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NYC Weekend Weather Update – Dec 19, 2014

December 19, 2014NYC, Precipitation Type, Rain, Snow, Storms, Weather Update, Weekendchristmas weather, high pressure, low pressure, new york city weather, nyc weather, nyc weekend weather, nyc wx, rain, snow, storms, weather, weekend weather, white christmas, wxLei Zhao

This weekend will feature about normal temperatures for mid-December, with a small chance of rain/snow on Sunday. Relatively quiet weather during the weekend will give way to an active weather pattern for the first half of next week, with a robust storm system arriving Christmas Eve (all rain, sadly, so no white Christmas for us here in NYC).

Saturday – high pressure currently in control of the weather will erode as it moves east. Clouds cover will increase with high temperatures around 40.

Sunday – easterly winds off the ocean in the wake of high pressure centered over Atlantic Canada will bring some slight chance for precipitation. The lower atmosphere is fairly dry, and is not primed with moisture for precipitation. If precipitation does materialize, temperature profiles are low enough that some snow flakes could be seen, but the overall impact will be negligible. High temperatures will be in the low 40s with cloudy skies.

Monday – a significant storm system will be approaching our region from the Central Plains. Forecast models point to a primary low pressure center over the interior of the country while a secondary low forms along the coast. Ahead of this storm system, some scattered showers could pass over the area Monday. Otherwise, expect a mostly cloudy day with high temperatures in the mid-40s.

Tuesday – coverage of precipitation will increase on Tuesday as that secondary low pressure center draws closer to the area. Warmer, marine air will be in place before a warm front passes over. This should ensure that temperature profiles remain warm enough to preclude the possibility of snow. Temperatures may rise to as high as the 50 degree mark Tuesday.

This early-mid week storm will cause some travel headaches for Christmas, but fortunately, it does appear the majority of precipitation will be in the form of rain.

NYC Weather – Pre-Thanksgiving Storm Back On

November 24, 2014Uncategorized40 70 benchmark, coastal low, coastal storm, meteorology, new york city weather, noreaster, nyc thanksgiving weather, nyc weather, nyc wx, snow, snow storm, thanksgiving, thanksgiving holiday weather, thanksgiving weather, weather, wxLei Zhao

It’s hard to believe now, with air temperatures still hovering around 60 at this hour on Monday, that by Wednesday, our entire region could be looking at accumulating snow! Over the weekend, it has become clear through progressive model runs that the mid-week storm that on Friday looked like it would miss us, is tracking to hit us on Wednesday, leading to a high impact storm just in time for the busiest travel day of the year. We’re talking the whole package: wind, rain, and snow.

Tuesday – we continue to stay in the warm sector of a low pressure system that will be exiting to our northeast through Quebec. Cloud cover will be minimal and we should see temperatures hold around the 60 degree mark.

Wednesday – a complex weather situation develops as a coastal low that forms offshore of the Georgia/Florida border Tuesday makes its way up the Northeast coast. Temperature profiles seem to be pointing towards a mostly snow event (the first big snow storm for the region). With the cold front pushing through late Tuesday, temperatures Wednesday will likely peak in the morning around 40 and start to drop slowly through the day as precipitation moves in across the area, generally from southwest to northeast. Wind will start to pick up, first from the southeast, then east and gradually becoming northeast between 25-35mph.

The tricky part about this forecast is that there is still enough uncertainty in the storm track for there to be some last minute changes. As it currently stands, the center of the strengthening coast low is forecast to move on top of or just west of the 40ºN 70ºW benchmark, a scenario that favors a high-impact nor’easter type event for our region. Winter storm watches are already up over much of the interior Northeast. In these areas, we are looking at anywhere from 4-10″+ (depending on where the heaviest band sets up). Along the coast, under the current forecast track and methodology, it is looking like enough rain mixes in during the day Wednesday to keep snow accumulations from topping 5-6″.

Again the storm track could change, and if the track moves slightly to the east, the heavier snow could hit the city, along with some colder air. Regardless, this does not bode well for people who are doing last-minute traveling for Thanksgiving. I would expect widespread flight delays, while traffic conditions on the road could deteriorate quickly especially later in the day with temperatures dropping and snow beginning to stick.

Thursday – Thanksgiving Day itself looks like it will be OK for the parade, and other activities. The coastal storm will have pulled to our northeast, and any lingering effects should clear up early. Temperatures will be around the 40 degree mark in the city, which means that snow which accumulates will not melt all that quickly.

Friday – will be the coldest day of the holiday stretch, with temperatures only in the mid-30s. Areas of snow that have melted during Thursday could re-freeze.

The remainder of the holiday weekend looks good so far, with no major precipitation anticipated until Sunday/Monday.

