Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 228 PM EDT Sat Jun 01 2019 Valid Jun 01/1200 UTC thru Jun 05/0000 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 12Z Model Evaluation Including Preferences and Forecast Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Overall Pattern Across the CONUS... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General Model Blend Exception: Weighting toward EC in Northeast Weighting toward GFS/NAM in Southern Plains Confidence: Slightly above average 19z update: The 12z Non-NCEP guidance continue to be weaker with the ridging across TX allowing for increased eastward progression of the upslope flow regime relative to the GFS/NAM, with the UKMET most aggressively bringing moisture out of the tropical wave into S TX, though with the ECMWF trending a bit south with the wave, it did not progress convective clusters as far east as the 00z run. So will continue to favor a general model blend but weighting toward the westward GFS/NAM. In the northeast, consistency continues with the UKMET/ECMWF/CMC all north of the stronger, southern shortwave in the NAM/GFS. Still a general model blend can be employed with confidence given low level mass fields/QPF are in agreement but still would weight higher to the ECMWF/ECENS members relative to the other guidance. ---Prior Discussion--- The greatest model spread over the next few days remains with the Great Lakes/Northeast amplifying trof Sunday into Monday but also the upscale influence of the tropical wave in the Bay of Campeche and interference/enhancement with tidal upslope regime convective complexes across the Southern Plains within the broad southwesterly flow aloft. The zonal flow across the northern third of the CONUS as well as the approach of a broad Gulf of AK closed low nearing the Northwest by 00z Wed seem to have solid model agreement (with exception of a flatter CMC solution). In the northeast, the NAM has joined the stronger/more compact solution of the GFS that remains continuity with its prior runs. As such, both dig the trof harder and further south into the CONUS directly, though with decreasing differences to the QPF or even much in the surface mass patterns. The NAM nearing the GFS occurs while the CMC is trending away toward the northern, less sharp ECMWF camp that includes the UKMET. The ECMWF has been quite consistent without such a sharp/deep compact system seems more logical in a multi-"Fujiwara" binary interaction of mid-level internal vorticity centers where interactive shearing occurs. It should be noted, the 12z NAM continues to bank the precursory coastal surface wave more cyclonically back west toward the opening of the Bay of Fundy, drawing a bit too much moisture back west, so perhaps a lower weighting for this specific feature; otherwise a general model blend will work for this system favoring the ECMWF/CMC/UKMET a bit more in weighting aloft. In the Southwest, the weaker than normal stalled closed low remains well agreed upon through the bulk of the forecast, though minor difference particularly in absolute depth remain leading to either weaker height packing through the Southern Plains (influencing early morning weakening of MCSs/complexes) and strength of the ridging between it and the approaching tropical wave in the Bay of Campeche. The 00z CMC is most weak and starts even migrating the trof out east into the High Plains by 00z Wed, which does not gel well with the ensembles or overall trend. The ECMWF is second weakest, and as such allows for weaker ridging in the Southern Plains, allowing for convection to driver further east, and subsequently reducing the westward migration/return of LLJ/moisture into the upslope flow regime. The GFS/NAM as such a a bit further west with each daily/tidal convective development Sun to Tues. Given time of year, ridging in S TX and squeeze with approaching tropical wave would suggest ridge amplification so would hedge more GFS/NAM in a non-CMC blend. Confidence is average, contingent on magnitude of tropical cyclone development. Model trends at www.wpc.noaa.gov/html/model2.html 500 mb forecasts at www.wpc.noaa.gov/h5pref/h5pref.shtml Gallina