Jump to content
  • Member Statistics

    17,606
    Total Members
    7,904
    Most Online
    ArlyDude
    Newest Member
    ArlyDude
    Joined

The Second Wave: Dec 10 (Model Discussion)


stormtracker

Recommended Posts

  • Replies 1.3k
  • Created
  • Last Reply

Based on the model data in at 9:00 am (just the NAM's 12Z run had come in), it may have been when you blend the GFS/Euro/NAM up through that point. But of course it's understandable that LWX would want to get a watch out now that we are within 24 hours of the next event. 

 

My comment was more questioning CWG's approach to describing the issuance of the watch... but I see that the post has been revised/modified already. 

 

Ah, fair enough.

 

What I would really like to avoid is schools bringing the kids in mistakenly and then sending them back again around 10:00 during heavy snow, if that's how this snow chance develops. If the Watch helps alert schools to be ready to call off, I am fine with it. I would prefer not to have to go retrieve my kid during a heavy snow event, at any rate.

Link to comment
Share on other sites

Classic SE to NW orientated vertical circulation. Lowest-level VVs SE of the area (850mb e.g.) to mid-level VVs over the area (700mb over DC and 600-500mb to the NW). This thing is a ripping, tilted frontal structure.  

Link to comment
Share on other sites

Ah, fair enough.

 

What I would really like to avoid is schools bringing the kids in mistakenly and then sending them back again around 10:00 during heavy snow, if that's how this snow chance develops. If the Watch helps alert schools to be ready to call off, I am fine with it. I would prefer not to have to go retrieve my kid during a heavy snow event, at any rate.

Yeah, that's a huge concern.  At that point, safer to keep them till 3pm when at least it isn't still snowing. Unfortunately, they rarely do that but instead risk having parents and buses come pick them up. If schools are smart, they'll just make tomorrow the 4th weekend day, especially with all the ice that will have refroze tonight and will be covered by the fresh snow.

Link to comment
Share on other sites

Doesn't look like the snow would go anywhere either.........

 

 

TUE      06Z        10-DEC      -0.8      4.8      0.00
TUE      12Z        10-DEC      -0.8     -2.3      0.15
TUE      18Z        10-DEC      -1.0     -4.8      0.49 
WED     00Z        11-DEC      -2.9     -8.9      0.00 
WED     06Z        11-DEC      -8.0     -6.4      0.00
WED     12Z        11-DEC      -10.3   -4.9      0.00
WED     18Z        11-DEC      -2.5     -4.7      0.00 
THU      00Z        12-DEC      -12.8    -5.6     0.00 
THU      06Z        12-DEC      -5.8      -9.8     0.00 
THU      12Z        12-DEC      -7.4     -11.9    0.00 

Link to comment
Share on other sites

I hope people don't overreact when the Euro shows a nice wide swath of 0.25 - 0.4"....It is what the euro does...it is steady...it usually doesn't swing wildly...it tempers our expectations....when it honks it really honks...i.e...NE Blizzard last winter...But it is a risk to ignore it...It helps set up the range of possibilities...

Link to comment
Share on other sites

Thunder?

 

I'm not sure. The h7 theta-e advection with the initial shot may be enough to prevent that but the soundings do get more unstable with time, especially north of the DC-area. Like around 15-18z the soundings grow less stable, but everything is disjointed then. Will the broad cool air advection after the morning surge be enough to ruin convective chances? We get a real strong shot of differential vorticity after the morning shot, but there will be opposing forces here. We'll see...

Link to comment
Share on other sites

I'm not sure. The h7 theta-e advection with the initial shot may be enough to prevent that but the soundings do get more unstable with time, especially north of the DC-area. Like around 15-18z the soundings grow less stable, but everything is disjointed then. Will the broad cool air advection after the morning surge be enough to ruin convective chances? We get a real strong shot of differential vorticity after the morning shot, but there will be opposing forces here. We'll see...

Very nice explanation HM. Regardless of the thunder, what you're saying is there will be some very very heavy snow in some places? It looks pretty likely rates in a few locales could be phenomenal. 

Link to comment
Share on other sites

I think the watch is fine. Sometimes we assume we know more than we do with this stuff... see yesterday snow. If I had to bet I'd take the under on 5" in DC but it's possible. 

 

I think it's fine as well.   CWG did go a little overboard on it though.  I would have just said...While 5" is possible, it's not probable or something like that.   But that was before I saw the GFS.    NWS doesn't look so aggressive now.

Link to comment
Share on other sites

I think it's fine as well.   CWG did go a little overboard on it though.  I would have just said...While 5" is possible, it's not probable or something like that.   But that was before I saw the GFS.    NWS doesn't look so aggressive now.

"We think this watch may be a bit aggressive and that 5 or more inches of snow is a low probability (not out of the question)." From the article.

Link to comment
Share on other sites

I don't know.  This looks like you'd have to look harder to find reasons the watch wouldn't verify (not enough QPF, initial warm nose could cut ratios/IP) rather than why it would (plenty of cold, upper level support, banding).  While it might not verify directly at DCA, or over the entirety of the watch area, it looks like a high probability that it would verify in many areas and that would make the watch warranted.

Link to comment
Share on other sites

I don't know.  This looks like you'd have to look harder to find reasons the watch wouldn't verify (not enough QPF, initial warm nose could cut ratios/IP) rather than why it would (plenty of cold, upper level support, banding).  While it might not verify directly at DCA, or over the entirety of the watch area, it looks like a high probability that it would verify in many areas and that would make the watch warranted.

good reasoning, nice post.

Link to comment
Share on other sites

I think it's fine as well.   CWG did go a little overboard on it though.  I would have just said...While 5" is possible, it's not probable or something like that.   But that was before I saw the GFS.    NWS doesn't look so aggressive now.

One of the things about the internet is people tend to use "we" instead of "I". But who knows. I totally flubbed the max snow area yesterday.. in fact I argued against far N&W the day prior. 

Link to comment
Share on other sites

Very nice explanation HM. Regardless of the thunder, what you're saying is there will be some very very heavy snow in some places? It looks pretty likely rates in a few locales could be phenomenal. 

 

The biggest factor against tomorrow is time/alignment, really. With a more north-south alignment over the area, no band may sit over a spot too long (but they may not have to anyway). The setup tomorrow may prevent large-scale subsidence from ruining snow shield over the area but there still could be a decent band across PA. Up here, the alignment is more tilted with better dendrite making. If this becomes strong enough, it will take its toll on the banding to its south. For now, modeling says no and the vertical structure, circulation seems pretty classic, even if brief.   

Link to comment
Share on other sites

I don't know.  This looks like you'd have to look harder to find reasons the watch wouldn't verify (not enough QPF, initial warm nose could cut ratios/IP) rather than why it would (plenty of cold, upper level support, banding).  While it might not verify directly at DCA, or over the entirety of the watch area, it looks like a high probability that it would verify in many areas and that would make the watch warranted.

that's all well and good but in snow forecasts it's like 80% we live in a bad snow area and 20% the rest. ;)

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.

×
×
  • Create New...