Feb 8th-9th Potential Blizzard

[phil882]

Hard to call. Still a lot of sensitivity to timing of the northern stream phase and how moist DMC continues to develop the southern low. The NAM races that southern low to the N pretty fast and that is mostly why it takes such a westward track. The NAM would definitely represent the extreme solution. The 00z ECMWF Ens actually strikes a relatively nice balance from what I have seen in current observations and modeling. I think a more realistic reasoning for a farther W solution would be if the northern stream digs/deepens more and slows down...a possible solution. Giving probabilities though, there is a far greater chance, IMHO, that this would wrap up tightly along the coast than take an eastward track. I do think the NAM has a low probability of verifying. 

 

Really agree with this analysis. The NAM is the westward outlier, but thats primarily because it still mainly has the northern stream driving the phasing, which shoots the southern stream s/w nearly due north since its captured by the circulation of the northern stream s/w. 

[OceanStWx]

 

CCB looking pretty good from the 06z GEFS, even with it being farther east. I hope we can hold onto that signal.

[SR Airglow]

Bloomberg just made a press confrence in the city and said 4-6" for NYC, not sure where he is getting that, I think pretty much every model at this point is 8"+ for NYC? Suprised, since he should be commincating with Upton which is calling for much more.

 

-skisheep

[wxsniss]

the earlier-phase-then-scoot-east trend on 6z-12z Nam/Gfs has me just a touch uneasy... obviously a nightmare forecast for NYC

 

bufkit for 12z Nam:

klwm 38.6"

kbos 37.1"

korh 28.6"

kcon 25.9"

kmht 25.7"

khfd 24.9"

kpym 12.4"

 

kewr 27.3"

[SnowGoose69]

Bloomberg just made a press confrence in the city and said 4-6" for NYC, not sure where he is getting that, I think pretty much every model at this point is 8"+ for NYC? Suprised, since he should be commincating with Upton which is calling for much more.

 

-skisheep

 

Maybe a bit too low, I was going 4-8 there, may push it to 5-10 or 7-12 now, still not confident enough the CCB really cranks there.

[CoastalWx]

There is not doubt the southern stream is more amplified than the models had been projecting. However, I do want to throw caution in the wind. The importance of BOTH the northern stream shortwave and the southern stream shortwave can't be overstated. My concern is that the southern stream shortwave continues to become more and more dominant until its driving the phase interaction. This is important to think about from a vorticity perspective, since the dominant vorticity maxima will tend to drive the motion and timing of the phasing. A stronger southern stream s/w and a weaker northern stream s/w might lead to a more amplified (and lower SLP) cyclone, but it also might mean it bombs further offshore. For the further westward tracks to verify (and for all of the NE to get blitzed with snow rather than merely E MA/NH and Maine) we also need the northern stream to continue to amplify in step with the southern stream impulse. Thats what happened in the Boxing Day 2010 blizzard, the northern stream drove the interaction with the southern stream s/w. Even though the southern stream s/w vorticity was under-forecasted, so was the northern stream s/w. That's what ultimately lead to a much further west solution with a rapidly deepening cyclone. 

 

 

Really agree with this analysis. The NAM is the westward outlier, but thats primarily because it still mainly has the northern stream driving the phasing, which shoots the southern stream s/w nearly due north since its captured by the circulation of the northern stream s/w. 

 

Solid posts and agree. Look at all the types of tracks you can have by treaking various s/w's...this is the delicate tango we have to do...but I think they are mastering it.

[40/70 Benchmark]

the earlier-phase-then-scoot-east trend on 6z-12z Nam/Gfs has me just a touch uneasy... obviously a nightmare forecast for NYC

 

bufkit for 12z Nam:

klwm 38.6"

kbos 37.1"

korh 28.6"

kcon 25.9"

kmht 25.7"

khfd 24.9"

kpym 12.4"

 

kewr 27.3"

I have never, ever seen such emphatic lust being spit out from models at such a close range...I mean, this is just pornographically filthy.

[WeatherEmperor]

So I would presume that the almighty Euro will have final say within a couple hours?  And that that will be the basis for all decisions regarding watches / warnings?

[Clinch Leatherwood]

Hard to call. Still a lot of sensitivity to timing of the northern stream phase and how moist DMC continues to develop the southern low. The NAM races that southern low to the N pretty fast and that is mostly why it takes such a westward track. The NAM would definitely represent the extreme solution. The 00z ECMWF Ens actually strikes a relatively nice balance from what I have seen in current observations and modeling. I think a more realistic reasoning for a farther W solution would be if the northern stream digs/deepens more and slows down...a possible solution. Giving probabilities though, there is a far greater chance, IMHO, that this would wrap up tightly along the coast than take an eastward track. I do think the NAM has a low probability of verifying. 

 

Great stuff.

 

Would you expect the Euro to be able to pick up on these finer details? 

[baroclinic_instability]

Really agree with this analysis. The NAM is the westward outlier, but thats primarily because it still mainly has the northern stream driving the phasing, which shoots the southern stream s/w nearly due north since its captured by the circulation of the northern stream s/w. 

