Category Archives: Thunderstorms

NYC Weather Update – Labor Day Weekend

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Rejoice! The long awaited Labor Day Weekend is upon us. Although I’d love to say that the weather will be fantastic throughout, but unfortunately there will be a few disturbances traversing the region the second half of this weekend. Thunderstorms accompanying these disturbances may literally rain on the annual West Indian Day Parade in Brooklyn on Monday.

Friday – the remainder of today will be a picture perfect, fall-like day with high temperatures hovering right around 80. A pleasant, dry airmass is in place in association with an area of high pressure that’s currently sitting over us.

Saturday – essentially a repeat of Friday, but with a bit more cloud cover.

Sunday – high temperatures on Sunday will be considerably warmer than Saturday, since the area of high pressure sitting over us now will have moved to the east, building up southwesterly winds and allowing for an influx warm air to penetrate the region. Expect more humid and warm highs between the mid-upper 80s. A weak frontal boundary will be approaching Sunday, and transit the region late Sunday into Monday. This will be our first shot at rain and thunderstorms, some of which may deliver some heavy rain.

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Labor Day – the timing of the aforementioned frontal passage will be critical in terms of sensible weather Monday. It currently looks like Monday will be partly cloudy, with highs again in the mid-80s. There will be an increasing chance of scattered thunderstorms later in the day Monday leading into Tuesday as another weakening cold front nears the area.

Tuesday – the return to the work week will continue to feature warm and humid highs in the mid-upper 80s and a continued chance of thunderstorms as that cold front works its way through.

NYC Weather Update – Aug 25, 2014

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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.Screen Shot 2014-08-25 at 6.18.10 PMThursday – 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 – Jul 21, 2014

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This will be my last weather update for the next 3 weeks as I will be traveling to Costa Rica during that time.

Tuesday – things will heat up on Tuesday as the high pressure center responsible for the what has been a refreshingly cool and fair stretch of weather moves to the southeast. This will allow warm, tropical air to move back into the area, setting the stage for high temperatures to climb well into the mid-upper 80s under partly cloudy skies.

Wednesday – the hot weather will intensify Wednesday as temperatures near or top 90 with a noticeable increase in humidity as well. Warm, humid air will be sandwiched between the Bermuda high and an approaching cold front. Scattered showers and thunderstorms are possible later in the day Wednesday. Inland areas to the west of NYC are most likely to see precipitation Wednesday.

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Thursday – the aforementioned cold front will move further east, giving the city itself its best chance of a soaking rain on Thursday. Given the humidity and amount of water available for storms Thursday, flash flooding is possible within the heaviest downpours, otherwise mostly cloudy with temperatures in the mid 80s. I wouldn’t be surprised if a few strong to severe thunderstorms popped up Thursday.

Friday – the cold front will clear our area and exit to the east, while cooler air filters down from Canada. High temperatures will return to the low 80s with mostly clear skies.

The Weekend – looks like the weekend itself will be another nice one, with high temperatures in the low 80s both Saturday and Sunday. There is a chance of showers and thunderstorms Sunday leading into what appears to be a fairly active weather pattern for the beginning of next week.

 

NYC Weather Update – Jul 15, 2014

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A correction from yesterday – I had said today may see less potential for severe weather. In fact, the Storm Prediction Center once again has most of the NYC metro area under a slight risk for severe thunderstorms later today.

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Based on current satellite trends, it does appear there will be some breaks in the clouds this morning and afternoon. This will allow sufficient sunshine and daytime warming to fuel strong to severe storms across our region again later today. In the upper atmosphere, largely unidirectional winds from the south-southwest, a favorable jet stream set up, and approaching cold front suggest the potential for storms with damaging wind gusts and even some hail. Flash flooding is again a distinct possibility.

As you see below, portions of our area saw up to 1-1.5″ rain yesterday, and these same areas are in the target zone for severe storms today as well. With the upper level winds lining up from the south-southwest, training (where multiple storms hit the same location over a period of time) of storms is likely. This will enhance the risk for flash flooding.

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A note about the term unidirectional winds: Unlike a hurricane, severe thunderstorms thrive on upper atmospheric energy, and unidirectional winds at all levels are more conducive to imparting a rotation on a rising parcel of air (rotating thunderstorms can produce tornadoes).

Otherwise, expecting a warm, humid day, with highs in the mid 80s and some sun before storms arrive later in the afternoon. It will be cooler and more comfortable tomorrow with this stormy cold front having passed us!

NYC Weather Update – Jul 14, 2014

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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.
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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.Untitled2

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 Afternoon Weather Update – Jul 9, 2014

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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.

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NYC Nowcast – Strong to Severe Thunderstorms Approaching

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Severe thunderstorms are approaching the area from our west. Several distinct bowing segments of severe thunderstorms have been making their way steadily towards our area from Central Pennsylvania since earlier this afternoon.

These storms have a history of producing damaging wind gusts and even a few tornadoes. Sundown over some of the areas under the current Severe Thunderstorm Watch areas in our region may weaken these storms, however, overall atmospheric conditions are quite favorable to the forward propagation of this line.
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NYC Weather Update – Jul 8, 2014

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We had a nice couple days of seasonable, dry, and sunny weather this past weekend in the wake of Hurricane Arthur’s passage, but that came to an end yesterday and today. The high pressure that gave us the nice conditions moved to the southeast and out over the open waters of the Atlantic, merging with the semi-stationary Bermuda high. As you may know, this set up favors hot, humid temperatures all along the east coast, and we are no exception. Expect high temperatures to top out in the low-mid 90s today, with uncomfortably high humidity.

