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NYC Weather Update

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The weather story for the first part of this week will be a prolonged heavy rain event occurring Tuesday, delivering parts of the region some much needed precipitation. Temperatures will remain slightly below normal through Thursday, first because of the rain and clouds and then due to the influence of high pressure to our west.

Rest of today – NYC remains under mostly sunny skies, however, cloud cover is building to our west, so we could end up with more clouds later this afternoon. It will be a noticeably more humid day, although temperatures will still only top out in the low-80s.

Tuesday – rain should begin falling in the early overnight hours, and looks to persist through the morning and into the early afternoon hours. The heaviest rain seems likely to fall during the morning hours. Thunderstorms cannot be ruled out, and while the atmospheric conditions will not be very favorable (timing of the strongest lift will occur early in the day before any substantial daytime heating, which will be diminished due to cloud cover anyway), a few strong storms could still pop up in the morning. Some areas could see some isolated flash flooding if storm cells end up training over the same spots. Under the cloud cover and rain, high temperatures should be limited again to the low-80s.

North American Model High Resolution simulated radar for 11AM EDT Tuesday
North American Model High Resolution simulated radar for 11AM EDT Tuesday

Wednesday – rain will have cleared out after the passage of the cold front responsible for Tuesday’s storms. Behind this cold front, high pressure will set up over the Ohio Valley, bringing in cool, dry air. Temperatures will be quite comfortable in the low-mid 80s with low humidity.

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Thursday – the pattern of cool, dry weather continues with another day of sunny skies and high temperatures slightly below normal in the low-80s.

Drought Relief

A slight/moderate drought continues to cling to areas of Long Island and costal Connecticut, as you can see from the map below. It does appear that this upcoming Tuesday storm will bring some much needed rain to these particular areas. As you’ll also note from the map of forecast precipitation totals for Tuesday, some of the highest totals are expected precisely in the areas that need them the most.

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Weather Prediction Center's Quantitative Precipitation Forecast for total precipitation between 8AM EDT Tuesday and 8AM EDT Wednesday
Weather Prediction Center’s Quantitative Precipitation Forecast for total precipitation between 8AM EDT Tuesday and 8AM EDT Wednesday

NYC Weather Update – Jul 27, 2015

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The heat will be the main weather story of this week, with temperatures of 90ºF or higher forecast to occur for a majority of the week. This heat does not appear to abate until at least this weekend. Incidentally, according to the Chinese lunar calendar, we’ve just hit 大暑 (literally “big heat”), a period of 2 weeks that are supposed to be the hottest of the summer. Fans of the heat, it is time for you to rejoice.

Rest of today – clouds this morning should slowly give way to more sun in the afternoon. The cloud cover now will help keep temperatures in the mid-80s.

Tuesday – a chance of showers and thunderstorms in the morning, but otherwise hot with highs in the low-90s and a good amount of sunshine.

Wednesday – shaping up to be the hottest day of the week, with high temperatures in the mid-90s.

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Thursday – with a cold front approaching from the west, there may be a few thunderstorms in the afternoon on Thursday which might grant some reprieve from the heat. Otherwise, sun and clouds with a high temperature in the low-90s.

NYC Weekend Weather – Jul 23, 2015

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The end of this week and weekend will be characterized by comfortable conditions and seasonably warm temperatures. A cold front from Canada will be approaching from the west by Sunday, however, this frontal boundary looks to weaken as it nears the area. There should be a small chance for showers and thunderstorms, but it is likely most areas stay dry through the weekend.

Rest of today – high pressure over the Ohio Valley will yield sunny skies, with a high in the mid-80s. Dry air moving from the west will make for a pleasant feel today.

Friday – high pressure remains in control tomorrow, providing for conditions almost identical to today, with highs again in the mid-80s under sunny skies with low humidity.

Saturday – although the high pressure center will weaken somewhat as it moves east on Saturday, it will still dominate our sensible weather, leading to yet another day of basically the same weather conditions with highs in the mid-80s and plenty of sun.

Sunday – with the high continuing to weaken and move to the southeast, we get a chance for some afternoon showers and thunderstorms associated with a frontal boundary originating in Canada moving into the region. Rain chances aren’t all that high, though, so it’s likely most areas stay dry. Highs again in the mid-80s with increasing cloud cover.

