March 24-25 Winter Storm Threat

[WeatherX]

It will be quite the feat, if this arrangement can't produce at the end of March. But then again, we've seen some amazing things the past few years...

 

[MJO812]

A tight precip shielf is possible with this upcoming storm due to the confluence to our north. Looks like NYC is on the northern fringes of the precip shield on the Euro control.

[earthlight]

The GFS trended towards the Euro aloft at 06z which is not the greatest thing to see. The handling of the vort max from the Plains through the TN Valley is where the mesoscale and global models differ at this point, so we should have things sorted out within 24 hours I would think...at least in that regard. We will still have some uncertainties with the compressed height field to our north.

Without putting too much stock into the 06z GFS...having the Euro remain far south and not make any marked improvements at 00z is disconcerting. That's about all you can say at this point...it will be interesting to see the trends this afternoon.

[MJO812]

Upton

"The eventual outcome will depend upon several key
details...including the positioning of the upper low across the
Canadian Maritimes and how much...or little...it allows ridging to
amplify out ahead of the approaching shortwave...as well as how
quickly the upper wave closes off across the central and eastern
Continental U.S.. essentially...if the Canadian low...and any shortwave
rotating around it...end up farther northeast...the wave pattern
approaching from the west will have a better chance to
amplify...likely leading to surface cyclogenesis closer to the coast...
farther north and more precipitation for the area.


While there has been some trend in the model guidance and ensemble
solutions towards less influence from the upper low and more
amplification with the approaching wave...did not up probability of precipitation much more
than previous forecast...due to the consistency of the European model (ecmwf) and
continued uncertainty. As for p-type...partial thicknesses generally
support snow. Kept the event as mostly snow across the area...but
continued the previous forecast of mixing with a little rain across
southern areas primarily during the daytime. "

[Zelocita Weather]

Being this seems EXTREMELY SIMILAR to the March 8th event in many ways....the EURO was consistently the furthest south of the models which did not give PHL any precip let alone bury Boston. THe EURO eventually came north to support for the most past the other further north/amplified models. Wondering if EURO has trouble in these types of set-ups. GGEM has been rock solid consistent and it is LATE MARCH with above normal water temps.

 

Was dissapointing to see 6z GFS move S/E less amplified, but we will see, for now I am cautiosly optimistic from what I am seeing.

[ag3]

Being this seems EXTREMELY SIMILAR to the March 8th event in many ways....the EURO was consistently the furthest south of the models which did not give PHL any precip let alone bury Boston. THe EURO eventually came north to support for the most past the other further north/amplified models. Wondering if EURO has trouble in these types of set-ups. GGEM has been rock solid consistent and it is LATE MARCH with above normal water temps.

Was dissapointing to see 6z GFS move S/E less amplified, but we will see, for now I am cautiosly optimistic from what I am seeing.

Water temps are not above average at all.

[ag3]

Being this seems EXTREMELY SIMILAR to the March 8th event in many ways....the EURO was consistently the furthest south of the models which did not give PHL any precip let alone bury Boston. THe EURO eventually came north to support for the most past the other further north/amplified models. Wondering if EURO has trouble in these types of set-ups. GGEM has been rock solid consistent and it is LATE MARCH with above normal water temps.

Was dissapointing to see 6z GFS move S/E less amplified, but we will see, for now I am cautiosly optimistic from what I am seeing.

Water temps are not above average at all.

[jm1220]

The GFS trended towards the Euro aloft at 06z which is not the greatest thing to see. The handling of the vort max from the Plains through the TN Valley is where the mesoscale and global models differ at this point, so we should have things sorted out within 24 hours I would think...at least in that regard. We will still have some uncertainties with the compressed height field to our north.

Without putting too much stock into the 06z GFS...having the Euro remain far south and not make any marked improvements at 00z is disconcerting. That's about all you can say at this point...it will be interesting to see the trends this afternoon.

Agree-I don't think it takes that huge a shift to bring meaningful snow up here, I would want to see the shift soon. And the storm cutting off too soon hopefully doesn't happen either-a sheared out, weak storm won't do much outside of high elevations.

[jm1220]

Being this seems EXTREMELY SIMILAR to the March 8th event in many ways....the EURO was consistently the furthest south of the models which did not give PHL any precip let alone bury Boston. THe EURO eventually came north to support for the most past the other further north/amplified models. Wondering if EURO has trouble in these types of set-ups. GGEM has been rock solid consistent and it is LATE MARCH with above normal water temps.

 

Was dissapointing to see 6z GFS move S/E less amplified, but we will see, for now I am cautiosly optimistic from what I am seeing.

The main storm on 3/8 barely brushed us and hit to the south of us primarily. What caused New England to get the heavy snow and for the re-intensification over our area was another shortwave which came in behind the main low and a strong easterly jet which developed around another wave, which shot a band of heavy snow west on that jet. That doesn't look likely this time, so we need the main low to be further north than that one was.

[wolfsheepsheadbay]

I don't see too many similarities to March 8th. March 8th was about the timing of a phase as a vort rounded the base of a trough in the eastern conus. The coastal, there, didn't have a sharp cutoff, it just swung and missed for this area, because the phase happened too late. This system is really just about the timing of the main vort in the midwest and there being enough separation with the PV to allow it to come up the coast. With this system, there is a much better chance of a sharp precip cutoff. If anything, this resembles those crazy Feb 2010 snow storms with the cutoff by Staten Island. We might be looking at that sort of scenario this time around.

[Weathergun]

I agree with earthlight. We need more than the Nam, Cmc, and Sref to be on board.