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Wednesday – we may get some relief from the heat later today and overnight with a pre-frontal trough and scattered diurnal thunderstorms forming in the hot, unstable air. However, tomorrow will be more or less a repeat of today, with temperatures in the upper 80s to low 90s and muggy conditions.

Thursday – The cold front above won’t actually reach us until late in the day Wednesday, but when it does hit us Thursday, it will bring some chance for scattered thunderstorms and a slight drop in temperatures back down into the mid 80s.

Friday – amazingly, our streak of great weekend weather (with the exception of Arthur) is set to continue. Once the cold front clears us Thursday, we’ll see high pressure build in from the west Friday, which means some cooler winds and lower humidity airmass from Canada moving in. Temperatures should be milder, in the low-mid 80s Friday through the weekend.

Our next shot at precipitation will be late Sunday into the beginning of next week.

NYC Weather – Independence Day – Jun 30, 2014

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Lots to talk about on the last day of June, which brings with it the opening of a warm trend and possible mini heat wave. A stubborn low pressure system over the Plains States is pushing warm and humid air from the Gulf ahead of a leading cold front. As a result, Tuesday will feature warm, muggy conditions with highs in the upper 80s, maybe even touching 90.

Wednesday, that frontal boundary comes closer, and with the heat and humidity in place, we’ll have the right conditions for some pop-up showers and thunderstorms later in the day. However, coverage is expected to be widely scattered. Highs again will be in the upper 80s, possibly hitting 90.

Thursday -as the cold front makes its approach in earnest, a pre-frontal trough is forecast to develop, and this should help spark off more widespread showers and thunderstorms than on Wednesday. Expect high temperatures to be somewhat lower due to cloudy skies, but still warm and humid in the mid to upper 80s.

Friday (Independence Day) – A lot of weather forecasters were saying earlier this weekend that July 4th was going to be a nice day with no rain. Sadly, that doesn’t appear to be the case now, as the timing of that pesky cold front has slowed down somewhat. This does mean you could see rain and or thunderstorms during the day Friday and into Friday night, but at least the heat will break somewhat with temperatures only around 80.

Cold front right on top of us Friday could rain on your July 4th plans.
Cold front right on top of us Friday could rain on your July 4th plans.

First Named Tropical System of the Atlantic Hurricane Season?

Over the weekend, a disturbance off the east coast of Florida began to show signs of increasing organization, to the point that the National Hurricane Center now gives the system an 80% chance of forming into a tropical depression in the next 2 days. If it does, then it will become the first named tropical system of the 2014 Atlantic Hurricane Season.

High resolution satellite image of the incipient tropical system off the east coast of Florida
High resolution satellite image of the incipient tropical system off the east coast of Florida

Why does this matter to us? Well, as it currently stands, it appears this tropical system/possible storm may impact our weekend weather here in the Northeast. Some forecast models have this storm moving to the near offshore waters of the Northeast by Saturday (indicated in pink circle below). This could bring the potential for rain to parts of the Northeast, in particular, New England. Fortunately, it doesn’t appear as though this storm will strengthen much (below you see the lowest pressure at the center of 1012mb, for reference, normal pressure at sea level is 1013mb), and in fact, it will likely make a transition to becoming an extratropical cyclone/storm rather quickly after it moves north of Florida. Still, it’s a bit too early to tell just where this storm will go, so it bears monitoring.

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Possible storm tracks as illustrated by GFS ensemble members
Possible storm tracks as illustrated by several different forecast models

NYC Weather Update – Jun 25, 2014

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A warm and humid day out there in the Tri-State this afternoon. You can feel it’s potential thunderstorm weather. In fact, the Storm Prediction Center has issued a mesoscale discussion (analysis of weather conditions conducive to severe weather on a medium scale – 10km-500km). Very moist air, warm temperatures, combined with a slowly approaching cold front set the stage this afternoon for possible development of strong to marginally severe thunderstorms. This is especially the case over inland areas, as depicted below. In general, expect a line of showers and maybe a couple thunderstorms to pass through the area later this evening into the overnight areas when the cold front finally pushes through.

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Storm Prediction Center Mesoscale Discussion http://www.spc.noaa.gov/products/md/md1147.html

Thursday – there could be some lingering showers in the AM, but things will dry out quickly and clouds will slowly give way to sunnier skies. High temperatures will be a bit cooler than today, in the upper 70s to low 80s.

Friday – a splendid end to the work week with mostly sunny skies and comfortable, less humid conditions and temperatures in the low 80s.

Canadian high pressure will move slowly to our east, ushering in some warm air and calm skies
Canadian high pressure will move slowly to our east, ushering in some warm air and calm skies

Saturday and Sunday will both again feature excellent weather as a high pressure system works its way over our region following this cold front. As the high pressure slowly slides to the southeast, it will bring us southerly winds that will usher in another period of warm and humid weather. Saturday will be the better day of the weekend with high temperatures in the low-mid 80s and lower humidity. By Sunday, temperatures will begin ramping up into the mid-80s with an increase in humidity. Early next week, we’ll be looking at a continuing warming trend with high temperatures in the mid-upper 80s Monday and near 90 Tuesday before our next chance of rain.