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April 7-8 snow event

PrinceFrederickWx

By PrinceFrederickWx,
in Mid Atlantic

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MillvilleWx

MillvilleWx

Posted
Posted
  On 4/4/2018 at 10:24 AM, showmethesnow said:

This is a somewhat anomalous event so i am not really sure what to believe at this time so I am trying not to prejudge things just because of the time of the year. Pretty much just along for the ride to where the models take us.

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  On 4/4/2018 at 10:21 AM, C.A.P.E. said:

6z GFS still has the low moving along the cold front and getting shunted offshore of the NC coast pretty far south. Still produces a nice swath of snow across the region. 

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There's certainly solid potential with this system. If the baroclinic zone can adjust north with a more defined surface low, then it could be a pretty historic event given the time of year. I truly believe this will come north more, but I don't buy the progressive nature of the NAM. It was different with the handling of the upper low out west. Much stronger than any of the global's, which will cause all sorts of changes downstream. GFS and Euro were close, but the GFS was a bit more progressive and the low in the Pac was weaker and further east. Euro with a stronger low was able to establish more ridging over the Rockies, thus more dig of the shortwave across the Tennessee Valley. Baroclinic zone was a touch further north too. I think the GFS is a bit too progressive here, which is one of its biases in the mid range. I think the Euro may have the right idea, but has been the case so far this year, it's probably overdone on the precip field. We've seen that too often recently. H7 jet streak on the Euro is at 75 knots with the area in the left exit region of the jet. That would certainly be a precip bomb if that verified, but I think it's still overdone. 

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MillvilleWx

MillvilleWx

Posted
Posted
  On 4/4/2018 at 10:45 AM, osfan24 said:

The Euro solution is amazing and an April HECS without a doubt, but again, I'm still waiting on my March 20 HECS that turned into several inches. The Euro is just so awful now that it's hard to ever take it seriously anymore.

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In the case of the setup, I think it's best to use Euro as a gauge in the upper levels and where the surface low is generated. I would ignore the qpf fields until close in. Yeah, they are fun to look at, but I can see the Euro trimming back on the insane precip totals for the system. Now, this could be a pretty solid precip producer, but an 1" of qpf in 6 hrs is off the wall stuff. Even 60% of what the Euro shows would be a solid storm and definitely historic for April. 

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MillvilleWx

MillvilleWx

Posted
Posted

The 6z ICON is actually fairly Euroish in its evolution and even has a very similar timing. It's further north than previous runs as well with a more expansive qpf shield, and more realistic compared to the Euro (Although its still a qpf bomb!). That's a good thing to see as a more progressive disturbance like the GFS and NAM would lay pause to the Euro. I'd actually like to see the ICON take a steadier approach as it's shakier than the Orioles starting lineup with the system so far, so hopefully we start seeing things hone in a bit on the evolving upper air pattern. 

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Bob Chill

Bob Chill

Posted
Posted
  On 4/4/2018 at 11:05 AM, leesburg 04 said:

Heavy heavy snow even if it doesn't accumulate fast is still really cool. I can attest from yesterday's snow here

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Peas in a pod on that one. Yea, midwinter April dreams are fun but if the ground truth is hours of potato missiles with a solid ground whitening...I'll pay the bill and leave a 25% tip. 

Euro just gave us the run that Ji sets as a minimum benchmark but one man's epic disaster is another man's gold mine

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WxUSAF

WxUSAF

Posted
Posted

I like how the GFS is speeding the storm up slightly.  Now 6z has heavy precipitation in the 6z-12z overnight window.  I'm all about maximizing the snowfall during darkness with this setup.  12z Saturday sounding is almost too good to be true.  

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osfan24

osfan24

Posted
Posted
  On 4/4/2018 at 11:45 AM, WxUSAF said:

I like how the GFS is speeding the storm up slightly.  Now 6z has heavy precipitation in the 6z-12z overnight window.  I'm all about maximizing the snowfall during darkness with this setup.  12z Saturday sounding is almost too good to be true.  

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I'll take a combo of GFS early onset and Euro duration and qpf please!

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Bob Chill

Bob Chill

Posted
Posted
  On 4/4/2018 at 11:45 AM, WxUSAF said:

I like how the GFS is speeding the storm up slightly.  Now 6z has heavy precipitation in the 6z-12z overnight window.  I'm all about maximizing the snowfall during darkness with this setup.  12z Saturday sounding is almost too good to be true.  

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Lol...yea. We struggle with wiggle room in the heart of winter but the soundings coming out...for April 7th...have wiggle room. Weird. 

This reminds me of how we scored in feb/Mar 14 and 15. Fresh arctic front presses in and a juiced wave hits right when temps get right. I suppose it's one of the only ways to get it done this late. I have like no experience tracking more than conversational snow in April so I'll just assume the worst and let it ride. 

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WVclimo

WVclimo

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Posted

Went back and read the obs thread from 10/29/2011 this morning.  Rain changed to snow here around daybreak that day.  By 8:00 a.m. snow had accumulated on pavement.  Rates were moderate to heavy all morning and through most of the afternoon.  Temps were right at freezing.  0.80" of liquid fell as snow and yielded a 4" accumulation.  Have to imagine even with heavy snow falling it would be harder to achieve that 5:1 ratio in the day time in April than late October ?

