tight precip gradients with coastal storms....whoooweee what up wid dat?

[NJHurricane]

A topic which keeps crowding other threads. Almost every significant system the past two years has featured tight precip gradients, often hugging the coast. Is this dominance of southern stream sytems? Lack of GOMEX originating storms? Seems like its not just in winter but also fall/spring noreasters as well. I welcome thoughts on this recurring phenomena, its causes and if we are likely to see a near term return to systems with more balanced qpf distrubution.

[am19psu]

My opinion is that it has been due to the rapid deepening we've been seeing off the Jersey coast. When you tighten the gradients that quickly, you develop both CSI and strong frontogenetic forcing from the deformation terms on the mesoscale. Outside of those areas, you often see strong subsidence because what goes up must come down. In storms that do not develop as quickly, the pressure gradients are often weaker (even if the central pressure is lower) and produce more synoptic scale lift (i.e DCVA and warm advection), which allows for a larger precip shield.

[NJHurricane]

My opinion is that it has been due to the rapid deepening we've been seeing off the Jersey coast. When you tighten the gradients that quickly, you develop both CSI and strong frontogenetic forcing from the deformation terms on the mesoscale. Outside of those areas, you often see strong subsidence because what goes up must come down. In storms that do not develop as quickly, the pressure gradients are often weaker (even if the central pressure is lower) and produce more synoptic scale lift (i.e DCVA and warm advection), which allows for a larger precip shield.

Its weird...it seems like ages since we got overrunning precip from a primary low to our west followed by a gradual coastal transfer. I can remember in the early 2000,'s some of our better snowfalls being preceded by accumulating snows in Chicago,Indy,Cincy and Pittsburgh....past couple years Harrisburg to State college might as well be wyoming when it comes to these systems.

[sn0w]

My opinion is that it has been due to the rapid deepening we've been seeing off the Jersey coast. When you tighten the gradients that quickly, you develop both CSI and strong frontogenetic forcing from the deformation terms on the mesoscale. Outside of those areas, you often see strong subsidence because what goes up must come down. In storms that do not develop as quickly, the pressure gradients are often weaker (even if the central pressure is lower) and produce more synoptic scale lift (i.e DCVA and warm advection), which allows for a larger precip shield.

Another reason that coastal regions which are typically mostly rain in these storms have been getting hit with big snows instead?

[earthlight]

The coastal systems will more often that not feature sharp cutoffs on the northwest fringes of precipitation, whether they are modeled correctly or not.

Strong upward vertical velocities and omega (lift) along with the areas of frontogenesis and deformation banding of snow are common. But on the fringes of these amazing mesoscale features often comes strong subsidence, hence the sharp gradients in the snowfall. This is especially true when the area of cavorts forcing doesn't move much.

February 2006, December 2010, March 2009, they all featured all of those things. Where there's a big winner, there's a big loser, and that's the way these deformation banding bombs have to work in atmospheric terms.

[earthlight]

My opinion is that it has been due to the rapid deepening we've been seeing off the Jersey coast. When you tighten the gradients that quickly, you develop both CSI and strong frontogenetic forcing from the deformation terms on the mesoscale. Outside of those areas, you often see strong subsidence because what goes up must come down. In storms that do not develop as quickly, the pressure gradients are often weaker (even if the central pressure is lower) and produce more synoptic scale lift (i.e DCVA and warm advection), which allows for a larger precip shield.

Watching all of these coastal bombs evolve is really a treat in itself. It's been a good while since we've seen one of those longer duration overrunning events, where the precipitation is more spread out over a large swath of land.

[Bluescat1]

Watching all of these coastal bombs evolve is really a treat in itself. It's been a good while since we've seen one of those longer duration overrunning events, where the precipitation is more spread out over a large swath of land.

It is also fun when the bands set up over your house, when they don't not so much. I was lucky with the last storm, I picked up most of my 8 inches with the banding. Last year when MD DC and SW PHL had all the action all I could do was watch the bands fizzle as they crossed the Delaware out of Philly.

[Voyager]

I said this last night and it was quickly deleted.

It's not the lack of snow so much that bothers me, but the tight gradients. I could live with a snow drought if it was because most of the storms slid OTS off the Carolina coast, or cut to the lakes and gave us rain, but to be literally 30-50 miles from a SECS or MECS, and be able to sweep my sidewalk with a broom is frustrating.

[Grothar]

I said this last night and it was quickly deleted.

It's not the lack of snow so much that bothers me, but the tight gradients. I could live with a snow drought if it was because most of the storms slid OTS off the Carolina coast, or cut to the lakes and gave us rain, but to be literally 30-50 miles from a SECS or MECS, and be able to sweep my sidewalk with a broom is frustrating.

You went against the establishment- specifically NYC establishment. You posted this gradient concern in the right thread

[NJHurricane]

Watching all of these coastal bombs evolve is really a treat in itself. It's been a good while since we've seen one of those longer duration overrunning events, where the precipitation is more spread out over a large swath of land.

Yeah...its fun especially if you are under it...for those whose weather passion is limited to what they personally experience it sucks to be outside of it. If you are in to understanding the physical process behind it, fun as well. I guess I am weird, I always had a fetish for the more wide scale precip events. 1993 superstorm was one of my favorites growing up and still is....I love the idea that a storm is bringing almost equally paralyzing conditions not just across a metro region, or even a state...but across multistate regions and time zones.

Kind of amazed with this storm...that it does have a gulf connection, but if some of the modeling is correct due to the parallell cut-off 500h low and the defo zone with concentrated area of insane vv's....same results in the northern Mid-Atlantic

[jwilson]

I'm looking forward to the next overrunning event, whenever that may be. These tight gradients are difficult to deal with and 95% of the time I'm on the wrong side of them. Does it have something to do with the ENSO state? I'm not sure if that has any true effect although I imagine the moisture availability in the GOF does have at least some effect.

[RedSky]

The coastal systems will more often that not feature sharp cutoffs on the northwest fringes of precipitation, whether they are modeled correctly or not.

Strong upward vertical velocities and omega (lift) along with the areas of frontogenesis and deformation banding of snow are common. But on the fringes of these amazing mesoscale features often comes strong subsidence, hence the sharp gradients in the snowfall. This is especially true when the area of cavorts forcing doesn't move much.

February 2006, December 2010, March 2009, they all featured all of those things. Where there's a big winner, there's a big loser, and that's the way these deformation banding bombs have to work in atmospheric terms.

But i have been an avid winter storm watcher in PA for thirty years and save one storm in the late 80's that pummeled south jersey while i received a coating there has never been a run of benchmark storms like this that have featured this drastic cutoff in eastern PA. It started with blizz 2006 and has not let up. It's starting to feel like the new norm

Now the reasoning put forth for last winters storms and the december storm was the block and powerfull 50/50 causing the gradients, this next storm has none of that and yet...

[Voyager]

But i have been an avid winter storm watcher in PA for thirty years and save one storm in the late 80's that pummeled south jersey while i received a coating there has never been a run of benchmark storms like this that have featured this drastic cutoff in eastern PA. It started with blizz 2006 and has not let up.

100% spot on.