"In response to concerns raised during the GFSv17 NWS Field Evaluation regarding high dewpoint biases over the Western United States (WUS) in April/May, we request permission to modify the existing 2-m specific humidity (q2m) diagnostic.
In summary, the goal is to mitigate high dewpoints in the WUS without negatively impacting the positive results seen over other regions and time periods. We accomplish this by blending the existing q2m and first model levels, using weights determined by vegetation cover. The change is applied in UPP so that the newly implemented soil DA will not be impacted." - Mike Barlage
"In response to concerns raised during the GFSv17 NWS Field Evaluation regarding high dewpoint biases over the Western United States (WUS) in April/May, we request permission to modify the existing 2-m specific humidity (q2m) diagnostic.
In summary, the goal is to mitigate high dewpoints in the WUS without negatively impacting the positive results seen over other regions and time periods. We accomplish this by blending the existing q2m and first model levels, using weights determined by vegetation cover. The change is applied in UPP so that the newly implemented soil DA will not be impacted." - Mike Barlage