Late February/Early March Medium and Long Range Discussion Thread

[Dsnowx53]

we need the system on wednesday to trend weaker or move east for us to have a better chance

feb 2010 had an initial wave before the main event on the 25th. it was weak enough to allow the system behind it to amplify

 

 

But wouldn't that compress the height field off the coast more, though? I actually want the Wednesday system further west, since that essentially will represent the position of the ULL. And the further west the ULL is, the further west the trough base, and the further west any phasing between ULL energy and the energy trying to round the base would be. 

[snywx]

But wouldn't that compress the height field off the coast more, though? I actually want the Wednesday system further west, since that essentially will represent the position of the ULL. And the further west the ULL is, the further west the trough base, and the further west any phasing between ULL energy and the energy trying to round the base would be. 

 

And thats exactly what happened with the initial wave before the "snowicane"

 

The coast rained while the interior received a warning snow event..

[earthlight]

But wouldn't that compress the height field off the coast more, though? I actually want the Wednesday system further west, since that essentially will represent the position of the ULL. And the further west the ULL is, the further west the trough base, and the further west any phasing between ULL energy and the energy trying to round the base would be.

I think there's some validity to the idea that the stronger and farther west the initial upper level low is, the farther east the second vort will be kicked. Sounds backwards, but the models that are stronger like the GFS have a more expansive ULL and surface low that kicks the front east. So the second shortwave doesn't amplify until it's well out to sea.

This is a very convoluted setup despite being favorable..which is why it was so remarkable that Feb 26 2010 worked out the way it did. When you think about how intricate and perfect the timing would have to be in order for this to hook back towards the coast..you get an appreciation for that.

[Dsnowx53]

I think there's some validity to the idea that the stronger and farther west the initial upper level low is, the farther east the second vort will be kicked. Sounds backwards, but the models that are stronger like the GFS have a more expansive ULL and surface low that kicks the front east. So the second shortwave doesn't amplify until it's well out to sea.

This is a very convoluted setup despite being favorable..which is why it was so remarkable that Feb 26 2010 worked out the way it did. When you think about how intricate and perfect the timing would have to be in order for this to hook back towards the coast..you get an appreciation for that.

 

 

I'm not sure there is a correlation between strength and elongation, though. But I could be wrong. 

 

I still think all else being equal strength wise, you want the ULL to be further west. Ideally, further west and compressed. But even that being said, I'd still rather a strong and west ULL rather than a weaker and east ULL. The intricacies with this type of evolution are quite high, of course, but I think from a synoptic standpoint, especially considering the progressive problems we've run into this winter, a further west trough base would reduce the margin of error.  

[Dsnowx53]

If you look at 500mb with the GFS at 132 hours vs the Euro at 132 hours, they actually aren't too terribly different.

 

But when you look at the height contours closely, you can see that there are more closed contours from the ULL covering a more westward longitude on the Euro. That helps the buckle the pattern in the Plains ever so slightly more compared to the GFS, and thus you have a more potent, meridional oriented vortmax at the base of a sharper, further west trough base than you do on the GFS. This is why the Euro is much closer to a huge snowstorm for us in the day 7 period than the GFS is. 

[earthlight]

I'm not sure there is a correlation between strength and elongation, though. But I could be wrong.

I still think all else being equal strength wise, you want the ULL to be further west. Ideally, further west and compressed. But even that being said, I'd still rather a strong and west ULL rather than a weaker and east ULL. The intricacies with this type of evolution are quite high, of course, but I think from a synoptic standpoint, especially considering the progressive problems we've run into this winter, a further west trough base would reduce the margin of error.

Yeah I can agree with that. I think the size of it will come into play as well with the suppression of the height field as we mentioned. But the farther east solutions with the center of the ULL tracking over NY State would essentially reduce our chances of seeing something pretty dramatically.

The Euro evolution is pretty awesome to watch though..the comparisons to Feb 26 are definitely there with the coastal low hooking back towards New England despite swinging outside the 40/70 benchmark.

A few more amplified trends with the SE Ridge and we could see some wild solutions..but will the blocking be enough to buck the seasonal trend of progressive/southeast?

[SnoSki14]

Yeah I can agree with that. I think the size of it will come into play as well with the suppression of the height field as we mentioned. But the farther east solutions with the center of the ULL tracking over NY State would essentially reduce our chances of seeing something pretty dramatically.

The Euro evolution is pretty awesome to watch though..the comparisons to Feb 26 are definitely there with the coastal low hooking back towards New England despite swinging outside the 40/70 benchmark.

A few more amplified trends with the SE Ridge and we could see some wild solutions..but will the blocking be enough to buck the seasonal trend of progressive/southeast?

 

Considering we haven't had a strong blocking event this winter thus far,, I would say sure, why not. Different pattern equals different results in this case.

