April 7-8 snow event

[yoda]

5 minutes ago, Eskimo Joe said:

The GFS has a known bias of transitioning too quickly from rain to snow.  The Euro should be given a greater weight in these situations.

Link to this?

[BristowWx]

1 minute ago, Cobalt said:

Never heard of that bias before, but it also could be in this case due to the GFS being farther south than the Euro

I always wonder where these known biases are documented.  The term known biases gets thrown around quite a bit.  

[clskinsfan]

3 minutes ago, BristowWx said:

Most of the fretting is coming from the southern half.  But you knew that.  Winchester looks fine.  But you knew that too.  

It's April man. IF A SINGLE snowflake falls it is pure bonus snow.

[Cobalt]

4 minutes ago, clskinsfan said:

It's April man. IF A SINGLE snowflake falls it is pure bonus snow.

Methinks you have a shot at 75% climo on the year

[BristowWx]

4 minutes ago, clskinsfan said:

It's April man. IF A SINGLE snowflake falls it is pure bonus snow.

I think/hope we can manage a single snowflake out of this.  Even the lowlands.  You should get more than one.  

[Eskimo Joe]

12 minutes ago, Cobalt said:

Never heard of that bias before, but it also could be in this case due to the GFS being farther south than the Euro

@das and @high risk have discussed it before.  Essentially, the GFS is famous for cooling off the mid levels much quicker than other guidance and this complicates the forecast when you're dealing with a rain -> snow situation.  This causes it to over do snow forecasts.

[stormtracker]

19 minutes ago, winterymix said:

GFS blankets much of the Balto-DC corridor with 4-6.

Did you hear? We won WWII

[Maestrobjwa]

1 hour ago, jayyy said:

Lolz at the 18 gfs kuchera jackpot over BAL metro.  

You rang?  (not often I hear my area modeled as a bullseye...so I couldn't resist chiming in, lol) It is gonna be interesting to see how all this shakes out...so what do we think? Euro comes north or south at 0z? Lol

[olafminesaw]

6 minutes ago, Eskimo Joe said:

@das and @high risk have discussed it before.  Essentially, the GFS is famous for cooling off the mid levels much quicker than other guidance and this complicates the forecast when you're dealing with a rain -> snow situation.  This causes it to over do snow forecasts.

The main difference is position of the front though. The GFS has the 850 mb 0 line like 70 miles further south.

[Bob Chill]

IIRC- the gfs has more of a progressive bias than a warm bias. In this case I can see how that type of bias makes it look like a cold bias because it brings in the air colder with this specific system. However, the GFS definitely leans warmer at the surface quite often and when other guidance disagrees  the gfs is usually wrong. Not sure that applies in this case and the temps on the gfs are actually really good. Soundings are like as good or better than 12z. 

I will say the GFS is the steadiest with the progression/track of the low. The fact that 18z pretty much held identical is fairly important. Yea, it moved "southeast" a little but it was a noise type of bump and not meaningful other than still supporting a pretty nice event. Until the GFS burps NW like the euro/nam I think we are still very much in the game. What happens when 0z gfs looks identical again the the euro moves somewhere between it's last 2 runs? 

I personally ignore the nam almost all the time now. I said this last night...gfs/euro blend is the most accurate short/med range guidance the vast majority of the time. I'm kinda expecting the euro to move back a little more in our favor. It's still razor thin and there's still enough lead time for this threat to vaporize for all but the NW tier but I'm actually leaning towards something more than conversational snow for much of the area. Especially 95 and W. SoMD is really tricky. I'll leave that to the proprietary Prince Frederick Model.

 

ETA: ICON moved in the right direction too. Very interesting. The only bleeding was on the euro but the ens painted a better picture. It kinda has that feel that jumping on the 12z euro as a nail in a coffin is going to end up pre-mature. We'll know if I'm right while I'm asleep later.  

[BristowWx]

1 minute ago, Maestrobjwa said:

You rang?  (not often I hear my area modeled as a bullseye...so I couldn't resist chiming in, lol) It is gonna be interesting to see how all this shakes out...so what do we think? Euro comes north or south at 0z? Lol

My guess is that it does change to snow NW to SE but slower than the best scenario model shows which is typical for any winter month.  Boundary temps will struggle without elevation compounded by the calendar.  So psu will be posting heavy snow obs before sunrise where I might be posting heavy rain with mangled flakes and the EZF crew will be posting still waiting obs.  

[Bob Chill]

Seriously dudes...this is actually much improved from an already good sounding from the 12z. We're at 66 hours. We all know the risks but how can you not like this? This is a straight up stick on the streets of DC sounding. Right or wrong it's a legit major April event as depicted...

