Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
241 AM EDT Thu Jul 12 2018

Valid Jul 12/0000 UTC thru Jul 15/1200 UTC

...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...

12Z Model Evaluation...with Final Preferences and Confidence
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

...Overall Model Analysis for the CONUS...

Overall Preference: General model blend; less weight on 00Z GFS
General Confidence: Average

---06Z UPDATE---
No changes to the preliminary preference or reasoning.

---PREVIOUS DISCUSSION---
For the next few days, most of the stronger flow aloft will be
restricted north of the US-Canada border, and thus the 500mb
heights across the CONUS generally vary by less than 50 meters at
most locations. Thus, the pattern overall lacks any significant
synoptic forcing and convective processes may be able to drive the
placement of boundaries (and future rainfall) from day to day.
Most deterministic models are in good agreement in their mass
fields. For this reason, a general model blend is preferred
overall. The confidence level is rated as average despite the mass
field agreement, as convective processes will play a greater role
in the distribution of QPF, and this lowers confidence in the
forecast.

Less weight was placed on the GFS for the WPC QPF, particularly
related to the forecast in the Midwest region. The GFS does not
seem to advance the front as quickly to the south as other models,
and has a less consistent QPF than other models. The preference
was to incorporate less of the GFS, with a greater reliance on the
NAM and ECMWF, particularly in this region.

One final note: Hurricane Chris is now well off the U.S. East
Coast, with no rainfall expected in the CONUS. For details on the
forecast for that tropical cyclone, including model preferences,
refer to the official NHC forecast products.


Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml

Lamers