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Precipitation forecasts in GFSX

GW
Glenn White, modified 8 Years ago.

Precipitation forecasts in GFSX

Youngling Posts: 3 Join Date: 1/12/15 Recent Posts
Email fromAndy E:
 
I have been watching the new GFS on the WR side by side web page -- initially the two models looked pretty much the same -- but now that the synoptic regime has become more active during the last week -- there are some notable differences - especially during the last 3-5 days
 
As a reminder
  • I like to click on the Dprog/dt button -- upper left corner
  • Then step through the animation by hand  --
 
Note:  as always -- please double check the times -- the data acquisition scripts to pull data from NCEP are not infallible
 
Question for NCEP:  This is subjective feedback -- but some of the forecast solution bouncing around and differences between the two models is pretty significant.  
  • Please look at the surface and precip forecast fields, the new GFS model  precipitation amounts can vary a lot run to run and be much different at times from the current GFS.   The new GFS solutions  seems to bounce around more than the op GFS version.   I believe more than you can write off as natural model variability.  
Some of the WR STID folks have noticed similar differences this week.   
 
I am suspicious that the  data assimilation first guess fields are  more different (run to run) between the two models than we expected. 
 
 NCEP -- you have some better diagnostic tools...what is your interpretation?   Is there an issue with moisture data assimilation?
 
Hopefully this gets a conversation started 
GW
Glenn White, modified 8 Years ago.

RE: Precipitation forecasts in GFSX

Youngling Posts: 3 Join Date: 1/12/15 Recent Posts

Equitable threat scoeres for the GFSX seem higher than the operational, but so is the standard deviation of 120 hr forecasts of precip every 6 hours.  Th latter is consistent with less continuity.

EMC will try to look at this.

 

Glenn White

 

GW
Glenn White, modified 8 Years ago.

RE: Precipitation forecasts in GFSX

Youngling Posts: 3 Join Date: 1/12/15 Recent Posts
Based on 13 months of retrospective so far, for thresholds of 0.2 to 15 mm and forecast lengths of 0-24 to 84-108 hrs, seventy of 120 categories  of precipitation forecasts show statistically significant improvement in the GFSX compared t the GFS.