Re: March 13th-14th 2023 Big Dog Potential

by **Quietace** Sat Mar 11, 2023 11:29 am

Some subtle shifts so far on the 12z guidance. On the GFS, ICON, and CMC the southern jet is a bit further north which allows for PER of the 250 hPa jet to be closer to our region. This also forces the southern stream energy a tad north, and when combined with a slightly slower northern stream 500 hPa ULL, allows for a double low structure to form.

There are essentially two main areas of peak favorability for cyclogenesis:
1) offshore: from the CVA and differential thermal advection from the southern stream. This area is also being enhanced by the single jet structure, where a broad area of vertical motion is favored in the PER of the jet. This is the "main" low.
2) Closer to the coast: this second low is forming as a result of the same reasons above, but mostly due to the approaching ULL trough creating a extremely favorable location for cyclogenesis. This is the classic location for the low level extratropical cyclone to form given the general dynamical and thermal favorability for height falls and extratropical cyclone development.

The questions become:
1) Will the southern stream vorticity be far away enough to not be directly "attached" to the separate ULL forcing. Or is it being modeled to fast and to far south?
2) If it is too far ahead of the UL feature, will it be the dominant low? If so, how can this secondary low impact thermals and create enhanced frontogenesis areas near it to impact the coastal tristate region? If it is not, how quickly does the low develop, and when does it cut off and move left longitudinally, and how does that impact the precipitation extent back into the tristate area?

by **Frank_Wx** Sat Mar 11, 2023 11:54 am

Impressive trend in the latest GFS run. The trough is more robust and does a better job of controlling the H5 energy. The energy ahead of the ULL - the southern piece Ryan is talking about - is causing tremendous uncertainty with how this plays out at the surface.

March 13th-14th 2023 Big Dog Potential - Page 3 Gfs_z500trend_us_6

March 13th-14th 2023 Big Dog Potential - Page 3 Gfs_z500trend_us_6

by Coachgriff Sat Mar 11, 2023 11:59 am

Great analysis! Really interested to see how this one actually plays out in the end. At this point it appears most of NJ is out of the game with daytime highs on Monday near 50 and lows near 40. Hoping the members north and west get a real snow storm!

by **sroc4** Sat Mar 11, 2023 12:02 pm

Coachgriff wrote:Great analysis! Really interested to see how this one actually plays out in the end. At this point it appears most of NJ is out of the game with daytime highs on Monday near 50 and lows near 40. Hoping the members north and west get a real snow storm!

No way most of Nj is out of anything coach. Pay no attention to your temps

by **Frank_Wx** Sat Mar 11, 2023 12:04 pm

To better show the trend - here's a look at how the location, valid Monday afternoon, of the H5 ULL has trended in the last four (12z/00z only) GFS runs. The top 'X' is four runs ago. The purple 'X' is today's 12z run.

South and west. That is the trend you want.

March 13th-14th 2023 Big Dog Potential - Page 3 500mb-trend

March 13th-14th 2023 Big Dog Potential - Page 3 500mb-trend

by **jmanley32** Sat Mar 11, 2023 12:05 pm

So i am hearing a lot of different analysis for any given area when do we think we start to hone in on if this is go be a bust for coastal.areas or a win or anywhere else that is? Euro and nam showed sig snow for nyc but i guess you guys feel its wrong. I know heehaw already feels its not go b our storm. I still dont fully understand how a bombing out coastal wont produce sig snow for coast (are we talking rain or a total lack of precip for jersey nyc ct etc)? Im trying to understand but seems like this is a very complicared system.

by **Frank_Wx** Sat Mar 11, 2023 12:07 pm

The GEFS look very good for the area. A lot of members favorable tracked the ULL and phased with the southern energy that allowed a deform band to impact the area. Here's the mean 24-hour snowfall.

