for Nicaragua and Honduras, in the same regions that were pummeled by Hurricane Eta barely two weeks ago. Hurricane Iota appears to be on its way to becoming a rare November Category 5 storm, and is looking very impressive on satellite images this morning. The torrential rain this storm brings could result in landslides, and inland flooding, exacerbated by soil that’s still quite damp from Eta’s onslaught. With recovery efforts ongoing, and people still without permanent shelter, Iota could be a major, life-threatening storm for this area.

GFS model 850 mb relative humidity and winds at 1AM Thursday, depicting some decently fast winds and ample moisture accompanying the cold front.

NYC Weather Update – Nov 9, 2020

November 9, 2020NYC, Rain, Weather Updatecold front, new york city weather, new york city wx, nyc weather, nyc wx, rain, record temperaturesLei Zhao

The week starts with possible record breaking warmth carrying over from the weekend. Record high temperatures in the mid-upper 70s were set at several locations in the region yesterday. More records could fall today with highs in the mid-70s again. A general cooling trend takes place this week with highs eventually dropping back to seasonable levels in the upper-50s. A cold front mid-week with good moisture will bring a drenching rain Wednesday into Thursday.

Rest of today – very warm with possibly record breaking temperatures in the mid-70s once again under sunny skies. Overnight lows in the upper-50s with patchy fog possible.

Tuesday – temperatures cool off a bit but still quite warm in the upper-60s to near 70ºF with more clouds. Overnight lows quite mild in the low-60s.

Wednesday (Veteran’s Day) – increasing clouds but still warm with high temperatures approaching 70ºF. A vigorous cold front will be moving in from the west. Rain chances increase through the afternoon. Most of the rain should occur overnight with good moisture content accompanying this front. Overnight lows in only dropping into the mid-60s with warm, southerly flow ahead of the frontal passage.

Thursday – high temperatures occur early in the day prior to the passage of the cold front. Rain should subside as soon as the front passes. Behind the front, winds turn to the west and bring in a cooler, drier air mass. Temperatures should drop through the day with overnight lows bottoming out around 50ºF.

NYC Weather Update – Nov 2, 2020

November 2, 2020Climate, NYC, Weather Updatecold front, high pressure, new york city weather, new york city wx, nyc weather, nyc wxLei Zhao

A cold, windy start to the week will give way to a marked warming trend. Today and tomorrow, strong winds are likely, and the west-northwest direction of these winds will promote below normal temperatures in the mid-40s and low-50s. Beginning mid-week, warm, southwesterly return flow developing around a couple high pressure centers will induce temperatures to rise into the 60s, closing in possibly on 70ºF by this weekend. This 10-15ºF above normal warmth looks set to continue into the weekend and possibly early next week.

Rest of today – mostly cloudy with clouds diminishing towards the evening. Highs much colder than normal in the mid-40s with cold air advection still influencing our sensible weather due to strong west-northwesterly winds sustained at 25-30 mph gusting to possibly 40-50 mph early. This is all due to the tight pressure gradient between a deepening low tracking over the Canadian Maritimes and a high pressure center further south. Overnight lows in the upper-30s.

Weather Prediction Center surface forecast for 8AM Wednesday

Tuesday – a secondary cold front pushes through early, possibly touching off a few showers in the morning. Winds still breezy, but not as strong as today. Mostly sunny skies with highs around 50ºF. Overnight lows around 40ºF.

Wednesday – sunny skies with southwesterly winds developing as high pressure builds northeast of us. This will allow for a much warmer day with highs around normal, near 60ºF. Overnight lows in the upper-40s.

Thursday – high temperatures continue trending up into the mid-60s with southerly winds and plenty of sun. Overnight lows in the low-50s. The warming trend continues into the weekend where we could see mid to upper-60s.

GFS model 850 mb temperature anomalies for 1PM Saturday. Very warm air will be in place over the region.

NYC Weather Update – Oct 13, 2020

October 13, 2020Climate, NYC, Rain, Weather Updatecold front, high pressure, new york city weather, new york city wx, nyc weather, nyc wx, rainLei Zhao

Rainy, cloudy conditions early today start giving way to high pressure as the low pressure offshore, remnant moisture from remnants of Delta, continues moving off to the east. High pressure takes hold mid-week with above-normal temperatures rising into the low-70s. Additional rain chances come towards the end of the week with another cold front forecast to pass Friday, leading to cooler low-60s over the weekend.

Rest of today – rain ending this morning with clouds sticking around and high temperatures in the mid-60s. Clouds diminish towards the overnight hours. Overnight lows in the low-50s with skies clearing.

Wednesday – high pressure in place with warmer temperatures around 70ºF under sunny skies. Overnight lows in the mid-50s.

Thursday – similar day to Wednesday, high temperatures a touch warmer in the low-70s, with sunny skies. Overnight lows in the upper-50s with increasing clouds.

GFS model 2-meter above ground temperature anomalies for 8AM Friday

Friday – rain moves in especially later in the day and overnight. High temperatures still quite mild in the upper-60s with warm southerly flow ahead of the frontal passage. Overnight lows cool to around 50ºF following the frontal passage bringing rain.

