John Homenuk

Concern builds as Tropical Storm Sandy provides forecasting headache

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European forecast model showing TS Sandy, phased with a trough over the Central US, as a very strong storm at 933mb just off the New Jersey coast. Such a strong storm is almost unprecedented for our area.

Forecast models continue to waiver with track, intensity, and impacts on a potential major storm system developing off the East Coast at the end of this coming weekend and continuing into early next week. Earlier this week we outlined the potential in the long range for a system, but dismissed the hype which was already growing, with some outlets already talking about wind numbers and rain potential. Now that we are a few days closer to the event, and around 5 days away from potential impacts, we have some slightly increased confidence that the storm will at least have a chance of bringing impacts to our area. In essence, the storm isn’t just a “fantasy land” storm on forecast models anymore — it seems to be a legitimate possibility (not a certainty). So, we’ll lay out all details below with a full explanation of the event in which we try to answer any questions you may have in regards to the storm and it’s impact on the weather in the NYC area.

What’s the deal with this threat, why is it developing in the first place? Tropical Storm Sandy formed a few days ago in the Caribbean. The storm is strengthening a bit and is expected to drift northward over the next day or two, into the Northern Carribean and southwest Atlantic. The pattern over the United States and Northern Atlantic ocean is completely blocked up (i.e, the pattern is very amplified, with unusually deep troughs and ridges thanks to a very low NAO and AO index). This means the steering flow (what guides the tropical storm) will bring it out of the Caribbean and then on a north, possibly northeast heading for a while. More often than not, storms in this position head out to sea. But as you can see in this diagram, there is not much room for Sandy to do that. The ridge axis building over the top of her and to her east over the Atlantic remains strong. And to the west of her, over the Central US, you can see a trough beginning to dive south and east.

Keep reading for details, diagrams, and thoughts on the potential threat…

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John Homenuk

Forecast: Cloudy start, but clearing for the weeks end

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NAM forecast model showing low temperatures the morning of Wednesday 10/23/12. Notice how temperatures remain in the 60’s overnight, especially near the warmer oceans.

A stationary/slowed warm front near the area caused unsettled weather beginning on the second half of Tuesday. The unsettled weather is expected to continue through Tuesday Night and into early Wednesday, with a chance of showers continuing throughout parts of the area and clouds hanging around for a while. By later Wednesday, the front will be on the move to the north and east, which should help move the clouds and showers out of the way at least briefly. We aren’t expecting a big warm up, though, as the area will remain in a cool “pocket” of mid level temperatures while areas in the Mid-Atlantic get warmer. Still, high temperatures will get into the 60’s on Wed-Thu and possibly warmer than that on Friday where we could see temperatures move into the mid 70’s in parts of the area.

Tonight:  Mostly cloudy with periods of light rain expected overnight. Southeast winds around 10 miles per hour — raw with the winds off the water for much of the area. Temperatures falling only into the middle 50’s (closer to 60 in the city and near the water). Bring a sweatshirt and/or an umbrella if you’re headed out.

Wednesday: Light rain expected in the morning, with mostly cloudy skies. The rain will become more sporadic by afternoon, with some breaks in the clouds possible…but drizzle will remain a possibility through the day. High temperatures in the 50’s and 60’s north, 70’s south (over Southwest NJ).

Weekend Storm Update: Generally status quo on the potential significant storm system this weekend. Forecast models are still split on potential with roughly half of them keeping the Tropical Storm un-phased with the Eastern US trough and out to sea, while the other half phase the two and bring a large powerful storm near the area (with heavy rain, high winds, beach erosion..i.e a very high impact system). Uncertainty is still higher than normal for a medium range forecast. We will have a full post with updates and potential scenarios up either late tonight or Wednesday.

Stay tuned to our Facebook and Twitter for continuous updates!

 

Doug Simonian

Forecast: Unsettled Tuesday, improving by mid to late week

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NAM Forecast model showing showers and plenty of clouds in the area on Tuesday Night into Wednesday morning. Clearing is expected by later on Wednesday afternoon.

A stationary front to our north will provide the area with cloudy skies and the chance of showers throughout today and tomorrow. Your morning commute should be dry, but once the afternoon rolls along, the chance of showers will increase. It will not be a washout, but it’s probably still a good idea to keep the umbrellas handy just in case. Temperatures will remain mild, however, with highs in the mid 60s, as the eastern half of the country remains in a ridge.

The best chance for heavier rain, however, will be overnight tonight into early tomorrow morning, as a weak shortwave moves into the area, enhancing the lift and moisture associated with the stationary front. The NAM simulated radar for tomorrow night shows the heavier showers pretty well. The showers for the most part will have moved out by tomorrow afternoon, but a few still may linger, and skies will still be mostly cloudy.

The front will clear the area by tomorrow night, and the resulting weather should certainly improve for Thursday and Friday. Some clouds will still linger, but the sun will be out and temperatures should rise into the upper 60s and lower 70s.

Today: Skies will become overcast and showers will be around the area for the afternoon, especially for locations north of the city. Highs will be in the mid 60s.

Tonight: Showers become a bit more numerous, with moderate to heavy rain even possible at times. The whole night won’t be a washout, but definitely have the umbrellas handy. Temperatures will fall into the upper 50s.

Tomorrow: Early morning showers should give way to primarily mostly cloudy and cloudy skies, with isolated showers around. Highs will be in the mid and upper 60s.

Keep reading for more details including an update on the potential tropical system this weekend..

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John Homenuk

Hype meter rising on potential weekend storm: What’s the deal?

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ECMWF Forecast Model showing a very strong storm system off the East Coast early next week. It is one of a few models showing the potential system in the long range (beyond 6 days).

The meteorological community is buzzing in regards to the potential for a major storm system this weekend, which could affect much of the Eastern United States. Local media has caught on to the potential and is beginning to hype up the potential storm system — as are several weather forecast outlets in the area. However, it is important to remember that the system is still floating around in what meteorologists like to call “Fantasy land” on forecast models. The range where, especially in a high amplitude pattern, models are prone to wild and wacky solutions. In this case, we’re seeing some of the wildest solutions in recent memory — and it’s causing the meteorological community to hype up the potential for a major storm. That being said, taking a look at some of the pieces of the pattern can offer us clues as to where the potential actually lies — aside from the wild model guidance images floating around the internet. We’ll try to answer some of the questions we’ve had emailed/tweeted/facebooked at us throughout the day today.

Why is there a storm threat, where is it developing? One of the major causes behind the threat for a significant storm is the development of a tropical system (Tropical Depression 18) and a large trough over the Central United States, which is then forecast to surge south and east and phase with the tropical system. A phase occurs when two or more pieces of the jet stream interact with one another. In this case, the Central US (northern stream) trough could surge south and east to phase with the tropical entity by next weekend.

Keep reading for a full discussion on the potential and hype…

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