[yoda]

18z GEFS snowfall mean was 4 inches at DCA FWIW 

[Bob Chill]

I want the GFS to be right because it's basically below freezing all day during daylight on Sat for much of the region. Highly dependent on precip falling between 18-0z but it would kick ass to have a sub freezing daytime high. The magnitude on paper will be screwed because it's 42 at 2am but we can use this as material for dummies to STFU for many years to come when the blanket "April blah blah blah" posts happen in the future. Anomalous things happen. Even if only once every 100 years, it proves that blanket statements are weak and dumb sometimes. 

[SnowGolfBro]

3 minutes ago, Bob Chill said:

I want the GFS to be right because it's basically below freezing all day during daylight on Sat for much of the region. Highly dependent on falling between 18-0z but it would kick ass to have a sub freezing daytime high. The magnitude on paper will be screwed because it's 42 at 2am but we can use this as material for dummies to STFU for many years to come when the blanket "April blah blah blah" posts happen in the future. Anomalous things happen. Even if only once every 100 years it proves that blanket statements are weak and dumb sometimes. 

Totally agree. Weather records don’t go back very far relatively speaking. I’m sure there’s been a foot of snow at some point in history in our region. Doesn’t mean that will happen this time but it’s not impossible.

[87storms]

It’s the type of setup where you’d think that at minimum we’d end as a period of snow. Its a significant amount of moisture being depicted with this system with cold air charging in. Gonna be a timing thing I guess.

[snowmagnet]

26 minutes ago, Bob Chill said:

IIRC- the gfs has more of a progressive bias than a warm bias. In this case I can see how that type of bias makes it look like a cold bias because it brings in the air colder with this specific system. However, the GFS definitely leans warmer at the surface quite often and when other guidance disagrees  the gfs is usually wrong. Not sure that applies in this case and the temps on the gfs are actually really good. Soundings are like as good or better than 12z. 

I will say the GFS is the steadiest with the progression/track of the low. The fact that 18z pretty much held identical is fairly important. Yea, it moved "southeast" a little but it was a noise type of bump and not meaningful other than still supporting a pretty nice event. Until the GFS burps NW like the euro/nam I think we are still very much in the game. What happens when 0z gfs looks identical again the the euro moves somewhere between it's last 2 runs? 

I personally ignore the nam almost all the time now. I said this last night...gfs/euro blend is the most accurate short/med range guidance the vast majority of the time. I'm kinda expecting the euro to move back a little more in our favor. It's still razor thin and there's still enough lead time for this threat to vaporize for all but the NW tier but I'm actually leaning towards something more than conversational snow for much of the area. Especially 95 and W. SoMD is really tricky. I'll leave that to the proprietary Prince Frederick Model.

 

ETA: ICON moved in the right direction too. Very interesting. The only bleeding was on the euro but the ens painted a better picture. It kinda has that feel that jumping on the 12z euro as a nail in a coffin is going to end up pre-mature. We'll know if I'm right while I'm asleep later.  

I love your words of wisdom.  Whether they verify or not, you live up to your name.   Thanks!

[donsutherland1]

With both the ECMWF and GFS indicating that Baltimore and Washington, DC could receive 1" or more snow on Friday night and Saturday, a look at the historic data is useful for putting the event into perspective. Climatologically-speaking, it would be a rare event.

Biggest Snowstorms after April 5:

Baltimore:
1. 5.0", April 10-11, 1894 and April 8-9, 1916
3. 0.7", April 9, 1985
4. 0.4", April 13, 1957 and April 12, 1959
6. 0.3", April 7-8, 1972
7. 0.2", April 9, 2000 and April 7, 2007
9. 0.1", April 28, 1898 and April 6, 1990

A total of 10 storms brought measurable snowfall to Baltimore after April 5.

Washington, DC:
1. 4.0", April 6, 1889
2. 3.0", April 11-12, 1918
3. 2.0", April 11, 1894
4. 1.8", April 8-9, 1916
5. 1.5", April 9, 1917
6. 0.8", April 6-7, 1907
7. 0.6", April 9, 1907 and April 7, 1972
9. 0.5", April 28, 1898, April 14-15, 1923, and April 12-13, 1940

Highest Total Snowfall in April:

Baltimore:
1. 9.4", 1924
2. 8.0", 1884
3. 5.0", 1894 and 1916
5. 4.5", 1915
6. 3.0", 1917
7. 2.0", 1885
8. 1.7", 1944
9. 1.3", 1927
10. 1.1", 1887

Washington, DC:
1. 5.5", 1924
2. 4.0", 1889
3. 3.5", 1915
4. 3.0", 1918
5. 2.0", 1894
6. 1.8", 1916
7. 1.5", 1917
8. 1.4", 1907
9. 1.0", 1887 and 1898

All of the snowiest Aprils on record occurred prior to 1950 in both cities. If the ECMWF and GFS are correct, 2018 could wind up on the list for most April snowfall for both cities.

