Tag Archives: tropical depression

NYC Special Weather Update: Tropical Depression Eighteen – Oct 28, 2017

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The National Hurricane Center announced that Tropical Depression Eighteen has formed over the northwestern Caribbean Sea just south of Isla de Juventud in Cuba. The formation of TD Eighteen has implications on the forecast for Sunday’s storm as a complex scenario is set to unfold.

Impacts: forecasters are anticipating a high wind, and heavy rain event coming up. Storm total rainfall of 2-4″ and possibly higher could lead to urban and small stream flooding. The amount of rainfall over a short period of time has led our local forecast office to issue flash flood watches for much of the region. Winds will pick up as well, backing from the south to southeast, east, and eventually to north and northwest. Wind gusts could become a problem for local airports and for poor travel conditions in general. Thunderstorms are a possibility as well.

Timing: Winds are already increase today, and cloud cover will do so as well as the day progresses. Chances for rain will increase in the overnight hours, probably after 2-3AM. The strongest wind gusts will actually come on the back side of the storm going into Monday as it intensifies and the pressure gradient increases.

Discussion: a complicated set up is unfolding with a longwave trough (on the left) draping from the Great Lakes into the Gulf of Meixco interacting with a developing closed low over the Tennessee Valley, and TD Eighteen. TD Eighteen is likely to strengthen into a tropical storm, which would be named Phillippe if it did form. The effect of this will be to provide a conveyor of warm and moist air from the tropics up to our area. This will help feed the developing non-tropical low forming over the southeast. This low will become the primary rainmaker, and the tropical system (whether a depression or storm) will eventually merge with it. Plenty of instability to fuel a growing storm! The pressure gradient will tighten as this storm strengthens and departs eastward, and that will be the reason for a gusty start to the work week.

 

NYC Weather Update – May 6, 2015

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A downright summer-like stretch of weather that started this week will get mirrored again towards the end of this week and going into next week. After clearing out clouds today, the remainder of this week should see dry and sunnier weather with highs in the mid-upper 70s. This weekend, we are looking at the possibility of temperatures near 80, nearly 15º above normal. We also have what could turn into the 2015 season’s first tropical depression/storm churning up off the coast of Florida now.

Rest of today – a very slow-moving, largely stationary front pushed through last night, but is still sitting in our vicinity. Along this front, remnants of more organized convective activity will be able to slide east during this afternoon and evening. While the chances are not high, there could still be an occasional shower during the latter half of today, high temperatures will be somewhat subdued around 70 with the clouds in place.

Thursday – clouds will clear out tomorrow and we should have a sunny day with temperatures in the mid-70s.

Friday – a repeat of Thursday, with mostly sunny skies and highs again in the mid-70s.

Saturday – increasing cloud cover, but should still be a pleasant day with temperatures in the upper 70s.

Sandwiched between rain to our south and to our west, but our weather should still remain dry this weekend.
Sandwiched between rain to our south and to our west, but our weather should still remain dry this weekend.

Sunday – warm and pleasant with a high near 80.

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Climate Prediction Center temperature outlook for next week – still looks like we’ll be getting warmer than normal temps

First Tropical System of the 2015 Atlantic Hurricane Season?

As I write this, a low pressure system is building up steadily off the east coast of Florida. The National Hurricane Center puts the odds of this system organizing sufficiently to become the first named tropical depression, subtropical, or tropical storm of the 2015 Atlantic Hurricane Season. Even if this storm does become the first named tropical system, it is unlikely to do much damage as it will have very little time over open water to gain strength before it is forecast to make landfall over the Carolinas later. The most noticeable impact from this storm would be the rain it generates.

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Tropical Depression One Update – Jul 1, 2014

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Overnight, the area of disturbed weather mentioned in my previous post intensified enough that the National Hurricane Center upgraded the storm to the 2014 Atlantic Hurricane Season’s first tropical depression.

As you can see below in a satellite image captured at 7:45AM EDT this morning, TD One is showing increasing signs of organization. You can clearly see overshooting tops (the bubbly looking clumps of clouds), which are clouds that are breaking up through the tropopause and into the lower stratosphere. This is a hallmark sign of intense thunderstorm updrafts, where warm, humid air is rapidly moving upwards in the atmosphere. You can even see the beginning of what may eventually become a spiral band forming directly south of the storm’s center.

National Hurricane Center has issued tropical storm warnings for the Eastern Florida coast. TD One’s sustained wind speeds are at 35mph, only 4mph shy of tropical storm criteria. In fact, as of this writing, TD One may have already become Tropical Storm Arthur, our first named storm of the 2014 Atlantic Hurricane Season.

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Storm Track Forecast

TD One is forecast to begin a turn towards the north, then northeast over the period of the next day or so. Thereafter, it is forecast to steadily accelerate in forward speed towards the northeast as a cold front currently approaching our region from the west begins to steer the storm. It appears in the latest model runs that the storm may make a landfall in the Cape Hatteras area of North Carolina, and the move offshore of the Northeast Friday night into Saturday.

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Intensity Forecast

Although the strongest thunderstorms are currently confined to the southern half of the storm, there is high confidence that the storm will continue to organize and become a tropical storm shortly. The National Hurricane Center is also now forecasting that TD One will have sufficiently good conditions to strengthen into a weak hurricane by the time it makes its closest approach to North Carolina. It will eventually get absorbed by the cold front mentioned above and make an extratropical transition somewhere off the coast of the Canadian Maritimes.

What This Means for Us

The tropical moisture from this storm is increasingly likely to throw a damper on July 4th plans for the area, when the storm and approaching cold front will interact to produce the chance for heavy rain, thunderstorms, and possibly some strong wind gusts. However, even though this is forecast to occur within the next 3-4 days, there is still a good deal of uncertainty as to the final track of this storm, especially as it approaches the Northeast. More updates soon!

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