Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 312 AM EST Thu Jan 03 2019 Valid Jan 03/0000 UTC thru Jan 06/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 00Z Model Evaluation...with Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ***Overall pattern across the CONUS*** ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend through 05.00z, then ECMWF/UKMET/NAM/GEFS mean blend Confidence: Slightly above average 08z update: With the remainder of the 00z guidance in, there is now better agreement with the surface features and mid/upper level pattern for the southern stream closed low that will move across the central/eastern US. A general model blend would suffice for these areas. Across the Western US, there continues to be some differences in the models, but it has remained consistent from the previous cycle. The CMC continues to be slow with the surface low pushing into California on Saturday while the GFS is on the faster side of the consensus. The previous WPC preference will remain the same with the rest of the guidance now in. ---previous discussion--- Distinct northern and southern stream energy will be progressive across the CONUS through the forecast period. The main forecast systems to affect the CONUS will be a closed low in the southern stream currently moving across Texas with its associated surface low. The system will track across the Southeast US then lift through the Mid-Atlantic. Through 48 hours (05.00z) there is good model agreement between the 12z guidance and the early 00z guidance (GFS/NAM). Beyond that time period, there are spatial and temporal differences with the surface low track. The GFS and NAM are faster with the low and also further east as it races off the coast of Cape Cod while the ECMWF/CMC/UKMET are a bit slower and also further up the coast before exiting east. Preference would be the slightly slower solutions but will also include the latest GEFS mean as a compromise to the GFS. Across the western US, an atmospheric river will push into the far Pacific Northwest Friday Morning and will bring locally heavy precipitation to the favored upslope regions. In the mid/upper levels, there are not too many differences with the shortwave pushing into the coastline. At the surface, the CMC/ECMWF solutions are faster taking the surface low onshore compared to the UKMET/GFS/NAM. Another storm system will then approach the California coast by Saturday, characterized by a broad longwave trough. The GFS is faster compared to a consensus, while the CMC is considerably slow and is likely an outlier that should be discarded. The UKMET/NAM/ECMWF are reasonably clustered and within the ensemble spreads. So for this cycle the WPC preference is for a general model blend through 48 hours (05.00z) then more weight toward the 12z ECMWF, 12z UKMET, 00z NAM with some inclusion of the 18z GEFS mean. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Taylor