March 13th-14th 2023 Big Dog Potential - Page 3 Image-thumb-png-76cbfb379c6bc0afdf7af5e710668aaa

by **jmanley32** Sat Mar 11, 2023 12:14 pm

Frank_Wx wrote:The GEFS look very good for the area. A lot of members favorable tracked the ULL and phased with the southern energy that allowed a deform band to impact the area. Here's the mean 24-hour snowfall.

nice! Hope this keeps moving in even better. But dign me up for this at this pt. I like pivotals maps.

by **jmanley32** Sat Mar 11, 2023 12:18 pm

dkodgis wrote:Potential winds suggest generator time

im not really seeing any wind with this for us. Accuwx seems think so but looking at 850mb winds it only buffets cape and coastal mass. Maybe im wrong.

by **heehaw453** Sat Mar 11, 2023 12:20 pm

sroc4 wrote:
Coachgriff wrote:Great analysis! Really interested to see how this one actually plays out in the end. At this point it appears most of NJ is out of the game with daytime highs on Monday near 50 and lows near 40. Hoping the members north and west get a real snow storm!

No way most of Nj is out of anything coach. Pay no attention to your temps

While I agree looking at weather app temps is not advisable it's advisable to look at the lack of CAD out ahead of the system. As I've been saying if this had a 1035 H parked in Quebec, then even w/out the dynamics coastal plain could pick up some decent snow, but now relying on pure dynamics to get that done. It just significantly reduces chances is my thought.

by **sroc4** Sat Mar 11, 2023 12:31 pm

heehaw453 wrote:
sroc4 wrote:
Coachgriff wrote:Great analysis! Really interested to see how this one actually plays out in the end. At this point it appears most of NJ is out of the game with daytime highs on Monday near 50 and lows near 40. Hoping the members north and west get a real snow storm!

No way most of Nj is out of anything coach. Pay no attention to your temps
While I agree looking at weather app temps is not advisable it's advisable to look at the lack of CAD out ahead of the system. As I've been saying if this had a 1035 H parked in Quebec, then even w/out the dynamics coastal plain could pick up some decent snow, but now relying on pure dynamics to get that done. It just significantly reduces chances is my thought.

The comment was more in line with my forecasted temp is this therefore this won’t happen or this will. With the lack of a textbook HP to the N obv location location location, but in no way most of Nj out yet.

by Coachgriff Sat Mar 11, 2023 12:50 pm

I actually use the thermodynamic maps on tropical tidbits…based on what I can currently see the cold air makes it to extreme northwest NJ then retreats. There does appear to be some wrap around effect as the storm passes….obviously this is an evolving system….is there something I should be seeing? I am willing to learn! Please teach!!

by **Frank_Wx** Sat Mar 11, 2023 1:05 pm

The 12z EURO is rolling. It is looking quite impressive so far. Check out the 24-hour trend at 500mb. Looks familiar? I posted a similar map earlier except it was the GFS. So we're seeing the same trend on both models with a more amplified look at 500mb.

March 13th-14th 2023 Big Dog Potential - Page 3 640cc1cb0f820-thumb-png-d4ad42997fda90162e522b5fe0eef497

by **Frank_Wx** Sat Mar 11, 2023 1:07 pm

Woah, the EURO has the same baby low, or 'meso low,' that the GFS had

March 13th-14th 2023 Big Dog Potential - Page 3 Image-thumb-png-8e538fe3d11a6d2379905591a017dc76

by **jmanley32** Sat Mar 11, 2023 1:11 pm

Frank_Wx wrote:Woah, the EURO has the same baby low, or 'meso low,' that the GFS had

how does this bode for nyc area on this particular run what do temps look like i see 32 way noryh. But your excitement tells me ur intrigued. Oh im look fot 0 line right which is well south of nyc.

by **Frank_Wx** Sat Mar 11, 2023 1:11 pm

Even though H5 improved, I don't think we're getting what we need along the coast. It feels pretty disorganized. That could be due to the lack of vertical stacking. The temperatures are not cooling fast enough. By the time they do, the storm is in New England.

by **Frank_Wx** Sat Mar 11, 2023 1:13 pm

Don't get me wrong the storm really blows up and goes through cyclogenesis, but might be too late for us. Long Island though...gotta watch that CCB.

by **Frank_Wx** Sat Mar 11, 2023 1:14 pm

by **Frank_Wx** Sat Mar 11, 2023 1:16 pm

Wow, H5 closed directly over CNJ. All the precip is on the north-northeast side, so literally anyone south of NNJ sees hardly anything from this.

