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Feb 13: The little storm that could (for some)


Ian

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Yeah...I'm not sure.  The fundamental physics are the same.  Maybe someone can jump in with specific (and more accurate) details.  The initial conditions (in the form of RAOBs, surface obs, etc...) are generally at a coarser resolution than the model gridding.  Doubly so with the hi-res NAM.  So, those values are interpolated to a finer mesh and then the model is run forward.  IMO, the hi-res is good for terrain-related questions (CAD, LEF, etc...) but doesn't really buy us much here.  

Actually, it depends on what people are referring to when they say "Hi-Res NAM".  The NAM is actually run as a complex set of nested models, including the 12km parent nest (the usual NAM, huge, nearly hemispheric domain)....but then there are several one-way nests that are run inside of it (the 4km CONUS nest, which is what I assume people refer to as the Hi-Res NAM, Alaska nest, relocatable 1.5 km fire wx nest etc.).  The initial conditions are not that much coarser than the 12 km resolution, IIRC, but they do use an "unfilled grid", so it may be something like half of the spatial resolution as the model....but you're right about the 4km nest (it's essentially just interpolated/scaled down to that grid).

 

However, there are also the Hi-Res window runs (NMM and ARW), which are separate from the nested NAM runs......and I think these are just initialized from the NAM ics (interpolated down).

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Congrats to Bob Chill...GFS led the way on this one, even though the outcome will probably be underwhelming..It is the 2nd best model since we don't have good graphics for the UKmet, it holds its own with the euro...it impressed me this storm..euro was a fumbling mess for a while

 

Appreciate it but it's bittersweet. I just wanted to break the damn streak. Not off the table but teetering precariously on the edge.

 

The euro is always a little off when a sw digs through the 4 corners. Sometimes it holds it back when they're strong and sometimes it doesn't pick up on it when they're weak. My reasoning was the gfs/nam handling of the sw early on. They were so steadfast (and believable) that it was hard not to go with it.  

 

But at the end of the day the mission is in jeopardy and has been for days. I've looked at so many panels in the last week that my pupils are 16:9 and I need laser surgery. 

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The problem with snow IMBY is that it's going to start as rain. Temps at the start will be low 40s or upper 30s. Soundings show surface-925mb temps above freezing through about the first half of the precip on the NAM. Then, it finally cools down enough for snow to reach the ground but by then the heaviest rates might be moving away. Combined with the wet ground and the barely 32° surface/2m temps it'll be hard to get more than 1.5" snow unless it cools down faster. I do like the cooler trend on all models, but the NAM is cooler and wetter than both the GFS and Euro. I like a compromise between the NAM and GFS because IMO the Euro hasn't modeled this one that well. In my backyard I am guessing .3" of rain changing to snow and then around an inch of sloppy wet snow overnight. The heaviest precip should be around midnight on Thursday AM and clearing out around rush hour.

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Appreciate it but it's bittersweet. I just wanted to break the damn streak. Not off the table but teetering precariously on the edge.

 

The euro is always a little off when a sw digs through the 4 corners. Sometimes it holds it back when they're strong and sometimes it doesn't pick up on it when they're weak. My reasoning was the gfs/nam handling of the sw early on. They were so steadfast (and believable) that it was hard not to go with it.  

 

But at the end of the day the mission is in jeopardy and has been for days. I've looked at so many panels in the last week that my pupils are 16:9 and I need laser surgery. 

 

Don't quit yet Bob.  This hasn't happened yet, and the NAM did get colder (didn't it?  too lazy to look).  These always seem to trend colder as we get close.  Get some radiational cooling tonight, good thick cloud cover in the morning, precip to limit heating, thump as daylight wanes.......it can happen.

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he usually is very skeptical because of the cold bias...if you split the GFS and NAM then IAD region had a shot at accumulation after say hour 34 or 35

 

I just finished an article so I'll hold off saying much until after Jason gets it up.  I will say I think that a compromise between the two models. 

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Don't quit yet Bob.  This hasn't happened yet, and the NAM did get colder (didn't it?  too lazy to look).  These always seem to trend colder as we get close.  Get some radiational cooling tonight, good thick cloud cover in the morning, precip to limit heating, thump as daylight wanes.......it can happen.

 

Didn't mean to imply that I quit. It's a real a threat as any we've had this year (boy that says alot). 

 

The wildcard is the dynamics. Zwyts said it concisely. The swath of precip running  from ar/ok trough tn-ky-wv says a lot. That's our money maker and it really won't be resolved until we're really close in. I will say that I doubt that it gets any better than the last nam precip wise. Most likely less if I had to guess. We'll micro-analyzing rates and temps until the cows come home. 

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Didn't mean to imply that I quit. It's a real a threat as any we've had this year (boy that says alot). 

 

The wildcard is the dynamics. Zwyts said it concisely. The swath of precip running  from ar/ok trough tn-ky-wv says a lot. That's our money maker and it really won't be resolved until we're really close in. I will say that I doubt that it gets any better than the last nam precip wise. Most likely less if I had to guess. We'll micro-analyzing rates and temps until the cows come home. 

The problem is that the temps are in this case related to the vertical motion and precipitation rates. Decrease them and the temps will be warmer.  That's the rub and why going towards a temp profile compromise probably makes sense.

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