Monthly Archives: June 2015

NYC Weather Update – Jun 30, 2015

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This short holiday week will feature decent weather for the most part, with the exception of Tuesday night into Wednesday morning. As of now, it does appear that there will be a chance of showers/thunderstorms on July 4th itself, however, uncertainty and considerable disparities between different forecast models has been noted by forecasters. We should have a clearer picture of the situation later this week.

Rest of today – clouds gradually increase in coverage during the day today with high temperatures in the low-80s. Overnight, chances for rain will steadily pick up as a warm front approaches the area from the south and west.

Wednesday – a mostly cloudy day with highs in the low-mid 80s. There is a good chance for showers early on in the day. However, the chance of rain starts to diminish in the afternoon, and it is unclear if there will be enough instability remaining in the atmosphere following the passage of the warm front above to support more rain or storms.gfs_namer_033_1000_850_thick

Thursday – a cold front following on the heels of the warm front mentioned above will mean that there is still a chance for showers and thunderstorms as that frontal boundary approaches. Temperatures should be similar to Wednesday, in the low-mid 80s.

Looking ahead at the holiday weekend, it looks like both Friday and Sunday should be mostly sunny with temperatures in the low-80s. There is a small chance for rain and thunderstorms for Independence Day, but there is enough forecast uncertainty in the forecast models to hope for a dry day Saturday as well.

NYC Weekend Weather | Jun 25, 2015

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The first half of this first full week of the summer felt very much like mid-summer, with hot, humid conditions and even some severe thunderstorms. The second half of this week, along with the weekend will feel a lot more like late spring, with Saturday afternoon into Sunday morning shaping up to be a washout.

Rest of today – pleasant, sunny skies, with a wind from the northwest, will yield comfortable high temperatures in the mid-80s.

Friday – an area of low pressure will be tracking eastward from the Midwest along a nearly stationary frontal boundary that will be positioned over southern New Jersey. The timing of this wave of low pressure will be overnight Thursday into Friday morning. Rain should end by noon Friday. With mostly cloudy skies, high temperatures will only top out in the mid-70s.

North American Model high resolution simulated radar image for Friday at 8AM EDT
North American Model high resolution simulated radar image for Friday at 8AM EDT

Saturday – the respite from the rain will be short-lived. Saturday morning into the early afternoon should remain rain-free, though temperatures will again be suppressed in the low-mid 70s. Another, more potent area of low pressure will make its approach from the west during the day Saturday. The precipitation shield associated with this low should begin to fill in over the area beginning in the mid-afternoon hours. Periods of showers will continue falling, with moderate to heavy rain at times, throughout the remainder of the day and overnight Saturday.

North American Model high resolution simulated radar for Saturday at 2PM EDT
North American Model high resolution simulated radar for Saturday at 2PM EDT

Sunday – rain begins to taper off on Sunday from south to north as the center of the low pressure responsible for this storm moves to our northeast. Rain should end in the early afternoon hours. Mostly cloudy skies are expected with temperatures in the mid-70s. Rain from last week has put a dent in drought conditions across New York state, but areas of Central upstate New York and eastern Long Island could still use this rain. The downside is that it will put a damper on many outdoor plans for the first full weekend of the summer, and the first weekend after school ends here.

Monday – conditions improve on Monday as the low pressure continues to pull away. High temperatures should remain in the mid-70s with cloud cover decreasingly steadily.

 

NYC Weather Update – Jun 22, 2015

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The official start of summer was this weekend, and this week will be accompanied by decidedly summer-like weather. High temperatures for the first half of the week will be quite warm, in the mid-upper 80s, with some areas probably passing the 90º mark on Tuesday. Along with the summer-like temperatures, there will also be a chance for strong thunderstorms.

Rest of today – sunny skies will allow temperatures to rise up into the upper-80s and possibly 90 in the city. However, since humidity and dewpoints are low, it will not feel oppressively hot.

Tuesday – a cold front approaching from the west could serve as the trigger for some strong to potentially severe thunderstorms. Ahead of this cold front, continued southwesterly winds will maintain very warm temperatures in the upper-80s to low-90s in some parts. noaad2

Timing of thunderstorms looks to be in the late afternoon, possibly around the PM rush, with a line of storms moving . Warm temperatures and a humid airmass look to yield moderate SBCAPE (surface-based convective available potential energy) values in the 2000-3000 J/Kg range. This environment should support intensification for any storms that form to marginally severe limits. Correspondingly, the Storm Prediction Center has placed most of the area in a slight risk area for severe weather tomorrow, except for eastern Long Island and Connecticut.

North American model high resolution simulated radar for Tuesday, 5PM EDT
North American model high resolution simulated radar for Tuesday, 5PM EDT

Wednesday – behind the cold front, things dry out and temperatures should cool off a bit, with high temperatures in the mid-80s.

Thursday – this will begin a period of unsettled weather that looks poised to persist through the weekend. The front that moves south of us Wednesday then stalls not too far, and remains nearly stationary starting Thursday. Several waves of low pressure are expected to move along this frontal boundary. While at this time, Thursday looks dry, cloud cover will be increasing and temperatures should be cooler, only around 80.

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.