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WxUSAF

WxUSAF

Posted
Posted
  On 4/4/2018 at 12:03 PM, Bob Chill said:

Lol...yea. We struggle with wiggle room in the heart of winter but the soundings coming out...for April 7th...have wiggle room. Weird. 

This reminds me of how we scored in feb/Mar 14 and 15. Fresh arctic front presses in and a juiced wave hits right when temps get right. I suppose it's one of the only ways to get it done this late. I have like no experience tracking more than conversational snow in April so I'll just assume the worst and let it ride. 

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In all honestly, I'd still put the odds of this shifting north until it's a flush hit for Harrisburg, rain for DC, and 1-2" of slush for Hoffman/mappy at >50%.  But hey, we're less than 3 days from go time, so let's see what happens.  

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olafminesaw

olafminesaw

Posted
Posted
  On 4/4/2018 at 12:08 PM, WVclimo said:

Went back and read the obs thread from 10/29/2011 this morning.  Rain changed to snow here around daybreak that day.  By 8:00 a.m. snow had accumulated on pavement.  Rates were moderate to heavy all morning and through most of the afternoon.  Temps were right at freezing.  0.80" of liquid fell as snow and yielded a 4" accumulation.  Have to imagine even with heavy snow falling it would be harder to achieve that 5:1 ratio in the day time in April than late October ?

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We're 2.5 months from the solstice, while the end of October is over 4 months past. Big difference in sun angle.

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BlizzardNole

BlizzardNole

Posted
Posted
  On 4/4/2018 at 12:08 PM, WVclimo said:

Went back and read the obs thread from 10/29/2011 this morning.  Rain changed to snow here around daybreak that day.  By 8:00 a.m. snow had accumulated on pavement.  Rates were moderate to heavy all morning and through most of the afternoon.  Temps were right at freezing.  0.80" of liquid fell as snow and yielded a 4" accumulation.  Have to imagine even with heavy snow falling it would be harder to achieve that 5:1 ratio in the day time in April than late October ?

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Interesting comparison!  I looked at Dulles records to compare the two dates.  How's this for coincidence -- both Oct 29 and April 7 have the exact same average high and low of 64/40.  The low max for Oct 29 was 39 (on your 2011 snow day) and for April 7 it was 42.

Where it differs is sun angle/strength.  Oct 29 is equivalent to mid February, while April 7 is equivalent to Sept 4.  That's a big difference.

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mappy

mappy

Posted
Posted
  On 4/4/2018 at 12:32 PM, North Balti Zen said:

A storm on April 7 ending up further north is certainly a safe bet at any rate. I think we all know this is almost literally chasing a weather unicorn for inside the beltways. I think you could do well though in more scenarios.

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i dont want it. i mean, i will take it, will go play in it, but i dont want it. 

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psuhoffman

psuhoffman

Posted
Posted
  On 4/4/2018 at 4:24 AM, Bob Chill said:

I'll say this...after the last month i've been through...this would mean a lot to me. I'm not trying to be all mushy and stuff but Saturday may be some well needed therapy. 

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If anyone deserves it you do. I know the weather don't give a **** but I'm rooting for you. 

  On 4/4/2018 at 9:26 AM, C.A.P.E. said:

6z NAM *out of range* tracks the low a bit further north. 850s stay warmish for I95 east. Best snow area would be the NW burbs.

Not that I am buying the NAM at range, but this is actually what I expect given the very late date we are dealing with. Heavy wet snow NW of the fall line, with rain/sleet to slop south and east and maybe a coating. GFS will correct quite a bit further NW and the Euro a bit more over the next couple days. I predict PSU will be biting his nails again.

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I'm not worried about south either. But I'm not as sure this ends up shifting way north either. The cold is more legit this time then the last wave. That will matter. It will adjust north just not sure it's to the same degree. We're 72 hours out now. Last time from 72 the axis adjusted from MD to central PA from that range. But the cold was weak sauce and the snow coverage was always narrow. Let's say this adjusts half of that, then D.C. could still hold on with solid snow on the south side of the axis.  Agree it comes north just not sure how much. 

@MillvilleWx

great analysis thanks 

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dallen7908

dallen7908

Posted
Posted
  On 4/4/2018 at 12:08 PM, WVclimo said:

Went back and read the obs thread from 10/29/2011 this morning.  Rain changed to snow here around daybreak that day.  By 8:00 a.m. snow had accumulated on pavement.  Rates were moderate to heavy all morning and through most of the afternoon.  Temps were right at freezing.  0.80" of liquid fell as snow and yielded a 4" accumulation.  Have to imagine even with heavy snow falling it would be harder to achieve that 5:1 ratio in the day time in April than late October ?

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Interesting although off topic:

 

WCAC held their XC championship that day at Lake Fairfax.  Cold rain during girls race (see video of "stream" crossing) followed by snow during boys varsity race. 

Through the finish line and into your bus was the mantra. 

 

https://video.search.yahoo.com/yhs/search?fr=yhs-Lkry-SF01&hsimp=yhs-SF01&hspart=Lkry&p=wcac+2011+cross+country+championship#id=1&vid=1be3eed407dfdd8629cd22c614ba1bea&action=click

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