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Wintry Winter Storm Dec 7-10

Deform band developing.... silly NAM
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Don't know how this relates to winter weather but I've seen many times where the NAM over amps lows when it comes to severe weather.
 
RollTide18 said:
Don't know how this relates to winter weather but I've seen many times where the NAM over amps lows when it comes to severe weather.
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As I mentioned earlier this oversimplification of lows is related to the BMJ convective parameterization (CP) in the 12 and 32km versions of the NAM. Extratropical convection is outside the parameter space of this CP which was intended for use in the deep tropics, thus it can't handle cold pools, and isn't as good w/ detrainment.... Here however the NAM's amplification of this low is not exclusively related to its piss poor CP scheme, but wholesale changes in the speed of disturbances within the first 36-48 hours of the run over the southwestern US contributed a lot to its stronger solution here as well. This is inherently easier to predict for a NWP model than diabatic heating induced from convection
 
whatalife said:
LOL! Stupid NAM!
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Yeah for my area that deform band is doing work but here is the more realistic map, huge difference, here anyway but I'm not complaining
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Even though the NAM isn't accurate past 36 hours, you begin to wonder if it is accurate in some cases beyond 36 hrs. Especially if the NAM keeps showing of what it has been showing for the most part over and over, the same similar setup on each run. I wouldn't count out that the NAM is totally inaccurate with this particular system.
 
Brick Tamland said:
The amounts might be too much, but the Euro and the NAM are showing that classic RDU jackpot zone.
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Well at least for now they are. The EPS shifted NW appreciably overnight w/ heaviest snows centered towards the climatologically more favored NW piedmont and if the NAM continues to move towards a solution w/ a stronger coastal low esp once we actually get inside 48 hours from verification that could spell trouble and game over for RDU.
 
Webberweather53 said:
Well at least for now they are. The EPS shifted NW appreciably overnight w/ heaviest snows centered towards the climatologically more favored NW piedmont and if the NAM continues to move towards a solution w/ a stronger coastal low esp once we actually get inside 48 hours from verification that could spell trouble and game over for RDU.
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What will be will be. I don't think we get totally blanked. Just seeing snow fall at this stage of winter would be great.
 
whatalife said:
Yeah they do. They are never what they seem.


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The ratios alone will automatically knock down those totals on the clown maps 30% plus or minus 10%, the model here assumes they're all 10:1 which is certainly not going to be the case here... When you then include melting from mixing w/ rain, radiation from the ground, and even once the snow has accumulated, if the air temperature is above freezing, some melting will occur, you lose at least a third to as much as half of the snow
 
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