[bluewave]

The one thing that is giving me some hope that this still could come north in later model runs is that

that the storm will be happening beyond the peak of the -AO as it's recovering. The suppression

on 2-6-10 and with the first March 8th low was right as the AO was bottoming with maximum 

blocking. It's no guarantee, but it's something to watch in the coming days.

 

 

2010  2  5 -4.7062010  2  6 -5.2052010  2  7 -5.0052010  2  8 -4.7342010  2  9 -4.459

 

[jjvesnow]

SREF's look like they held.  Still a nice hit up here. 

[IsentropicLift]

I apologize if this was already mentioned but I haven't seen it, the 6z GEFS ensemble mean was quite suppressed. Keeps the 0.50"+ line mostly south of the area around southern Monmouth County. All of northern NJ, NYC, Long Island and most interests in the far northern burbs are in the 0.25"-0.50" area. The coastal on the mean tracks from off the NC coast at hr 72 to southwest of the benchmark at hr 78 to southeast of the benchmark by hour 84.

 

Looking at the individual members (in terms of snowfall only not QPF) there were 2 major hits, one moderate hit, and 6 small events, including the mean. This is compared to 00z which had 2 major hits, 6 moderate hits and 2 smaller hits (including the mean)

 

00z had only 2 complete misses (in terms of snowfall only, not QPF) while 06z had 4 or 5 complete misses for the city.

[earthlight]

The SREF mean shifted pretty far south with the MSLP at 72 hours. Not anything to get overly concerned about since they still show a good amount of precipitation, but something to keep in mind. They were very amped up at 03z. 

[IsentropicLift]

SREF's look like they held.  Still a nice hit up here. 

They are significantly drier. This run is 0.50"+ for everyone while the 03z run had the 0.75"+ line touching the SW corner of the city.

[IsentropicLift]

I think we'll continue to see a shift today towards a less amplified solution. The 00z Canadian ensemble mean was way, way, way southeast of the GGEM last night. They barely get the area into the 0.50"+ contour, more like 0.25"+. Seeing the SREF mean shift well southeast isn't a good sign. I think it's becoming clearer that this won't be a major event.

[PB GFI]

I never bought the JMA blockbuster of 1.5 inches nor did I buy the Euros semi shunt from 2 days ago. I have always believed in the end the confluence will end up further north allowing the city on south to hang in the .50 to .75 range.

I think that's a great look for late march and would sign for it now.

This prob doesn't get into New England like march 8 th system did . That system had a secondary redevelopment east of the BM

This will prob come to SNJ then head ENE and limit the northern extent of the precip I disregard the NAM as I always do. And that usually works out well in the end.

[MJO812]

SREF members

[earthlight]

Here's the SREF total precipitation for those arguing that it isn't drier...

 

03z: http://www.meteo.psu.edu/~fxg1/SREF21PCNTOTNE_3z/f87.gif

 

09z: http://www.meteo.psu.edu/~fxg1/SREF21PCNTOTNE_9z/f87.gif

 

It doesn't make a world of difference..the mean still signals a big hit. 

[wolfsheepsheadbay]

SREFs were awesome. .75 for all. .5 and still going with deform at 87. Better than 3z in just about every way.

[MJO812]

SREFs were awesome. .75 for all.

 

.50 + at hour 87 and more to go. Less than 3z but still good.

[earthlight]

The NAM is separating the lead vort max now over the Western US at 33 hours...a bit of a nudge towards the Euro in that regard. It's also slightly less amplified out ahead of it. 

[IsentropicLift]

At hr 36 on the 12z NAM the wave is significantly de-amplified as compared to 6z, but it might just be slower.

[IsentropicLift]

Hr 42 it's closed off at 500mb but heights are quite a bit lower out ahead of it. The wave is flatter. Just based off the changes aloft, I think this run will shift southeast with the coastal in the end, hope I'm wrong.

 

By hour 48 it's amplifying but the base of the trough is a bit flatter.

[MJO812]

Hr 42 it's closed off at 500mb but heights are quite a bit lower out ahead of it. The wave is flatter.

 

This will most likely end up southeast of the 6z run. The question how much though.

[earthlight]

Marked changes on the NAM so far...its this fickle little vort max that seems to be lagging behind the main trough base at 42 hours. This is a change that was noted on the GFS at 06z as well. The vort max is not as consolidated early on (24-36 hr) so I suppose we will have to carefully watch the hi-res models and the HRRR at 500mb over the next 12 hours to see if this is legitimate. The trend towards the Euro occurs when this closed 540dm height shifts southeastward and almost becomes a gyre of sorts by the time it gets to the TN Valley. You then get a plethora of problems including a deamplfying height field ahead of it and much less impressive potential for dynamics. It is a fine line we are walking between the potential for a bomb and a generally flat suppressed solution that goes through a shortwave grinder when it passes under the ULL over New England by Day 4.

 

I suppose there is room for adjustment but this is undoubtedly a bit of a nudge to the Euro's handling of the main players in this broad trough out west with multiple perturbations. With that in mind any forecaster would be inclined to weight the ECMWF products more heavily into their forecast given the ability of that model to discern individual nuances like no other model can seem to handle. 

 

 

 

 

[IsentropicLift]

This will most likely end up southeast of the 6z run. The question how much though.

Closing off again and amplifying some more at hr 51 but the height field out ahead is quite a bit more suppressed than previous runs.

[jm1220]

The NAM is usually too overamplified late in its range. Canadian was probably wrong too given how much its ensembles disagreed with it. We really need to see a north trend soon in other guidance for us to have a shot.

[MJO812]

The NAM is usually too overamplified late in its range. Canadian was probably wrong too given how much its ensembles disagreed with it. We really need to see a north trend soon in other guidance for us to have a shot.

 

The ensembles have been southeast of the op for several runs and yet the GGEM still hasn't followed them.