Global Forecast System model output for Sunday at 11AM EDT
Global Forecast System model output for Sunday at 11AM EDT

Drought Update

Drought conditions over New York state have drastically abated since the beginning of the month, especially in upstate regions. However, moderate drought persists over parts of Long Island.

Drought index for New York State, areas in yellow indicate slight drought, while areas shaded in tan indicate moderate drought.
Drought index for New York State, areas in yellow indicate slight drought, while areas shaded in tan indicate moderate drought.

NYC Weather Update – Jul 13, 2015

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This week will feature two contrasting airmasses, with the beginning of the week influenced by a warm, humid airmass, before a cold front Wednesday brings some relief from the heat and humidity and brings in cooler, drier air. A warm front, then this cold front, along with the warm temperatures and humidity will lead to the chance for showers and thunderstorms through Wednesday.

Rest of today – warm, humid, with hazy skies and a high in the mid-upper 80s.

Tuesday – a warm front approaches the area from the southwest then stalls to our south. Winds shift to the southeast, providing somewhat of a cooling effect with a sea breeze. However, inland areas should still see temperatures well into the mid-80s. A wave of low pressure will be sliding east along the stalled frontal boundary during the day Tuesday, however, the best chances for rain and thunderstorms associated with this wave look to be confined to areas well west of NYC. A spotty shower or thunderstorm cannot be ruled out in the city.

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Wednesday – as the stationary front from Tuesday moves away, a cold front will be pushing through the region on Wednesday. This will allow for the chance of rain and thunderstorms to persist. Chances for precipitation Wednesday are overall lower than Tuesday, and it will be a set up where most of the area stays dry, with only a few locations picking up appreciable rainfall from a passing storm. Highs will continue to be warm in the mid-upper 80s ahead of the cold front passing through.

Thursday – following the passage of the cold front, high pressure will build over the region. Clockwise flow around this high pressure will usher in refreshing, drier air with a north wind. Temperatures on Thursday will be cooler, in the low-80s.

NYC Weekend Weather – Jun 19, 2015

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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 Sunday
Quantitative Precipitation Forecast for Sunday
North American Model high resolution output for Sunday at 11AM EDT
North American Model high resolution output for Sunday at 11AM EDT 
Drought coverage in New York as of this week
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.

NYC Weather Update & TS Bill – Jun 16, 2015

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We’ve certainly seen plenty of rain during the month of June, yet the NYC region remains in an area of moderate drought as of last Thursday. However, this does not reflect the rain that fell overnight Sunday into Monday. After a gloomy start to the week, we get a break of decent weather tomorrow, before another possible round of rain Thursday. The week ends with some drying out and improving conditions.

Rest of today – highs should top out in the upper-70s to around 80 today, with the potential for showers and thunderstorms later this afternoon. Storms have already formed to our west over northeastern Pennsylvania, but there is a stabilizing marine air layer over NYC and points east, so these storms may yet break apart before reaching us.

 

High Resolution Rapid Refresh model simulated radar for 1PM today.
High Resolution Rapid Refresh model simulated radar for 1PM today.

Wednesday – skies will clear rapidly overnight and lead to a sunny, dry, and pleasant day on Wednesday. Highs should be near 80. The high pressure creating these pleasant conditions will not stay around long, as another warm front approaches from the west.

Thursday – will look a lot like today, with mostly cloudy skies, and a potential for showers and thunderstorms in the afternoon as a warm front nears the region. Highs will be a bit cooler in the mid-70s with the influence of clouds and a southeasterly flow off the ocean ahead of the warm front.

Friday – the warm front from Thursday is followed quickly by a cold front passing Friday morning. Behind this, high pressure takes control and brings decent weather for the first half of the weekend. Highs Friday should be in the low-80s with clouds and sun.

 

Tropical Storm Bill

Over the weekend, a disturbance organized over the western Gulf of Mexico, and by last night it had consolidated and intensified enough to be designated the 2015 Atlantic Hurricane Season’s second named tropical cyclone – Tropical Storm Bill. Bill will be making landfall imminently in Texas as a moderate strength tropical storm with maximum sustained winds of 60mph.