[Edge Weather]

The control run at  150 hrs starts to consolidate the low near or 100 miles off the Delmarva hard to tell, then at 156 hrs has a 990mb low about 150 miles east of Sandy Hook, at 162 hrs it deepens the low to 982 near the Benchmark with heavy precip for Eastern long Island up through New England, then at 168 hrs it has a 976mb low between Cape Cod and Boston with all of New England being slammed, then it stalls it out over Boston.  Areas to the west of Eastern Long Island are basically dry slotted for the entire storm, even Philly and DC got a bit of precip before it consolidated, but we are caught between and dry slotted, except for Eastern Long Island that gets hit reasonably well.

[PB GFI]

Its not the ridge you need out ahead of it , its the block , the stronger the block the more supressed the system becomes , you want the center only so far north before its able to get forced west , a stronger ridge may not  get you to the  lattitude you want , but a stonger standard deviation from normal may . The Euro control once again takes this into SNE , we arent that far away , but seeing  the March 2001 anolog  leaves a bad taste in my mouth  

 

 

Trying to figure out where this wants to retrograde , I went back and looked  at the NAO during Sandy and it was a neg 2 standard deviation from normal , during next weekends time frame the NAO looks to be about  a 1 standard deviation from normal and that may allow this to slip further north   , its not the end all be all  , but it has to be looked at IMO .

[Eduardo]

I think there's some validity to the idea that the stronger and farther west the initial upper level low is, the farther east the second vort will be kicked. Sounds backwards, but the models that are stronger like the GFS have a more expansive ULL and surface low that kicks the front east. So the second shortwave doesn't amplify until it's well out to sea.

This is a very convoluted setup despite being favorable..which is why it was so remarkable that Feb 26 2010 worked out the way it did. When you think about how intricate and perfect the timing would have to be in order for this to hook back towards the coast..you get an appreciation for that.

 

Is it fair to characterize March 2001 as a similar instance, save for imperfect timing?

[IntenseBlizzard2014]

The control run at 150 hrs starts to consolidate the low near or 100 miles off the Delmarva hard to tell, then at 156 hrs has a 990mb low about 150 miles east of Sandy Hook, at 162 hrs it deepens the low to 982 near the Benchmark with heavy precip for Eastern long Island up through New England, then at 168 hrs it has a 976mb low between Cape Cod and Boston with all of New England being slammed, then it stalls it out over Boston. Areas to the west of Eastern Long Island are basically dry slotted for the entire storm, even Philly and DC got a bit of precip before it consolidated, but we are caught between and dry slotted, except for Eastern Long Island that gets hit reasonably well.

I find that a tad bit unrealistic of the dryslotting. Unless if the storm goes East of the Benchmark.

[forkyfork]

But wouldn't that compress the height field off the coast more, though? I actually want the Wednesday system further west, since that essentially will represent the position of the ULL. And the further west the ULL is, the further west the trough base, and the further west any phasing between ULL energy and the energy trying to round the base would be. 

the far lower right ensemble member shows us getting a storm and it moves the closed low to the 50/50 position beforehand

http://www.meteo.psu.edu/~fxg1/ENSHGT_12z/ensloopmref.html

[Dsnowx53]

the far lower right ensemble member shows us getting a storm and it moves the cutoff to the 50/50 position beforehand

http://www.meteo.psu.edu/~fxg1/ENSHGT_12z/ensloopmref.html

 

 

Ohh okay. Yeah, if we can get it to move all the way to the 50/50 low position, then that would also benefit. But that's also a very different evolution than what is being modeled with the potential for the ULL to phase in. 

 

Edit: Additionally, that would push the main threat out several days. If we want the March 1 event with the ULL phase/retrograde, we want the ULL to be further west. If we want the March 3-4 event with the wave amplifying from the base of the downstream trough via the strong PNA ridge, then we want that ULL to move out of the way. Not sure we can get both threats. 

[Heisy]

Not sure if GFS will "do it", but it took a step towards EURO for sure. 

[forkyfork]

Ohh okay. Yeah, if we can get it to move all the way to the 50/50 low position, then that would also benefit. But that's also a very different evolution than what is being modeled with the potential for the ULL to phase in. 

 

Edit: Additionally, that would push the main threat out several days. If we want the March 1 event with the ULL phase/retrograde, we want the ULL to be further west. If we want the March 3-4 event with the wave amplifying from the base of the downstream trough via the strong PNA ridge, then we want that ULL to move out of the way. Not sure we can get both threats. 

we're just not going to get a storm with a large disorganized closed low overhead or over new england

[Dsnowx53]

we're just not going to get a storm with a large disorganized closed low overhead or over new england

 

 

Of course not. But the Euro showed that closed low in the Upper Midwest/Great Lakes region. That's one reason why it was close with the March 1 threat. Having it over New England would be terrible. 

[earthlight]

we're just not going to get a storm with a large disorganized closed low overhead or over new england

 

The Euro has the center of the closed low over or just east of Chicago. So the vort that comes out of the Pac NW digs towards the MS river, and then hooks northeast up the coast and phases. A slightly farther west version of that would be ideal for us and would probably bring a very strong coastal low back in from the coast similarly to Feb 26 2010.

