April 1st-2nd Nor'Easter Potential

[HM]

What me and a few guys in the office were noticing is how long the wavelengths are and what the "usual" late season storm looks like. The temperatures are not nearly as cold as some of the greats in April but the jet stream is up there with any mid winter cyclone. This is truly the NAO pattern shift storm as the anomaly gets absorbed into the PNA ridge. A wind driven heavy wet snow can be a disaster unfortunately.

[A-L-E-X]

What me and a few guys in the office were noticing is how long the wavelengths are and what the "usual" late season storm looks like. The temperatures are not nearly as cold as some of the greats in April but the jet stream is up there with any mid winter cyclone. This is truly the NAO pattern shift storm as the anomaly gets absorbed into the PNA ridge. A wind driven heavy wet snow can be a disaster unfortunately.

HM you called this from two weeks out.... this is the monster that changes the pattern. Looks like if this is to be a snow event for the coast, it's going to have to drag down cold air and be a night time event.... at least that second part looks very likely.

[green tube]

TWC is calling for 6-12 inches in the big cities. Wow,they are usually conservative.

http://www.weather.c...torm_2011-03-29

they say it's possible. they're not "calling for."

[A-L-E-X]

What puzzles me is why would the Euro be a rain track for coastal areas (this is what Upton said in their text AFD).... a track 100 miles south of Montauk should be perfect for snow.

[Alpha5]

Just took a look at the Euro Ensembles....

QPF:

NW of 95: .75-1.0" QPF

SE of 95: 1.0-1.25" QPF

Temps:

Marginal for LI at the start, but as temps crash and thickness falls everyone goes over it looks like the storm really bombs out towards the BM

Spag Plots:

a TON of heavy hitters right at the BM, just like the OP euro....nearly all ensembles are within 50 miles of the OP euro and many of them sub 980

this one is real folks

[HM]

HM you called this from two weeks out.... this is the monster that changes the pattern. Looks like if this is to be a snow event for the coast, it's going to have to drag down cold air and be a night time event.... at least that second part looks very likely.

The cold air will be pretty marginal and may not cut it in a typical WAA setup this time of year. However, the dynamics with this one are being modeled to be very extreme...for any season. It won't matter what your h85 temp is because they will collapse rapidly when that deformation band gets going.

I would say 0.2-0.4 of that QPF on the ECMWF is rain between 06z-12z and the rest is snow in E PA, NJ and NYC. Most likely a ratio that gradually grows too in the morning from a terrible 5-8:1 ratio to a 10:1, especially NW.

[bmc10]

The cold air will be pretty marginal and may not cut it in a typical WAA setup this time of year. However, the dynamics with this one are being modeled to be very extreme...for any season. It won't matter what your h85 temp is because they will collapse rapidly when that deformation band gets going.

I would say 0.2-0.4 of that QPF on the ECMWF is rain between 06z-12z and the rest is snow in E PA, NJ and NYC. Most likely a ratio that gradually grows too in the morning from a terrible 5-8:1 ratio to a 10:1, especially NW.

So do you think the odds of seeing a 3+ snowfall in NYC and a 6+ N and W are rapidly increasing?

[Dsnowx53]

What me and a few guys in the office were noticing is how long the wavelengths are and what the "usual" late season storm looks like. The temperatures are not nearly as cold as some of the greats in April but the jet stream is up there with any mid winter cyclone. This is truly the NAO pattern shift storm as the anomaly gets absorbed into the PNA ridge. A wind driven heavy wet snow can be a disaster unfortunately.

Do you mean that the wavelengths with this potential event are a lot longer than they "normally" would be this time of year? Perhaps part of that is because of the kicker, aka the 3rd s/w...?

[A-L-E-X]

The cold air will be pretty marginal and may not cut it in a typical WAA setup this time of year. However, the dynamics with this one are being modeled to be very extreme...for any season. It won't matter what your h85 temp is because they will collapse rapidly when that deformation band gets going.

I would say 0.2-0.4 of that QPF on the ECMWF is rain between 06z-12z and the rest is snow in E PA, NJ and NYC. Most likely a ratio that gradually grows too in the morning from a terrible 5-8:1 ratio to a 10:1, especially NW.

Im trying to come up with a list of analogs.... obviously 4/82 is out, because that was such a cold storm..... so we're left with 4/96, 4/97, and 4/03. This looks like a 4/97 but with the heaviest precip maybe 100 miles further south (good for us)..... 4/96 would be the number 2 analog (but that was colder than this).... 4/03 was an awesome storm but this looks like it will be MUCH more dynamic than that (I don't remember any heavy winds with 4/03.)

[HM]

So do you think the odds of seeing a 3+ snowfall in NYC and a 6+ N and W are rapidly increasing?

As long as the outcome is just like today's data, it most certainly has increased. As others have pointed out, it is bad enough getting everything together in Dec-Feb. It has to be perfect this time of year...but this is the year to do that.

[HM]

Do you mean that the wavelengths with this potential event are a lot longer than they "normally" would be this time of year? Perhaps part of that is because of the kicker, aka the 3rd s/w...?

Well, I don't have the hard facts on hand but I know from looking through the Kocin book that usually there are two long wave features on both coasts with a ridge in between. As you know, this is typical of spring. However, this setup is just two waves...1 being the western ridge and the second being the giant trough in the East. To see this visual, just go to about 72hrs on the models. That l/wv setup is like January!