Satellite image of Tropical Storm Bill about to make landfall on the central Texas Gulf Coast
Satellite image of Tropical Storm Bill about to make landfall on the central Texas Gulf Coast

However, for people living in the path of Bill, it is not the wind but rather the potential for dangerous flash flooding that is the primary concern with this storm. Bill is forecast to bring as much as 10″ of rain over the next few days to parts of Texas, and upwards of 6″ for a wide swath of Oklahoma and Missouri. As you may recall, some of these areas were the scene of deadly flooding just a few weeks back, and the arrival of a rainmaker like Bill is most unwelcome for these areas that are still in the midst of recovering. Moisture from Bill will eventually work its way into our region, but in a much less intense way.

Forecast rainfall totals for TS Bill
Forecast rainfall totals for TS Bill

NYC Weekend Weather – Jun 11, 2015

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We will likely be experiencing one of the hottest days of the year so far, with temperatures expected to top out in the upper-80s and into the low-90s in a few spots this afternoon. The warm weather continues through Saturday, when an area of high pressure over eastern Canada brings us some relief from the heat. In terms of the weekend, Sunday will definitely be the better day, with cooler temperatures, but dry weather.

Rest of today – temperatures are expected to top out right around 90 in the city. Increasingly humid air will lead to an uncomfortable feeling day. There is some potential for thunderstorms, some possibly marginally severe, occurring in the afternoon hours as a cold front approaches from the north and west. The orientation of the frontal boundary and primary storm vector will align in such a way that training of storms could occur, leading to the same locations getting hit by multiple storm cells.

In addition, an air quality alert is active today, with PM2.5 particle being the primary driver in pushing the Air Quality Index into the low 100s (unhealthy for sensitive groups).

High Resolution Rapid Refresh model simulated radar composite for 4PM EDT.
High Resolution Rapid Refresh model simulated radar composite for 4PM EDT.
Air quality forecast for today
Air quality forecast for today

Friday – the cold front that pushes through today with some possible thunderstorms will stall just south of the area, then push back north through the area as a warm front Friday. This means we will not get any respite from the heat, with highs again expected to be in the upper-80s to near 90, and another chance at more thunderstorms. There will be more sun Friday than today, but atmospheric dynamics are not expected to be supportive of severe weather.

Saturday – the warm front that passes through Friday comes back yet again as a cold front as it gets dragged along by the low pressure center moving to the northeast. This means yet another chance for thunderstorms, and ahead of that, warm temperatures remaining in the upper-80s.

Sunday – the weather finally settles down and stabilizes as a high pressure center builds to the north in behind the cold front passing on Saturday. This should lead to cooler temperatures and sunny skies for Sunday, when temperatures are expected to be in the low-80s.

 

 

 

 

 

 

 

 

 

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Monday – another frontal boundary will be making its approach from the west on Monday, however, the timing of its approach is such that chances for rain will be low on Monday. Temperatures should again be comfortable around 80.

NYC Weather Update – Jun 8, 2015

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The weekend offered us some respite from what had been a cool, wet week. This week starts off with the potential for more drenching rain and thunderstorms before conditions calm. By the second half of the week, we will experience a noticeable increase in temperatures, with highs on Thursday possibly touching 90 in a few spots.

Rest of today – cloud cover should clear out for the next few hours until the next chance at rain comes later this evening. Depending on how much sun we get, high temperatures could reach the mid-upper 70s. Later this evening and overnight, we should see some showers in advance of an approaching cold front. While thunderstorms are expected west of the Hudson, the stabilizing influence of onshore sea breeze bringing in a marine air layer will serve to limit thunderstorms from persisting across NYC and points east along the coast. In any case, the heaviest rain appears to hold off until after 8PM.

 

High Resolution Rapid Refresh model output for 1AM EDT Tuesday.
High Resolution Rapid Refresh model output for 1AM EDT Tuesday.

Tuesday – mostly cloudy day with highs near 80. The aforementioned cold front draws nearer, giving us more chances at showers and thunderstorms, particularly later in the day. As with today, stronger storms will likely be limited to inland areas to the north and west that will not be affected by a sea breeze.

Wednesday – weak high pressure builds in for Wednesday behind the cold front. Generally sunny skies with highs in the mid-80s.

Thursday – humid and warm air flowing in from the southwest ahead of another frontal system will raise temperatures on Thursday to near 90ºF. This will feel like a late-July summer day with the high humidity.