Yeah it is really all dependent upon exactly when the two anomalies become phase locked. It may be worth monitoring the Rapid Refresh for dprog/dt with respect to the northern stream wave. The 12z GFS has trended slower and farther W with the northern stream compared to 00z early in the run and is actually farther W than the 00z ECMWF w.r.t. the upper low. Interesting to see if the ECMWF suggests that when it runs here shortly. 

[SnowGoose69]

I have never, ever seen such emphatic lust being spit out from models at such a close range...I mean, this is just pornographically filthy.

 

I think before the 2/6/10 storm in BWI/DC the NAM and GFS were both showing 30 inch amounts 24-36 hours out, in that case it turned out more or less correct.

[40/70 Benchmark]

This is our "White Juan".....happy valentine's day...get nude.

[snowman21]

Bloomberg just made a press confrence in the city and said 4-6" for NYC, not sure where he is getting that, I think pretty much every model at this point is 8"+ for NYC? Suprised, since he should be commincating with Upton which is calling for much more.

 

-skisheep

I don't think Upton has much more than that. NWS has nothing for tomorrow since it's going to be mainly rain, and then the changeover to snow doesn't happen until 9 PM. After that they have 4-8 inches and then mostly sunny by Sat. afternoon, so not a huge deal.

[ORH_wxman]

GGEM pretty much looks just like the RGEM...BM track.

[SnowGoose69]

This is our "White Juan".....happy valentine's day...get nude.

 

More like "Son of Sandy" although up that way you guys didn't quite take it on the chin as badly.

[baroclinic_instability]

Great stuff.

 

Would you expect the Euro to be able to pick up on these finer details? 

Good question. In theory it should be able to, but these models are merely computer code...and you would be surprised what they simulate sometimes. Even the ECMWF can have huge hiccups with the highly non-linear events. 

[ksstormhunter]

_{Upadated my TrendCast output with some newer data, also added more cities in the MA areas.  Boston area showing some impressive snowfall rate potential of 2.1 to 2.4" per hour from 09/06Z ot 09/11Z, which in that time frame could get almost a foot of snow in that period.}

 

_{MA Output:  http://smartwxmodel.net/MA.htm}

[40/70 Benchmark]

I think before the 2/6/10 storm in BWI/DC the NAM and GFS were both showing 30 inch amounts 24-36 hours out, in that case it turned out more or less correct.

I meant for us......even so, That NAM Bufkit is spewing forth about 40" here lol

[SR Airglow]

I don't think Upton has much more than that. NWS has nothing for tomorrow since it's going to be mainly rain, and then the changeover to snow doesn't happen until 9 PM. After that they have 4-8 inches and then mostly sunny by Sat. afternoon, so not a huge deal.

They have 6-10" in their watch for the city, 60% more. 4-6" is nice but no big deal, 6-10" for the city is a large snowstorm.

 

Also, mainly rain for the city tomorrow? EURO and GFS appear to be all snow or close to it. Up here would be suprised if it's mainly rain, we might change over briefly but the trend at 6z and 12z has been colder...

 

-skisheep

[weatherbob]

the earlier-phase-then-scoot-east trend on 6z-12z Nam/Gfs has me just a touch uneasy... obviously a nightmare forecast for NYC

 

bufkit for 12z Nam:

klwm 38.6"

kbos 37.1"

korh 28.6"

kcon 25.9"

kmht 25.7"

khfd 24.9"

kpym 12.4"

 

kewr 27.3"

What about PVD?

[Clinch Leatherwood]

Good question. In theory it should be able to, but these models are merely computer code...and you would be surprised what they simulate sometimes. Even the ECMWF can have huge hiccups with the highly non-linear events. 

 

Seems these issues are most common with systems right on the coast that are explosively developing.  We've seen it a couple of times where even in the very short range models could not get a handle on the westward nature of an event...1/00 being an example where it tucked along the coast following the RUC or whatever it was called at that time which handled the convection the best.

[Ginx snewx]

Ginxy

1) Happy Birthday

2) Historic - can we use that yet?

Top 5 for Boston? Top 10 for ORH?

textbook Thanks its Ians tomorrow he should come home. 2-3 feet

[phil882]

Good question. In theory it should be able to, but these models are merely computer code...and you would be surprised what they simulate sometimes. Even the ECMWF can have huge hiccups with the highly non-linear events. 

 

Yes! In fact the higher resolution you go, the more likely you will create spurious waves that in reality don't exist in the atmosphere. Models as a whole poorly handle the smaller scale wave perturbations in the atmosphere. In fact, in order to avoid the propagating errors that are created by some of these smaller scale waves, most of the models are diffused to some degree in the few few time steps to dampen out these poorly handled waves. Of course the flip coin of this is that you also are probably diffusing waves that are important in these non-linear diabatic driven processes (convection for one) that now don't exist in the numerical simulation. Its a delicate balancing game. Generally the models preform well when convection isn't a major contributing factor towards wave amplification. Obvious this will not be one of those cases, and that's partially why there is still a greater than normal amount of uncertainty. 

