jm1220

Again a trend towards an earlier consolidated low, so the CCB cranks in time for us. Exactly what we need.

Double low with one just off NJ means the inverted trough is ruining our airmass here even more and we waste most of the storm with rain while the main low and dynamics take forever to get going. No that's not what we want.

UK is often slightly too warm at the surface. The key is consolidating the offshore low early and turning the flow around to NE to push the warm maritime crap away and make us benefit from crashing heights/dynamics.

If we can get the Euro to show that as well for a couple runs, maybe we're onto something. Trend does seem to be to develop that offshore low sooner which brings colder air in and heavy snow banding.

UKMET back to being hilarious. Has 12" or nearly in NYC and nothing in Hartford/Springfield because of downslope. Boston gets slushy 1-2" at the end. I can't imagine how SNE would melt down from that (there'd be little to melt anyway). I'd pay big bucks to see that.

This is a very complex setup and tiny changes in where/if/when phasing occurs, amplitude of the trough etc can have dramatic effects so we’re not “out” of it until tomorrow night I’d say if it’s not looking favorable. That said the odds are way higher for a major impact in places like the Catskills and Berkshires than us near the coast. We need way more to go right. Expect a washout but if we roll snake eyes somehow it can be a good outcome.

Offshore low cranks sooner, ends the inverted trough garbage and builds a CCB that clips most of us. The heavy amounts will shift around and it’s impossible to know where bands would set up, but that’s what we need to see near the coast to have a shot. GFS is a convoluted mess that hopefully is just the model confused with the setup and not knowing what to emphasize.

If we get wraparound mood snow for a while it likely wouldn't accumulate if it's battling 34-35 degree temps and March sun. We would optimally want it to happen at night, and the low to bomb earlier and form a CCB over us so we get the benefit of heavy rates and cold air from the crashing heights.

Expect rain and be happy if it turns into something more. The inverted trough is ruining it (which causes that low reflection near NJ) like the other runs/models. That needs to go away for the NYC area to see anything other than a washout.

Yes we would definitely want the Euro depiction of it closing off sooner and a little further SW than the GGEM has. The storm really doesn’t go to town until those upper lows close off and heights crash to bring cold air in. The initial precip is really from a frontal boundary of sorts caused by an inverted trough that brings in warm air on the east side of it which is where we start off.

Depends on where that initial inverted trough precip sets up, should be cold enough in the Poconos for it to be snow.

Expect rain from this and if it ends up as something more you’ll be happy. If you’re hoping for/expecting a MECS you’re very likely to get disappointed. Maybe not the worst time to check out Hunter Mountain lol.

I didn't see the outputs on that run but I guess the low consolidates sooner and that inverted trough crap which is where most models produce our QPF from goes away. That's the shot we have for more than just wraparound flakes in NYC. Becoming very clear IMO and has been for a couple days that the places to be for this storm are the Helderbergs/N Catskills, Berkshires and Worcester hills. But the NW parts of our subforum do very well also if we can get that slightly quicker consolidation of the storm.

It's the NAM so I wouldn't be concerned. But what looks likely is that we have this inverted trough feature as the storm comes in that might be spinning up this western low appendage, and it screws people near the coast because that inverted trough brings in 40 degree maritime air on strong easterly wind. Another reason we want this offshore low to develop quickly, so the flow can back around to offshore and dynamics can overcome the crap initial airmass. That inverted trough and the too slow development of the low are the main factors that are ruining it near the coast.

GFS is able to pull it off but we need a pretty substantial SW shift in the developing dynamics and upper low track in the other models to be confident of wintry impact in NYC. I’d give it a 10% chance of an advisory event or greater in the city but can’t be written off yet. Don I’m sure has better stats for what the ensembles show. Expect rain and then be thrilled with a better outcome.

Looks very weird since it chases convection east with one low and the other near the coast. Look at the upper air lows vs what it shows at the surface for dynamics that can kick in for any snow. Multiple lows probably mean just a marginal slop fest.

Another way to look at it-the 700mb low and vertical velocity (lift). Notice how it is well placed for New England because these dynamics get going a little too late for NYC. You want to be just NW of the 700mb low to get into the really good/intense banding. Here's 72hr 78hr-at this point we're probably getting some wraparound snow around the closed/stacked upper low but you can see overall the lift is weakening because the low is stacked. We can see clearly how we want this dynamic happening sooner/SW for our subforum. It's the problem we have all the time with these late developing Miller B type lows. But this is the GGEM outcome, GFS was more favorable. And before 72hr we're too warm in the preceding airmass, and we don't get the benefit of strong lift/dynamics to help overcome it unless you're inland and above probably 500-600ft.

Notice here at 72hrs when the low is SE of Montauk, the direction of the 500mb flow. The low is about to mature but the flow is generally out of the SE. That doesn't really allow a mature CCB/comma head to develop and spread snow well west of the low. We want all this to happen sooner. The focus of the moist feed is into New England. Here by 78hr the 500mb low is closed off and there's a mature CCB with moisture being brought west around the closed low. From here the surface low stacks and starts to weaken since there is no longer a way to evacuate air aloft over top of the low. But see how where it closes off is a great spot for interior New England. We want that 75 miles SSW or so. The crashing upper air heights as you can see there also brings cold air down to the surface.

The upper air system on the GGEM is not matured so there is not a mechanism to spread snow/precip well west of the center. Note on the 500mb chart how the flow is from the SSE mainly near the low, and the closed low is well west of it.

This double low thing will hopefully consolidate into one bigger low sooner. Probably comes from a sloppy phase. But yes, nice improvement.

When did it ever start?

Excellent post but if this (likely) doesn't work out I'm just done. If something happens on 3/20-22 great, but unfortunately the calendar ticking later means more has to go right for anything substantial, and time and again "great pattern" gets ruined by some turd. This is another Nina strikes again situation with the northern stream driven system messing things up, lousy/progressive western ridge placement, etc. Exactly why New England/upstate NY often do perfectly fine in well coupled Nina winters but it gets so much harder from this latitude and south. Albany isn't far below normal for snow and Central Park is sitting at 2.3". With this Albany has a shot at hitting 60"+ on the season (has 41.9 now) while NYC sits at the same pathetic 2.3". My money now is on the too late development vs too early it was seeming yesterday and before.

UKMET buries the Berkshires/Albany area into NW CT. Those have been the places consistently hit hard in the modeling. Near the city on this run we have strong easterly flow and maritime air in the 40s for the beginning of the storm, storm bombs in a lousy place (but further west than GGEM), blah blah blah.

On the 5-10% chance this can pan out, the upside is very high if we can somehow get the low to bomb out 75 miles or so S of Montauk. Those crazy UKMET runs are legit in that very off chance. But the GGEM bombing it out S of Nantucket then tracking it near Cape Cod is way too far east for NYC. We also have the usual problem of strong easterly flow maritime air that has to be overcome as the precip (rain) moves in. So what happens is we get moderate rain for a while in the maritime crap airmass (wet snow inland) that changes to heavy snow over SNE where the late bombing low can work. But the low can't bomb/phase too early because then the low will hug the coast and we get rain from a too far west track. So I'm not encouraged. I'll keep an eye on the next few cycles but if no improvement I'm out.

Hope for SNE on that run? Absolutely. For us near the city/coast? We’re completely screwed because of the low bombing too late and east. We need it to bomb early yet not get yanked due north too early-both processes are linked because the phase that bombs the low also yanks it north. Too late means light/moderate rain here and crushing snow from the Catskills to Boston.