March 13th-14th 2023 Big Dog Potential - Page 3 Ecmwf-det-thumb-jpg-37e81116856d31b0feabe8a0c2f96eee

by **Frank_Wx** Sat Mar 11, 2023 1:17 pm

Thing is we keep seeing this trend favorably. So if 00z's tonight continue this trend it will put NYC Metro into significant snowfall. Not sure we'll get to Godzilla territory because of temperatures, but let's see...

by **nutleyblizzard** Sat Mar 11, 2023 1:32 pm

Very intriguing indeed with all the models starting to show a double barrel system. With the ULL digging more with each ensuing run, I wonder it’s the models way of telling us that we’re precariously close to a much bigger event with the western low becoming the dominate one with just a little bit more dig by the ULL.

by **jmanley32** Sat Mar 11, 2023 1:36 pm

Frank_Wx wrote:Thing is we keep seeing this trend favorably. So if 00z's tonight continue this trend it will put NYC Metro into significant snowfall. Not sure we'll get to Godzilla territory because of temperatures, but let's see...

ill be totally fine with that if i can get 6 or even a bit more id be happy. 3 to 6 still ok anythimg less ehh. Hoping these trends continue. Hopefully this doesnt wobble back often we see a in between end result. But thats ususllu in nsm sr territory.

by **heehaw453** Sat Mar 11, 2023 1:39 pm

12Z Euro
It's disorganized and unconsolidated at 850 mid-levels. If it consolidated it'd be interesting. You want this thing to start rapid intensification as it moves up and potentially stall or occlude. There's not a lot of time for dilly dally at this latitude. Not impossible for that to happen, but models will sniff it out next 24 hours IMO if there's a chance.

March 13th-14th 2023 Big Dog Potential - Page 3 Euro133

by **jmanley32** Sat Mar 11, 2023 1:44 pm

heehaw453 wrote:12Z Euro
It's disorganized and unconsolidated at 850 mid-levels. If it consolidated it'd be interesting. You want this thing to start rapid intensification as it moves up and potentially stall or occlude. There's not a lot of time for dilly dally at this latitude. Not impossible for that to happen, but models will sniff it out next 24 hours IMO if there's a chance.

i would have to agree sunday eve puts us badically 24 hrs from game time. Lets hope the trens frank pointed put as well as u go in right direction. Often in past years anyways the sr has surprised for the better. Any euro snow map? On mobile kinda hard navigate pivotal

by **heehaw453** Sat Mar 11, 2023 2:01 pm

Another point. Models have taken the ULL into central/southern NJ at 12Z. I doubt it when all is said and done. They failed miserably on the last ULL placement putting it too far south 2-3 days before verification. That was with a big 50/50 and block. The other more significant thing is this s/w came ashore in central Oregon. I like s/w's that come ashore in San Francisco because they tend to exit at the latitude where they enter. I won't be shocked if that ULL corrects further north and the further north that ULL exits the worse snow chances become.

by **hyde345** Sat Mar 11, 2023 2:05 pm

This is 10:1 so likely not accurate but that is all I can get on Pivotal.

March 13th-14th 2023 Big Dog Potential - Page 3 Sn10_a16

by **jmanley32** Sat Mar 11, 2023 2:32 pm

hyde345 wrote:This is 10:1 so likely not accurate but that is all I can get on Pivotal.

similar to gfs. Still leaves some hope for noryh nj nyc and well nw go get crushed. That 10.4 in westchester is literally 9 miles north of me 287 area.

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