Tag Archives: severe wx

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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Weekend Weather, Hurricane Arthur Update – Jul 4, 2014 @ 10AM EDT

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As of 9AM EDT, Hurricane Arthur has weakened somewhat from its peak intensity as a Category 2, and sustained winds have declined to 90mph. However, its eye is still clearly visible, and as you can see below, the storm is maintaining a symmetrical appearance with good outflow in all quadrants, meaning this is still quite a powerful storm. As Arthur continues moving northeast, it is expected to weaken rapidly upon entering much cooler waters and with increasing vertical shear from the codl front seen below.
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Track Forecast

Forecast models are in very close agreement about Arthur’s track over the next 12 hours or so. As you see below, they are tightly clustered around the 40N, 70W benchmark. Hence, forecast reasoning has not changed much since yesterday night. Arthur is expected to continue its northeast track and speed up under the influence of the cold front depicted above, moving offshore of New England and into the Canadian Maritimes as it makes extratropical transition.

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What This Means for Us

As expected, Arthur will be bringing multiple rounds of rain to the entire Northeast over the course of the day today. You can already see Arthur’s outer rain bands on our regional radar (you’d see it in the standard 124 nautical mile radar, but I’ve inserted an image of 248 nautical mile range radar image to see the storm better). As Arthur accelerates and makes its closest pass to this part of the country, we’ll see repeated bands of rain moving on shore. You can expect periods of heavy rain and thunderstorms, interspersed with some dry spells under cloudy skies.

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The Rest of the Weekend

Once Arthur and the cold front clear the Northeast, we will see a return to a spectacular weekend with high pressure building back in. Sunny skies, mild, and dry conditions will prevail across the entire region with high temperatures in the low-mid 80s on both Saturday and Sunday. As the high pressure moves to our southeast, we’ll see a return flow from the backside of the high pressure ushering in another warm, humid airmass for the beginning of next week.

 

NYC Weekend Weather – Hurricane Arthur – Jul 3, 2014

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Lots going on in the realm of weather over the coming weekend. First, to start off with today, the Storm Prediction Center has again placed our area under a slight risk of severe weather this afternoon and evening. We could see a repeat of the type of storms from last night as a cold front makes its approach from the west. Even though temperatures are lower today and sunlight limited, there’s still more than enough instability in the atmosphere to fuel a few strong to severe thunderstorms later today. Because we’re looking at another round of possibly torrential rain from today’s storms, many areas are under a flash flood watch. Part of this moisture is due to the influence of Hurricane Arthur to our south.Untitled3

Hurricane Arthur

As of this morning, Arthur strengthened into the 2014 Atlantic Hurricane Season’s first hurricane and is currently sitting offshore of South Carolina with sustained winds of about 90mph. Forecasters are increasingly confident that Arthur will have enough time over warm water and low wind shear areas to grow into a Category 2 storm before getting recurved out to sea and making extratropical transition.

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Track Forecast for Hurricane Arthur

Arthur is now forecast to brush by the Outer Banks of North Carolina sometime later today, and move to just about the 40N, 70W benchmark offshore of the Northeast by 8PM Friday. Given this current forecast track, confidence is increasing that we’ll continue to see heavy rain and showers through out Friday into Friday night, though not directly from Arthur itself. Rather, Arthur will be interacting with that cold front mentioned above to throw a wrench in everyone’s July 4th plans. Conditions should begin to improve rapidly Saturday as Arthur accelerates northeast, pushed by the cold front. We should see a return to sunny skies and seasonable weather Saturday with highs around the low 80s. Of particular concern are areas in Southeastern New England, which could see tropical storm conditions on Friday night into Saturday morning. Any deviation westward of this current forecast track would mean increased impacts on the Northeast, so this storm is worth watching closely. Regardless, high surface and dangerous riptides will be present on all Atlantic shorelines.

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NYC Nowcast – Jun 13, 2014

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You’ve felt the air warm up and become more humid as the warm front that brought our first round of rain passed through earlier today. Now, we’re getting set for a second round of heavy showers and thunderstorms associated with a pre-frontal trough that’s slowly progressing east towards the area from Eastern Pennsylvania.

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Ahead of this line of showers and thunderstorms, the air has destabilized readily with the ample sunshine earlier this afternoon. CAPE (Convective Available Potential Energy – a measure of how much fuel there is for thunderstorms to feed off of) is between 1000-1500 J/Kg over Northeastern New Jersey and NYC. This should allow for this line of storms to hold up and perhaps strengthen before hitting NYC. In fact, a couple sever thunderstorm warnings have already been posted for cells over Northeastern New Jersey.

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