Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 417 AM EDT Fri Jul 10 2020 Valid Jul 10/0000 UTC thru Jul 13/1200 UTC ...See NOUS42 KWNO (ADMSDM) for the status of the upper air ingest... 00Z Model Evaluation with Final Preferences/Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Mid-level shortwave crossing the Great Lakes/Ohio Valley through Sat... ...Associated cold front crossing the Great Lakes... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: non 00Z GFS blend Confidence: Below average 07Z update...There is better agreement with the mid-level shortwave from the 00Z ECMWF/UKMET/CMC, which show the 00Z GFS out on its own with a faster track as the vort center tracks into the northeast. Run to run consistency has been poor with this system and the changes seen in the 12Z/10 ensemble spaghetti plots compared to the previous 00Z/10 cycle are dramatic valid Saturday morning. The latest consensus is near the agreeable GEFS/EC ensemble means which show the mid-level trough progressing slower than the 00Z GFS. A blend of the 00Z NAM (weaker/north) and 12Z ECMWF (stronger/south) may be the best compromise as no single model solution looks ideal here. The 12Z CMC is weaker and faster than the ensemble means with the mid-level trough while the 12Z UKMET is rather strong and north with the mid-level low center. ...Tropical Storm Fay... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend through 12Z/11 closest to 03Z NHC advisory 00Z ECMWF/UKMET blend 12Z/11-12Z/12 closest to 03Z NHC advisory Confidence: refer to NHC 07Z update...The 00Z ECMWF/UKMET adjusted faster, closer to the 03Z NHC advisory, leaving the 00Z deterministic consensus fairly close to the 03Z NHC advisory for the track of Fay. Beyond Saturday morning, the models diverge leaving the 00Z ECMWF/UKMET closest to NHC. The deterministic models vary with closeness to the 03Z NHC advisory for Fay over the next 48 hours. However, overall, a blend of the 00Z NAM/12Z ECMWF and 12Z CMC is nearest to the track for Fay as the storm moves into the Northeast Friday night. The NAM/ECMWF combination falls a bit west of the NHC track, and a possible over amplification of an upstream (OH Valley) trough seen in the 12Z ECMWF may be to blame as discussed in the above section. ...Mid-level shortwave to cross the northern Rocky Mountains early Friday morning, move atop the ridge and into the Upper Midwest by Sat evening, reaching the OH Valley on Sun... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Average 07Z update...Adjustments in the 00Z ECMWF toward the remaining consensus support better agreement with this feature as it crosses the Mississippi River Valley. Despite some minor timing differences, the agreement is good enough at this point to support a general model blend. The 00Z NAM/GFS are close to one another with this system as it nears the Mississippi River, but tend to be a little slower than the ensemble means. Meanwhile the 12Z UKMET/CMC are south of the ensemble means. A blend of these models may be best for this system with only the weakly defined 12Z ECMWF standing out significantly from the remaining consensus. ...Longwave trough axis moving into western Canada and the northwestern U.S. on Sun... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Average 07Z update...Only minor timing adjustments were noted in the 00Z ECMWF/UKMET/CMC compared to their previous 12Z cycles. Given the minor differences noted with the large trough axis reaching the northwestern U.S. this weekend, a general model blend will work well here for the preference. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml This product will terminate August 15, 2020: https://www.weather.gov/media/notification/pdf2/scn20-58pmdhmd_term ination.pdf Otto