Wednesday, April 4, 2018

Come on.....its gotta end!

4/5  Big shift south overnight on NAM and NAVGEM - caving to GFS and Euro?  So what happened?  Last three runs of nam at surface, 500mb and the precip.



12z nam 24 hr precip trend
as is snow



4/4 update

18z GFS ensemble showing north trend with precip.


4/4

Several possibilities coming ahead.

First, Friday morning should see some snow.  Should be light and turn to rain.  850 temps support snow the entire event, all models, but surface temps do not.  Should be very light:
Euro qpf from 12z run

FRI 06Z 06-APR  -2.6    -9.1    1021      67      15    0.00     537     520    
FRI 12Z 06-APR   0.2    -7.7    1020      61     100    0.00     539     523    
FRI 18Z 06-APR   3.3    -1.4    1012      84      83    0.07     543     533 
 
  
GFS qpf 12z run
FRI 12Z 06-APR   1.9    -7.7    1018      52      98    0.00     537     523    
FRI 18Z 06-APR   7.4    -3.1    1010      71      69    0.09     541     533 
 
NAM qpf 18z run
FRI  8A 06-APR   0.3    -7.3    1018      64      88    0.00     537     523    
FRI  2P 06-APR   8.4    -2.0    1006      71      54    0.17     539     533    
FRI  8P 06-APR   9.6    -0.3    1007      50      82    0.00     545     539     

Then, we deal with Saturday.
 
NAVGEM rule is in effect - when the NAVGEM is the slowest and furthest NW model, then something is wrong.
Euro
 
 GFS

And confusing things more is the NAM which is the earliest and furthest north.  I've come to respect 
the NAM lately even when it does wacky things
 


So it just dumps over 6" per below for DXR -
  

NAM printout
SAT  8A 07-APR  -1.2    -3.5    1008      92      97    0.16     547     540    
SAT  2P 07-APR  -1.1    -8.2    1007      89      98    0.58     542     537    
SAT  8P 07-APR   0.4    -8.5    1008      64      27    0.02     539     533 
 
And over a foot in other places
GFS and Euro focus further south...which in previous storms this year end up going north.

 
 Which brings us back to the NAVGEM rule - its likely these snow areas shift north. 
At least its the weekend and during the day.

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