Category Archives: Thunderstorms

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.

gfs_namer_057_1000_850_thick

 

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 Weather Update – May 31, 2015

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We start the week off with some much needed rain and a noticeable cool down in temperatures. Scattered thunderstorms increase in coverage later today and transition into more widespread showers that are expected to persist into the overnight hours. The start of the week will be rainy, cloudy, and cool under the influence of a Canadian maritime airmass. By midweek, we get back into more fair conditions with the sun returning and temperatures back in the mid-70s.

Rest of today – the Storm Prediction Center has placed areas of Northeastern New Jersey in a slight risk area for severe thunderstorms later. Based on latest radar trends and the High Resolution Rapid Refresh model’s output, it would appear that thunderstorms are likely to develop over portions of New Jersey highlighted in the slight risk area, then track eastwards into the NYC metro area later this afternoon into the early evening hours. With breaks in the clouds for sun, we’ll hit temperatures in the low-80s, which when coupled with ample moisture, should support thunderstorms with the potential for heavy rain.

day1otlk_1300

 

High Resolution Rapid Refresh model output for 8PM EST
High Resolution Rapid Refresh model output for 8PM EST

Monday – all the activity occurring today and going into the overnight hours is associated with a cold front that is moving south into our area. As this cold front pushes through, east-northeast winds will set up, allowing a cooler, Canadian maritime airmass in. This will translate into cooler than average temperatures only in the mid-60s with showers likely throughout the day.

Tuesday – wet, cool weather continues Tuesday with highs again only in the mid-60s and the ongoing chance for rain showers throughout the day. This extended period of rain from later today into Tuesday should bring some relief to the moderate drought conditions over parts of the Northeast, with the potential for as much as 4″ of rain over the period in certain parts of the region.

Possible total rainfall over the next 48 hours
Possible total rainfall over the next 48 hours

Wednesday – high pressure finally builds back in Wednesday, pushing away the rainy weather, and yielding pleasant temperatures in the low-mid 70s under partly cloudy skies.

Thursday – slightly warmer than Wednesday, with highs in the upper-70s in NYC.

NYC Weather Update – May 26, 2015

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It certainly does feel as though Memorial Day 2015 has been the unofficial start of summer, given the warm and humid temperatures we’ve had from Sunday onwards. The warm, late-June like temperature trend continues through mid-week, with some chance for thunderstorms. Rain in any form would be most welcome, given that the region has been placed in a region of moderate drought as of this week.

Rest of today – the Bermuda high, more typical of mid-summer, brings us very warm and humid high temperatures in the mid-upper 80s, more than 15ºF above average for this time of year. If you like the heat, go out and enjoy it because we might see showers and thunderstorms both Wednesday and Thursday afternoons.

Wednesday – a weak cold front approaches from the west, bringing with it a chance for showers and thunderstorms. The critical question for NYC will be how long organized storms can stay together as they enter into influence of cooler, maritime air nearer to the coast. Temperatures will remain warm in the low-mid 80s with clouds and some breaks of sun. As is generally the case in these setups, the more sun we can get in the afternoon ahead of the frontal bou

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North American Model high resolution simulated radar image for 8PM EST Wednesday

Thursday – we get another shot at thunderstorms Thursday afternoon and evening, with highs likely topping out around 80 under mostly cloudy skies.

 

Moderate Drought for the Region Forecast to Persist

We’ve had an remarkable run of sunny, rain-free days, and above average temperatures for much of May (and indeed even going back a couple of months), and while that’s translated to pleasant weather for outdoor activities, it also has meant that we’ve entered into a stretch of moderate drought. We had a stretch of no rain for 23 consecutive days, earlier this month, which definitely didn’t help things. According to the USDA Drought Monitor, Central Park recorded 7.12″ of rain from March 1st through May 19th, which is only about 63% of average for this time of year.

20150519_northeast_trd

 

While we are only in the lowest tier of drought and were just added to this category this week, these drought conditions bear watching. We hope to get some rain out of this week, and it looks like more storms are on the way this weekend, however, the drought forecast for our region looks to have the drought persist through this summer.

season_drought

NYC Weather Update – May 18, 2015

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This week starts off with a backdoor front over us, bringing us much cooler temperatures than yesterday, as well as patchy dense fog. Tomorrow, the Canadian maritime airmass responsible for these conditions will be replaced by a warm, moist airmass originating from the Gulf. By mid-week, a passing cold front will usher in seasonable, and dry conditions to the region.

Rest of today – mostly cloudy, cool, with an easterly wind suppressing temperatures, which will top off in the mid-60s.

90fwbg

 

Tuesday – the backdoor front above will move back north overnight as a warm front. This will allow a transition to a southwesterly flow, which will bring warm, Gulf air into the area. High temperatures should be in the mid-70s amidst cloudy skies, punctuated by periods of rain as a cold front approaches from the west. There is some chance at a couple thunderstorms as well.

96fwbgus_init_2015051800

Wednesday – when the cold front moves through late Tuesday, it will set up cooler, but pleasant, dry, and sunny conditions on Wednesday. High temperatures around 70.

Thursday – the good weather continues with mostly sunny skies and high temperatures in the low-70s.

NYC Weekend Weather (Brooklyn Half Marathon) – May 14, 2015

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This week ends off with pleasant, sunny, dry weather, and temperatures slightly above average in the low 70s. We get a chance at some much needed rain (there were actually brush fires yesterday, giving you an idea how dry it’s been), but the unfortunate part is that the rain will likely occur in periods on Saturday. Sunday will be better, as it doesn’t look like the rain sticks around that long.

Rest of today – a gorgeous spring day with high pressure in control, yielding a cloud-free and seasonable day with highs in the low 70s.

High pressure firmly entrenched over us today and tomorrow.
High pressure firmly entrenched over the region today and tomorrow.

Friday – expecting more of the same during the day, mostly sunny and mild with temperatures topping out again in the low 70s. Later Friday night, there could be a few showers and thunderstorms that develop as an approaching frontal system nears the area.

Saturday – lingering showers and maybe a thunderstorm or two in the morning, but it does not appear the entire day will be a washout. We’ll be in the warm sector which should allow for temperatures to approach 80 or slightly higher, depending on the cloud cover situation in the afternoon hours. Sadly, I know this is not what all you runners that are going to be doing the Brooklyn Half Marathon want to hear.

North American Model high resolution output for Saturday at 11AM, showing the possibility of showers.
North American Model high resolution output for Saturday at 11AM, showing the possibility of showers.

Sunday – at this point, it appears Sunday will be dry, with more clouds than sun, and temperatures remaining warm in the upper-70s. A blocking high pressure center over the Gulf of Maine should be enough to prevent rain from entering the area. gfs_namer_108_1000_850_thick

Monday – the high pressure depicted above will retreat eastward a bit, which would allow for a better chance of rain later Monday evening/night into Tuesday. During the day, conditions should be dry with partly sunny skies and a high near 70.