NYC Weekend Weather – Jun 4, 2015

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We have struggled to reach normal temperatures this week, with plenty of rain and Wednesday as the only sunny break. We end this week with more cool, damp weather, before transitioning to warmer, drier conditions this weekend. Portions of the area received anywhere between 2-4″ of rain between Sunday night and Tuesday night, which will help improve drought conditions, however, these rainfall totals also led to flash flooding across large portions of the area.

Rest of today – cloudy, with a small chance for isolated light showers, cool with temperatures topping out only in the low-mid 60s, about 10ºF below normal for this time of year.

Atmospheric setup favoring the cool, cloudy, damp weather
Atmospheric setup favoring the cool, cloudy, damp weather

Friday – more clouds and cool weather, with this easterly onshore flow regime sticking around for one more day. High temperatures will again be only in the mid-60s, much below normal. There is a slightly higher chance Friday for scattered showers, but nothing like the soaking we got earlier this week.

Saturday – some improvement in conditions will take place Saturday as high pressure starts building from the west. Partly sunny skies may give way to more sun, with high temperatures warmer near 80.

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Sunday – high pressure moves to our east, allowing us to enjoy another pleasant, dry day, with high temperatures in the mid-70s.

Monday – a frontal system approaches the area. Ahead of the front, warmer air will flow in from the southwest, giving us temperatures at or above normal near 80ºF. As the front nears, thunderstorms and showers are possible across the region.

 

Arctic Jet Stream Slowing Leading to Increased Incidence and Duration of Extreme Weather? 

The massive quantities of snow that fell over the Northeast this past winter, the flooding rains over Texas last month, the enduring drought over California, and the asphalt-melting heatwave in India have all raised the question of what is causing this apparently increased incidence of long-duration extreme weather events. One possible explanation offered by researchers at Rutgers University is that the polar jet stream circling the Arctic has been slowing.

Jet streams are generated by two factors: the rotational energy of the Earth spinning on its axis, and the pressure gradient between two airmasses of varying temperatures. In the case of the polar jet circling the Arctic, rapid warming of the Arctic over the last couple decades has led to a decreased thermal and pressure gradient between air over the Arctic and air directly to the south. Researchers posit that this effect has led to a slowing of the polar jet stream. Since the jet stream is responsible for moving large (synoptic) scale weather patterns, any affect on its speed and orientation can have dramatic impacts for widespread regions of the world. In this case, the slowing polar jet stream is theorized as the mechanism behind the prolonged effects of the weather events mentioned above.

NYC Memorial Day Weekend Weather – May 21, 2015

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We’ve had a cloudier, cooler middle stretch of the week than expected, however, the payoff will be a splendid Memorial Day weekend. All three days of the long weekend look to be suitable for outdoor activity, with Sunday probably being the best day with warm highs in the mid-70s. There could be a chance of thunderstorms late Monday, and this will bear monitoring.

Rest of today – mostly cloudy today due to the influence of a low pressure system to the south, which will be moving out over the Atlantic today. There could be a few showers associated with this coastal low, but these would be primarily confined to NYC and Long Island. Otherwise, northeast winds associated with the low along with clouds overhead will act to suppress high temperatures in the low-60s.gfs_namer_024_1000_850_thick

 

Friday – showers are possible overnight from today into Friday morning, then clouds should clear in the morning, although they may reappear for later in the afternoon. Still, it will be a considerably sunnier and warmer day with high temperatures in the mid-70s.

Saturday – high pressure builds to our west giving us sunny skies, with the tradeoff being cooler temperatures and winds coming in from the north and northwest. Highs should top out in the mid-60s.

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Sunday – once the high above shifts to the east, clockwise flow around it will turn to the south and southwest, meaning we will get much warmer air coming into the region. High temperatures should be able to climb into the mid-upper 70s, especially if cloud cover is minimized.

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Memorial Day Monday – it looks as though a warm front will be trying to push its way through the area on Monday, so there may be some chance of thunderstorms or showers along this frontal boundary, but it’s not easy to pinpoint how wide the coverage of these would be, or what the duration is at this point. Outside of this chance for some precipitation, the rest of Monday should be pleasant with highs again in the mid-70s, albeit with more cloud cover than Sunday.