NYC Weekend Weather – Nov 20, 2014

November 20, 2014NYC, Outside of NYC, Rain, Storms, Weather Update, Weekendcold front, mid-latitude cyclone, new york city weather, nyc weekend weather, nyc wx, occluded front, thanksgiving nyc weather, thanksgiving weather, warm front, warm sector, weather, weekend weather, wxLei Zhao

We got a break from the arctic chill briefly today, but temperatures will fall again for Friday as a cold front currently sitting on top of us passes through. High pressure builds in Friday allowing for sunny conditions, but temperatures will still not be that warm. A big warm up is in store for the second half of the weekend and we could be hitting a rainy low-mid 60s by Monday.

Friday – following the passage of a cold front sitting over us now, skies will clear up overnight tonight and allow for excellent radiational cooling, so low temperatures will be generally in the upper 20s in the city. High pressure works its way in Friday, but with the influence of a cool west wind, the high temperature will probably still only be near 40.

Saturday – another nice day, with plenty of sun, and temperatures will be slightly warmer in the mid-40s, but the big warm up won’t occur until Sunday.

Sunday – a low pressure center with its origins over the Texas Panhandle will be moving northeast towards our area. A warm front will rotate around in front of it, allowing for the influx of a comparatively very warm and moist airmass into the area. The chance of rain will increase steadily along with cloud cover throughout the day Sunday such that by the late evening, showers will be likely. High temperatures should be in the mid-50s.

gfs_namer_081_1000_850_thick — Significant warm up ahead for the latter half of the weekend going into early next week

Monday – as the forecast map from the Weather Prediction Center below shows, the low pressure system from the map above is forecast to intensify significantly as it pulls northeast. This is a classic, mature mid-latitude cyclone with an occluded low and front (purple line extending from the center of the low), a cold front, and a warm front. The warm front will rotate through first, allowing us to get into the warm sector, where there will be plenty of energy and moisture for rain, which could occur in periods throughout Monday. High temperatures will be balmy in the mid-60s.

Thanksgiving Storm?

The chance of a significant Thanksgiving storm is decreasing, though not completely nil. Once the cold front above passes, we’ll see a return to cooler temperatures in the low 50s. It’s worth mentioning that the set up behind the cold should once again favor lake effect snow, so if you’re traveling to any of the usual snow belt areas around the Great Lakes, be prepared.

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 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 – Aug 25, 2014

August 25, 2014NYC, Rain, Thunderstorms, Weather Update, Weekendlabor day, labor day weekend, nyc weather, nyc wx, rain, weather, wxLei Zhao

We have a fairly straightforward weather week ahead of us leading into the Labor Day Weekend. Currently, our region is sitting under an area of high pressure, which will be sliding to the southeast. As it does so, winds will shift to the south and southwest, allowing the entry of a warm and humid airmass that’s been responsible for brutal triple digit heat in the southern tier of the country.

Tuesday – temperatures will continue to climb into the mid-upper 80s under clear skies due to the aforementioned atmospheric dynamics.

Wednesday – this will be the warmest day of the week with temperatures approaching, if not topping 90, in some spots around the region. Some clouds will start to build in ahead of a cold front that is forecast to push through the area late Wednesday or Thursday. There is some discrepancy between different forecast models as to whether there will be a significant chance for precipitation with this frontal passage. Given this set up, it is likely even if there is rain, it won’t be widespread in coverage or long in duration.Thursday – following the passage of the cold front, temperatures will fall back into the low-mid 80s for Thursday. Mostly sunny skies will return with high pressure moving in behind the cold front.

Friday – should be a similar day in most respects to Thursday, with slightly cooler highs around 80.

Labor Day Weekend – currently, Saturday looks like the best day of the long weekend, with high pressure still in control over the region. High temperatures should be around 80 again with mostly sunny skies. Unfortunately, it does appear that there will be an increasing chance of precipitation in the form of showers and thunderstorms Sunday afternoon and Monday. More on this later in the week.

NYC Weather Update – Aug 18, 2014

August 18, 2014NYC, Rain, Weather Updatenyc weather, nyc wx, weather, weather record, wxLei Zhao

This week will feature mostly calm and tame conditions for the most part, which is excellent news in comparison to last week when a record-breaking storm dropped 13″+ of rain on Islip.

Today-Wednesday will feature essentially the same weather, sunny to mostly clear skies with pleasant high temperatures in the upper 70s and low 80s.

Our first and only real chance at precipitation this week will be on Thursday, and it’s a low chance at that with the passing of a weak impulse of energy through the area.

Friday – high temperatures will continue to drop into the mid-70s as winds coming from the east will allow for a cooler marine air layer to park over the area.

NYC Weather Update – Jul 14, 2014

July 14, 2014Flooding, NYC, Rain, Storms, Thunderstorms, Weather Updateflash flooding, flooding, nyc weather, nyc wx, severe thunderstorms, severe wx, storm prediction center, weather, wxLei Zhao

The Storm Prediction Center has placed the entire NYC metro area in an area for a slight risk of severe weather today. A strong low pressure center over the Great Lakes and its associated cold front are slowly making their way towards the Eastern Seaboard. Despite the cloudiness today, forecasters are still fairly confident that atmospheric conditions will be favorable for the formation of severe thunderstorms in the region. Based on current radar trends, these storms would most likely not be arriving in the NYC area until later this afternoon. The primary threat to our area will be damaging winds and torrential rain capable of triggering flash floods.