April records go back to 1884 in Baltimore and 1888 in Washington, DC

[mattie g]

3 hours ago, Fozz said:

Those GFS temps are incredible for Saturday morning. Imagine it's April 7 and you wake up to SN+ with temps of 26-28 degrees, especially when the previous day was 60.

#denvering

[Amped]

3 minutes ago, donsutherland1 said:

With both the ECMWF and GFS indicating that Baltimore and Washington, DC could receive 1" or more snow on Friday night and Saturday, a look at the historic data is useful for putting the event into perspective. Climatologically-speaking, it would be a rare event.

Biggest Snowstorms after April 5:

Baltimore:
1. 5.0", April 10-11, 1894
2. 0.7", April 9, 1985
3. 0.4", April 13, 1957 and April 12, 1959
5. 0.3", April 7-8, 1972
6. 0.2", April 9, 2000 and April 7, 2007
8. 0.1", April 28, 1898 and April 6, 1990

A total of 9 storms brought measurable snowfall to Baltimore after April 5.

Washington, DC:
1. 4.0", April 6, 1889
2. 3.0", April 11-12, 1918
3. 2.0", April 11, 1894
4. 1.8", April 8-9, 1916
5. 1.5", April 9, 1917
6. 0.8", April 6-7, 1907
7. 0.6", April 9, 1907 and April 7, 1972
9. 0.5", April 28, 1898, April 14-15, 1923, and April 12-13, 1940

Highest Total Snowfall in April:

Baltimore:
1. 9.4", 1924
2. 8.0", 1884
3. 5.0", 1894 and 1916
5. 4.5", 1915
6. 3.0", 1917
7. 2.0", 1885
8. 1.7", 1944
9. 1.3", 1927
10. 1.1", 1887

Washington, DC:
1. 5.5", 1924
2. 4.0", 1889
3. 3.5", 1915
4. 3.0", 1918
5. 2.0", 1894
6. 1.8", 1916
7. 1.5", 1917
8. 1.4", 1907
9. 1.0", 1887 and 1898

All of the snowiest Aprils on record occurred prior to 1950 in both cities. If the ECMWF and GFS are correct, 2018 could wind up on the list for most April snowfall for both cities.

April records go back to 1884 in Baltimore and 1888 in Washington, DC

All of the predate Regan Airport/Washington National Airport accept 1972.  So the DCA record is only .6"

[BristowWx]

Looking at that historical data venture a guess no one was alive for the DC top 6 April events.  The awesome factor is amped up if we can achieve a spot on that list. We might see history made.  Wow. 

[H2O]

We’ve had the north trend, the dry trend and the happy hour trend.  What’s left?  The cancel trend?

[T. August]

5 minutes ago, H2O said:

We’ve had the north trend, the dry trend and the happy hour trend.  What’s left?  The cancel trend?

Congrats Richmond

[psuhoffman]

5 minutes ago, H2O said:

We’ve had the north trend, the dry trend and the happy hour trend.  What’s left?  The cancel trend?

It's happening trend 

[grhqofb5]

1 hour ago, Eskimo Joe said:

The GFS has a known bias of transitioning too quickly from rain to snow.  The Euro should be given a greater weight in these situations.

Isn't the elimination of know biases the whole point of models?  If the bias is known, the model should correct for it.  If it doesn't then it's not providing the most accurate projection.

[nw baltimore wx]

I'm not going to quote it, but that post by @donsutherland1 above is one of many reasons why this forum is so awesome.

And don't worry @stormtracker, I'm writing the check now.

[cae]

Extended RGEM has been going back and forth the last few runs, but it doesn't look like a north trend to me.  The 18z GGEM also looked much better than the 12z GGEM.

[donsutherland1]

Also, below is the list of biggest April snowstorms for Baltimore and Washington, DC:

Baltimore:
1. 9.4", April 1, 1924
2. 5.0", April 10-11, 1894 and April 8-9, 1916
4. 4.5", April 3, 1915
5. 0.7", April 9, 1985
6. 0.4", April 13, 1957, April 12, 1959, and April 1, 1964
9. 0.3", April 7-8, 1972
10. 0.2", April 9, 2000 and April 7, 2007

Washington, DC:
1. 5.5", April 1, 1924
2. 4.0", April 6, 1889
3. 3.5", April 3, 1915
4. 3.0", April 11-12, 1918
5. 2.0", April 11, 1894
6. 1.8", April 8-9, 1916
7. 1.5", April 9, 1917
8. 1.0", April 1-2, 1887
9. 0.8", April 6-7, 1907
10. 0.6", April 9, 1907 and April 7, 1972

[WestminsterSnowCapitalMA]

Nam about to deliver, coming in, COLD!

[BaltimoreWxGuy]

Yeah I think to a degree we’re gonna get NAM’d