 

If the GFS has the right idea...this is a cold/dry pattern.

[Dsnowx53]

We either want the ULL to go a tick west of where the 12z Euro and 12z GFS have it; or, we can have the ULL move all the way out of the way to the 50/50 region. 

 

I feel like it might make more "sense" to hope that the block buckles the pattern more and forces things west. 

[SnoSki14]

The Euro has the center of the closed low over or just east of Chicago. So the vort that comes out of the Pac NW digs towards the MS river, and then hooks northeast up the coast and phases. A slightly farther west version of that would be ideal for us and would probably bring a very strong coastal low back in from the coast similarly to Feb 26 2010.

 

If the GFS has the right idea...this is a cold/dry pattern.

 

The gfs will figure it out as will the rest of the models, this is the best the pattern has looked thus far and I'll be shocked if we don't benefit. 

[ag3]

The Euro has the center of the closed low over or just east of Chicago. So the vort that comes out of the Pac NW digs towards the MS river, and then hooks northeast up the coast and phases. A slightly farther west version of that would be ideal for us and would probably bring a very strong coastal low back in from the coast similarly to Feb 26 2010.

If the GFS has the right idea...this is a cold/dry pattern.

Exactly. Look at Feb. 26, 2010 and the position of that ULL.

It was a bit west of where today's 12z euro was.

[Dsnowx53]

For the March 1 threat, I think we definitely want the ULL to be forced west to the Chicago area or so. 

 

For the threat a few days after that, we can have the ULL either be in the Chicago area, or way out of the way to the 50/50 region. 

[Dsnowx53]

Not sure if GFS will "do it", but it took a step towards EURO for sure. 

 

 

In my opinion, it actually took a step away from the Euro, as it made the ULL much more elongated, and shifted it further east. Thus, the trough axis is way too far east for the March 1 threat and any phase would occur well offshore. 

[Dsnowx53]

However, the 18z GFS is much more favorable with its PNA ridge compared to the 12z GFS, which gives more room for the further east ULL to still capture the out to sea low and bring it back a bit to the west. 

 

What I'm trying to get at is that perhaps we can keep the ULL where the 12z Euro and even the 12z GFS currently have it...IF we can get the ridge out west to trend even more amplified and meridional. 

[NEG NAO]

This from SPC today in the 6 - 10 day outlook

NEAR-TO-ABOVE MEDIAN

PRECIPIATION IS FAVORED ALONG THE EAST COAST AS WEAK SHORTWAVES ROUNDING THE

MEAN TROUGH COULD EXCITE SOME CYCLOGENESIS NEAR THE COAST

http://www.cpc.ncep.noaa.gov/products/predictions/610day/fxus06.html

And this from HPC

OF NOTE...REGENERATION OF A SERIES OF SECONDARY SURFACE WAVES

ORIGINATING IN THE SOUTHEAST AND MID ATLANTIC STATES IS A VERY

REASONABLE CONCLUSION WITH THE UPPER-LEVEL PORTION OF THE CYCLONE

REMAINING IN PLACE BEYOND DAY 4.5 AND LIKELY TO WOBBLE IN

SOUTHEASTERN CANADA AND THE NORTHEAST THROUGH DAY 7.

http://www.hpc.ncep.noaa.gov/discussions/hpcdiscussions.php?disc=pmdepd

[IsentropicLift]

00z GFS, ULL retrograding back to Lake Huron this run. Coastal popping near Ocean City, MD. This run might do it.

[IsentropicLift]

Major steps towards a big storm this run. Hr 138 low pressure tracking inside the benchmark, about 100 miles east of ACY. Southern NJ into moderate/heavy snow, up to about Staten Island. Light snow extending into New England.

[MJO812]

The block on this run is stronger. Amazing .

[Zir0b]

Major steps towards a big storm this run. Hr 138 low pressure tracking inside the benchmark, about 100 miles east of ACY. Southern NJ into moderate/heavy snow, up to about Staten Island. Light snow extending into New England.

the H5 evolution from hrs 96 and on looks very strange... i don't think it's right 

[IsentropicLift]

Coastal tracks right over the benchmark at hr 144. Moderate snow extending back to about the DE river, maybe a little further east. Light snow back to PA. Western Long Island getting it good. From hours 144-150 the system is basically 150 miles east of Cape Cod with precip still over the area. Probably a norlun trough? Precip shutting off around hr 159. 0.50"+ for everyone. Less west of KMMU and more, close to an inch from the city east to about the Suffolk county line, some of that from the norlun.

[SnoSki14]

Just the look of it on the gfs is stunning. What a massive system with widespread low pressure throughout. What it's missing is more southern stream involvement, but if the gfs continues to trend with the positioning of the ULL and the energy rounding the base further south and west, than we could see much more moisture with this. Could be a very memorable event if things play out correctly.