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Super Snow Sunday 2/15-Party Like it's 1717


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Happiness is coming back to the board after an hour and see 10+ new pages. You know the Euro is da bomb and have fun as the anticipation builds. Let's lock 12Z Euro please

 

Ah, but we know that we cannot lock a 96hr look. It's Wednesday. This doesn't arrive -- in theory -- until Saturday night. 4 days out, there will be wiggles.

 

Right now the main takeaway is that the consensus has shifted toward and earlier "pop" and as a result there is a greater likelihood of impact -- perhaps significant -- for portions of New England, greatest on the eastern edges.

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We really need about 2 more runs to start getting very high confidence. The storm is commencing around the 84 hour mark, so we are definitely not in marginal clown range or anything...but it is usually that 84-96 range where we see the models...in particular the Euro..."make their move"...so tonight's runs will be especially important.

 

We've already seen 2 "moves" in a row at 00z and now 12z, so hopefully it's the models beginning to tip their hand, and not some burp or start of an even greater move that takes us out of it.

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Man, if that pans out, the ridiculously far-fetched idea of someone pulling 100" in 30 days suddenly seems quite obtainable…Wow...

 

 

ORH is at 78.2" since 1/24...so they need 21.8" by February 24th to get 100" in a month...if this storm can give them 15, then it looks really attainable.

 

There are probably some spots on the interior south shore over 80" in that same time period...so they are even closer. But doing it at a first order site would be fun.

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RIP coastal communities within 20-30 miles of boston....

If there is serious flooding involved this will be a tough pill to swallow.

I am starting to get scared...For less educated/aware people. What happens when we get the pounding rain and 35-40f SE MA is oh so familiar with.

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Cool little read.

 

TEMPERATURE AND TROWAL

 

Richard Pollman, Lead Meteorologist at the National Weather Service Office in Detroit says strong convection is the basic building block for frontogenesis forcing. “You might have a trough of warm air aloft within and stacked occluded system combining with TROugh of Warm air ALoft (TROWAL). All of these things work together to create instability.” Pollman also notes that it is important to consider Conditional Symmetric Instability where the movement of the parcel slanted, rather than straight up.

“Storms occluding on top of you are in the deepening phase, causing a deeper storm than one that occludes to the left of you,” Pollman says. His forecasting team looks for warm or occluded fronts as the first building block for frontal forcing. He says the extreme forcing occurs because the convergence and lift is over a concentrated area. “Lifting the moist, unstable air with added lift from convection helps the parcel to precipitate out,” he adds.

TROWAL is defined by Professor James T. Moore of the Cooperative Institute for Precipitation Systems at St. Louis University as a 3D sloping intersection of the upper cold front portion of the warm occlusion with the warm frontal zone. It is a wedge of warm air on top of cold air. He points to the exact location of TROWAL is usually along the ridge of high Theta-e values. It is the cyclonic portion of the warm conveyor belt that wraps around to the NW of the cyclone.

Pollman says, “TROWAL is between 700- 500 mb level. Frontal forcing is usually stretched from the surface up through to the 500 mb level, but most commonly found around 850 mb. It is a ridge of theta e extending into the cold sector of the storm. You can find it by looking at the 500-700 mb plan view of theta e. Trowel does enhance the lift, like summertime CAPE. And often, the TROWAL and forcing is accelerated within this winter instability. He says it is hard to forecast. “Usually there are three or four f-gen bands, but only a couple of them really come active.”

This banding can result in a blown forecast. Meteorologists may be able to forecast the large scale synoptic event, but locating the meso bands is more difficult until the storm is about two hours away. Weather balloon measurements may miss the entire event. This is another cause for missing the banding effect. Since balloons are released only every 12 hours, the banding event could have occurred in the middle of the launchings and go undetected until it shows up on radar. Meteorologists may have forecasted two to three inches of accumulation, when the stationary frontal forcing caused over six inches to fall. Pollman says there isn’t one specific thing that can be done to accurately predict where the heaviest snow fall will be. He says, “ You have to keep monitoring them on radar hour by hour.”

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is this what helps pull the precip back further west?

 

Well I would say you want one that is established. It's also similar to what a CCB is..a conveyor belt of moisture that rides up and up along a sloped thermal surfaces (known as potential temp or theta surfaces). Every storm has one, but this was well defined. 

 

Anyways, it's a detail not to be weenie'd out on 4 days out...was just noting a very cool thing.

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