NYC Weather Update – Oct 6, 2020

October 6, 2020Climate, NYC, Rain, Thunderstorms, Weather Updatecold front, new york city weather, new york city wx, nyc weather, nyc wx, pressure gradient, rain, thunderstormsLei Zhao

This week, we see slightly above normal temperatures in the low-70s to start off, dropping to below normal temperatures in low-60s later in the week following the passage of a cold front mid-week. Overall sunny conditions punctuated by this frontal boundary tomorrow. Gusty winds and a stray thunderstorm could accompany this front as its parent low deepens over the Canadian Maritimes.

Rest of today – mostly sunny with high pressure exiting to our south, yielding light southwesterly flow and high temperatures in the low-70s. Overnight lows in the upper-50s.

Wednesday – slightly warmer with warm southwesterly flow ahead of the cold front, highs in the mid-70s. Overnight lows in the mid-50s behind this front, which could bring isolated showers and thunderstorms to the area. Gusty winds could also accompany this front due to the large pressure gradient between us and its parent low moving over the Canadian Maritimes.

GFS model surface pressure and 10 meter above ground winds for Wednesday at 8PM

Thursday – Canadian high pressure sweeps in behind the cold front bringing sunny skies and cooler temperatures in mid-60s. Overnight lows much cooler, in the upper-40s due to this change in air masses.

Friday – with a cold start, high temperatures will likely top out in the mid-60s again under sunny skies. Overnight lows warm up into the low-50s.

NYC Weather Update – Sept 29, 2020

September 29, 2020Climate, NYC, Rain, Thunderstorms, Weather Updatecold front, new york city weather, new york city wx, nyc weather, nyc wx, rain, thunderstormsLei Zhao

Apologies for the lack of updates lately. Have had a few things going on keeping me busy. We have a wet beginning to October on the way with tropical moisture accompanying a slow moving cold front. Heavy rain is possible overnight Tuesday, with isolated flash flooding a concern. Temperatures should be around normal (low-70s) until this weekend when a reinforcing cold front brings us down into the mid-60s.

Rest of today – cloudy with chances for rain increasing later in the day as a cold front approaches from the west. High temperatures in the mid-70s. This latter frontal boundary may also spark some showers overnight, with temperatures dropping into the mid-60s. A strong low level jet will be in place overnight, enabling efficient transport of tropical moisture from the south. This will lead to the potential for rounds of moderate to heavy rain, where some training is possible as well. Flash flooding is a concern as places could see 1-2″ of total rainfall overnight. Winds could also be gusty in some of the heavier downpours, which could also produce some thunder. Temperatures generally in the mid-60s.

Weather Prediction Center surface forecast for 2AM Wednesday

Wednesday – conditions should improve during the day with showers diminishing in the morning. Mostly cloudy with highs in the low-70s. Subsidence (sinking air) with westerly winds could produce gusty winds. Overnight lows in the upper-50s with mostly clear skies.

Thursday – partly sunny with highs in the low-70s. Overnight lows in the mid-50s.

Friday – partly sunny with highs in the mid-60s. Chance for rain with another cold front forecast to move through. Overnight lows in the low-50s as temperatures start to cool off behind this frontal passage.

Looking ahead, behind this cold front, a period of below normal temperatures is forecast to hit much of the Eastern US next week.

NYC Weather Update – Aug 17, 2020

August 31, 2020NYC, Rain, Thunderstorms, Tropical/Hurricanes, Weather Updatecold front, new york city weather, new york city wx, nyc weather, nyc wx, rain, thunderstorms, tropical weatherLei Zhao

This week we will see a possibility of an extended period of cloudy weather, punctuated by periodic storms. This regime will bring cooler than normal temperatures mostly in the low-80s. Good news: Labor Day weekend looks to be dry and cool so far! Looking to the tropics, we’re about to enter the peak of hurricane season, and it’s no surprise in this very active season to date to see that National Hurricane Center is monitoring four disturbances that could become tropical storms.

Rest of today – cool, generally cloudy with possible peaks of sun, high temperatures in the upper-70s. Temperatures will be cool due to a persistent onshore flow with an area of high pressure over the Canadian Maritimes and a slow-moving warm front/stationary front to our south. This latter frontal boundary may also spark some showers overnight, with temperatures dropping into the mid-60s.

Weather Prediction Center surface forecast for 8AM Tuesday

Tuesday – the cool, cloudy trend continues with high temperatures again topping out in the upper-70s. Showers may occur periodically during the day. Overnight lows in the upper-60s with chances of showers continuing.

Wednesday – the cloudy, rainy weather continues, though temperatures may be a touch warmer around 80ºF. Chance for showers and thunderstorms. Overnight lows in the low-70s as the warm front finally pushes through.

Thursday – cloudy, with a chance for showers, and warmer temperatures in the mid-80s. Overnight lows in the mid-70s. Shower chances persist overnight.

Watching the tropics

Keeping eyes on the tropics, given that we’re about to enter the peak of the season (September) when oceanic heat content tends to be the highest, providing the greatest potential fuel for storms. There are four disturbances in the Atlantic that could become tropical systems, however, none of them are an immediate threat to the US mainland.

LZ | Weather

Weather updates & posts for NYC region