Tuesday will feature a similar set up for weather over the region, though there is less risk for severe weather tomorrow. However, strong storms are possible throughout the day and the risk of flash flooding is a distinct possibility. High temperatures will be in the mid 80s despite cloud cover, due to the influence of warm, humid air rushing in between the cold front and high pressure offshore over the Atlantic. This same warm, humid air mass is what will feed the storms for today and tomorrow. As you see below, the forecast rainfall total for today and tomorrow is as high as 3.6″ over Northeastern New Jersey, and ranges between 2.5-3″ for most parts of the Tri-State area.

Wednesday – we get a reprieve from the stormy weather as the cold front and storm system finally move east of NYC. Expect a cloudy start to the day with gradual clearing and conditions improving markedly. The next weather story for Wednesday through the end of the week is the cool, polar air mass that will be a dominant feature. High pressure will build in behind this storm system and usher in much cooler temperatures, with highs in the low 80s Wednesday-Friday, and overnight lows in the low-mid 60s in the city, and in the 50s north and west!

Thursday & Friday – expecting these two days to be essentially the same weather-wise, with high temperatures in the low 80s in the city (and upper 70s further north). Sunny to mostly clear skies for both days.

NYC Weekend Weather – Return of the Polar Vortex? – Jul 11, 2014

July 11, 2014NYC, Outside of NYC, Rain, Weather Update, Weekend500mb analysis, atmosphere, meteorology, new york city, new york weather, nyc, nyc wx, polar vortex, upper air, vortex, weather, weekend weather, wxLei Zhao

You may have heard from media reports that the dreaded polar vortex is set to make a return to the Eastern US during the middle of the coming week. I’ll discuss that in detail below. First, for the weekend forecast:

Today & Saturday – a very pleasant couple of days in the wake of the cold front that finally pushed through our area yesterday. You can feel a marked drop in humidity, and temperatures are much more comfortable. Saturday, high temperatures should top out in the mid 80s in NYC.

Sunday – a chance for afternoon thunderstorms and a high in the mid 80s, chance of rain increasing through out the day into the overnight hours.

Polar Vortex?

Forecast models are in good agreement that beginning Tuesday into most of the rest of next week, an upper air vortex (see below, the trough with an inclosed region surrounded by the blue arrows) will drop into the Midwest and Northeast from the northern regions of Canada. This vortex can be technically referred to as a polar vortex, a term that instantly revives media hype about how cold it will be. But keep in mind, during the summer, polar regions heat up as well, so even the coldest polar airmass and vortexes are much milder than their winter counterparts. Furthermore, the influence of the sun is quite strong as we just passed the summer solstice, so the sun is sitting at a very high angle each day and is highly effective at heating the air quickly. Hence, temperatures are expected to be much below normal for some areas, but we’re not talking about snow or ice.

Screen Shot 2014-07-11 at 1.13.53 PM — Upper air forecast from GFS for Monday, 8PM EDT, 500mb absolute vorticity.

Next Week

There will be a good deal of energy traveling with the polar vortex, so we’re expecting a somewhat disturbed pattern of weather for the beginning of next week. Tuesday & Wednesday will see the best chances for rain and thunderstorms with a cold front approaching us from the west. Before the cold front, we’ll still see temperatures in the mid to upper 80s with a chance for thunderstorms Monday. Once the cold front passes, we’ll be right in the mix with the “polar” air mass, so our high temperatures will drop into the low 80s, and overnight lows will drop into the upper 60s for the latter part of the week.

NYC Afternoon Weather Update – Jul 9, 2014

July 9, 2014NYC, Severe Weather, Thunderstorms, Weather Updatenyc weather, nyc wx, severe weather, severe wx, spc, storm prediction center, thunderstorms, weather, wxLei Zhao

The Storm Prediction Center has again placed western and interior portions of the NYC region under a slight risk for severe weather today. The atmospheric setup this afternoon is similar to yesterday, with plenty of solar heating and humid air leading to moderate instability. At this hour, CAPE values (a measure of instability) are already hitting 1500-2500 J/Kg across the area, with greater instability further south.

There are already a few scattered thunderstorms forming over Eastern Pennsylvania. These storms are not yet hitting severe limits, but conditions are favorable for further development and increase in areal coverage. With winds aloft mostly unidirectional from the southwest, damaging wind gusts would be the primary threat. Storms that form to the southwest of NYC near the Philadelphia metro area and Central New Jersey would be the ones to watch for immediate impacts in the city.

These storms are still several hours away, and it remains to be seen whether they will hold up upon encountering the cooler and stabilizing influence of marine air infiltrating along south-facing shores with the southwest winds and a sea breeze. Last night, the line of severe thunderstorms weakened just before it hit NYC, sparing us from some wicked weather for the night. The same case may unfold again today, but the situation bears monitoring.

LZ | Weather

Weather updates & posts for NYC region