[Snow_Miser]

New HWO from Upton

DAY ONE...THIS AFTERNOON AND TONIGHT.

HAZARDOUS WEATHER IS NOT EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.

LOW PRESSURE WILL EMERGE FROM THE MID-ATLANTIC COAST THURSDAY

NIGHT AND DEEPEN RAPIDLY AS IT TRACKS NORTHEASTWARD OVER THE

ATLANTIC ON FRIDAY. DEPENDING ON THE EXACT TRACK AND INTENSITY OF

THE SYSTEM...THE POTENTIAL EXISTS FOR STRONG WINDS AND HEAVY

PRECIPITATION...INCLUDING ACCUMULATING WET SNOW.

[RU848789]

I think that's an exaggeration. And you don't report a range like 6-9. You report a specific total.

http://www.njfreeway.../07-Apr-03.html

I see a few 7s and 1 or 2 8s, but lots and lots in the 3-6 range.

Got 7.0" from that storm in Metuchen and about 7" in Rahway, where I work. I recall making a summersnowman with my 8-year old son - outfitted him with sunglasses, hat, shorts, sunscreen, umbrella, etc. Melted really fast the next day, though.

Also interesting that New Brunswick got so much more than CPK on 4/6/82: I was a sophomore that year and recall measuring 13" of snow - the 80s sucked for snow and that was the only day RU closed in my 9 years on campus (Feb 83 didn't hit real hard until mid/late afternoon). Had the biggest snowball fight I can ever remember between the Quad dorms and the River dorms, across George Street - and every car that drove by was completely annihilated with snowballs.

[bmc10]

As long as the outcome is just like today's data, it most certainly has increased. As others have pointed out, it is bad enough getting everything together in Dec-Feb. It has to be perfect this time of year...but this is the year to do that.

Yes this certainly has the potential to be another very exciting and dynamic storm. Thanks for your input, I have always valued your opinion. Keep up the good work!

[A-L-E-X]

Got 7.0" from that storm in Metuchen and about 7" in Rahway, where I work. I recall making a summersnowman with my 8-year old son - outfitted him with sunglasses, hat, shorts, sunscreen, umbrella, etc. Melted really fast the next day, though.

Also interesting that New Brunswick got so much more than CPK on 4/6/82: I was a sophomore that year and recall measuring 13" of snow - the 80s sucked for snow and that was the only day RU closed in my 9 years on campus (Feb 83 didn't hit real hard until mid/late afternoon). Had the biggest snowball fight I can ever remember between the Quad dorms and the River dorms, across George Street - and every car that drove by was completely annihilated with snowballs.

Yeah, EWR had 13" in 4/82 also.

[CooL]

gfs not looking to hot, all rain so far

[IsentropicLift]

GFS looks west of 12z and warmer

[ag3]

18z GFS ruins party for coast.

Lol.

[CoastalWx]

Disaster.

[mattinpa]

GFS looks west of 12z and warmer

Let's see if it's still that way at 0z, along with the other models. And the NAM still doesn't agree that there will be the big storm.

[LovintheWhiteFluff]

GFS looks west of 12z and warmer

Looks more like 4mb weaker and on the same track.

[IsentropicLift]

I think were going to continue to see "warm run" "cold run" differences for another day or so before a final track becomes more apparant

[TheTrials]

18z GFS ruins party for coast.

Lol.

ruins it for more than just the coast. This is a much more plausible solution than the snow bombs we have been seeing.

[bmc10]

gfs not looking to hot, all rain so far

Like I said earlier when I commented on the euro run, an earlier phase and cyclogenesis of the low can benefit our area. We need it to happen this way so that we benefit from the CCB and intense dynamics. If the low explodes north of us, we will be more likely to see only moderate precip and warmer temps.

[jconsor]

I looked at the NCEP 20th Century reanalysis for 3 large snowstorms in the late 1800s and early 1900s - Apr 13, 1875; Apr 3, 1915; and Apr 9, 1917. All three fit the typical pattern that you mention with troughs between the West Coast and the Rockies and a ridge in between. This pattern is truly anomalous!

Well, I don't have the hard facts on hand but I know from looking through the Kocin book that usually there are two long wave features on both coasts with a ridge in between. As you know, this is typical of spring. However, this setup is just two waves...1 being the western ridge and the second being the giant trough in the East. To see this visual, just go to about 72hrs on the models. That l/wv setup is like January!

[mattinpa]

I think were going to continue to see "warm run" "cold run" differences for another day or so before a final track becomes more apparant

Agree. And even on this run there could be wap-around snow for the NYC and Philly areas.

[IsentropicLift]

closes off too far past us and wrap around moisture is probably overdone, definitly a step backwards but not a terrible run

[CooL]

Like I said earlier when I commented on the euro run, an earlier phase and cyclogenesis of the low can benefit our area. We need it to happen this way so that we benefit from the CCB and intense dynamics. If the low explodes north of us, we will be more likely to see only moderate precip and warmer temps.

we need an earlier H5 close off, euro had it occurring over nyc, this run is in new england.

[IsentropicLift]

Looks more like 4mb weaker and on the same track.

I was looking at the 850mb temps. They look much warmer at the onset of precip than 12z.

[IsentropicLift]

ruins it for more than just the coast. This is a much more plausible solution than the snow bombs we have been seeing.

It was one run....hardly a trend at this point