[Dsnowx53]

Maybe a bit too low, I was going 4-8 there, may push it to 5-10 or 7-12 now, still not confident enough the CCB really cranks there.

 

 

I guess you're waiting for the 12z Euro to go upwards? I think there's a 50% chance NYC sees > 12", honestly. It still looks like all of the other globals are trending towards the Euro. 

[Typhoon Tip]

JESUS CHRIST!   

 

I have never seen these kind of wind numbers while in conjunction with this kind of QPF in pure snow on the FRH grid in my life and I have been looking at them for over 15 year!!!  There are the 12z NAM numbers for BOS (Logan) 

 

36037999163 07120 150637 35999594 42096978746 23519 970348 39979297 48091947412 01421 940152 34939092 54039925305 00918 010143 26928691 60014886312 -1320 123529 22908589

 

Assuming this were to verify....

close to 20" in just that 9-12 hour period between 36 and 48 hours alone, and you still got over .5" in liq equiv yet to come.  Winds, sustained in mid boundary layer at 48 and 52 knots!!!!   Those are house rocker gusts people, and with that much snow in air and on ground with temps below freezing, that's going to be many hours of near white conditions.   The last 60 digits on the right hand side are the T1, T3, and T5 temperatures levels, which correspond to the 980, 900 and 800 mb levels, from left to right.  i.e., at 42 hours, 97, 92, 97 = -3C, -8C and -3C at those respective levels.  Every row/time interval above is below freezing at all levels through the entire duration of the event. 

 

These are hands down not exaggerated, epic and life threatening numbers without a doubt!  If you are out on roads when this begins to escalate you get your arse off the road and to a safe location.  52 knots (60mph) sustained mid BL flow in a CCB channel will incur gusts nearly to that strength (that standard thermal inversion doesn't apply in a static column of the CCB head - so limited/no protection) closer to the surface.  That could actually mean flying debris amid choking snowfall rates.   I don't see how that can be interpreted another way.   In fact, it would not shock me if the severe thunderstorm warning boxes are triggered around the 52 knot interval, above.   We sometimes see that in hurricanes...   Mind you, this for I-95 and points east.  Tough sell as to what kind of bigger gust materialize in the interior, but 45mph regular should be an easy assumption - blizzard conditions.

 

Obviously, this a very extreme solution.  It is rare ... perhaps approaching exceptionally rare.  Words like historic ... certainly histrionic, epic and unfortunately all apropos and need to be heeded this time.  One would have trouble writing fiction with these types of values because it's difficult to really get one's mind around what a sustained 52 knot boundary layer flow with snow falling 2-3" per hour really means - and these are still regional values; if there is a meso band in there, double that!  

 

Well, needless to say... I am excited.  

[wxsniss]

What about PVD?

 

kpvd 25.7"

[HoarfrostHubb]

Tippy ---- decaf...lol

(jk, that is interesting stuff)

[Mr. Windcredible!]

There is not doubt the southern stream is more amplified than the models had been projecting. However, I do want to throw caution in the wind. The importance of BOTH the northern stream shortwave and the southern stream shortwave can't be overstated. My concern is that the southern stream shortwave continues to become more and more dominant until its driving the phase interaction. This is important to think about from a vorticity perspective, since the dominant vorticity maxima will tend to drive the motion and timing of the phasing. A stronger southern stream s/w and a weaker northern stream s/w might lead to a more amplified (and lower SLP) cyclone, but it also might mean it bombs further offshore. For the further westward tracks to verify (and for all of the NE to get blitzed with snow rather than merely E MA/NH and Maine) we also need the northern stream to continue to amplify in step with the southern stream impulse. Thats what happened in the Boxing Day 2010 blizzard, the northern stream drove the interaction with the southern stream s/w. Even though the southern stream s/w vorticity was under-forecasted, so was the northern stream s/w. That's what ultimately lead to a much further west solution with a rapidly deepening cyclone. 

 

What did the Euro ensembles show last night? Bit east of the op?

[Clinch Leatherwood]

Yes! In fact the higher resolution you go, the more likely you will create spurious waves that in reality don't exist in the atmosphere. Models as a whole poorly handle the smaller scale wave perturbations in the atmosphere. In fact, in order to avoid the propagating errors that are created by some of these smaller scale waves, most of the models are diffused to some degree in the few few time steps to dampen out these poorly handled waves. Of course the flip coin of this is that you also are probably diffusing waves that are important in these non-linear diabatic driven processes (convection for one) that now don't exist in the numerical simulation. Its a delicate balancing game. Generally the models preform well when convection isn't a major contributing factor towards wave amplification. Obvious this will not be one of those cases, and that's partially why there is still a greater than normal amount of uncertainty. 

 

Perfect this is what I was driving at.   To me it looks like the NAM and to an extent the RGEM through 24 hours picked up on the more rapid development that is also apparently a little north of earlier runs.  But from there it could just be a cascading error...or not.

RAP may play a more useful role too.   As of now no real deviation from the consensus along the Carolina coast later today.

[Clinch Leatherwood]

GEFS are in.