Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1217 AM EDT Tue Jun 30 2020 Valid Jun 30/0000 UTC thru Jul 03/1200 UTC ...See NOUS42 KWNO (ADMSDM) for the status of the upper air ingest... 00Z Model Evaluation Including Preferences and Forecast Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Closed low anchored over New England ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Non-CMC blend Confidence: Above average The latest model guidance maintains the upper low over the interior of New England going through early Thursday. Thereafter, the energy is forecast to shift off the east-southeast and offshore of the East Coast. The guidance is rather well clustered with this evolution through the period, but the 12Z CMC does end up being slower to advance the height falls offshore by early Friday. A non-CMC blend will be preferred with this system for the time being. Deep upper trough/closed low across the Intermountain West ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Blend of the 00Z GFS/12Z UKMET/12Z ECMWF Confidence: Average The strong upper-level low over the Intermountain West will lift northeast over the northern Rockies through Tuesday before merging with another shortwave trough and associated close low approaching southwest Canada. The consolidation of this energy will result in a large closed low over the Pacific Northwest to northern Rockies going through Wednesday. By Thursday, yet another compact shortwave and associated closed low will drop south down the coast of British Columbia and into the Pacific Northwest which will help to drive the larger closed low up into southwest Canada. The 12Z CMC is overall again the most out of phase compared to the remaining guidance as it suggests a stronger closed low ejecting north out of the northern Rockies and into southwest Canada. It also is the most progressive with the energy dropping down the coast of British Columbia and the Pacific Northwest. The 00Z NAM for its part is also modestly deeper than the model consensus with the broader large scale closed low evolution. The better model clustering resides again with the 00Z GFS, 12Z UKMET and 12Z ECMWF, so a blend of these solutions will be preferred. MCV/Weak mid-level low over northern MN ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Above average The MCV and associated weak mid-level closed low over northern MN this evening will lift north through western Ontario over the next 24 hours. Model spread is minimal with this evolution and so a general model blend will again be preferred with this feature. MCV crossing the middle and upper MS Valley Tuesday/Wednesday ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Blend of the 12Z CMC/UKMET/ECMWF Confidence: Slightly below average A convectively enhanced MCV is forecast to track through the middle and upper MS Valley region going through Wednesday. All of the global models agree on this scenario with the 12Z non-NCEP models well clustered on their timing of the energy as it crosses the upper Midwest and eventually arrives across southern Canada. The 00Z GFS is a tad slower than the non-NCEP guidance. The 00Z NAM though stalls the energy out over western IL on Tuesday and then drops the energy southeastward through the Mid South by Thursday. With somewhat limited confidence, the preference will be toward a blend of the more progressive and northerly tracking non-NCEP suite of guidance which is favored by the bulk of the latest ensemble guidance. Mid-level closed low over the Gulf Coast by Friday ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Non-NAM blend Confidence: Above average A mid-level trough and developing closed low is expected to form over the Gulf Coast states by Friday as weak shortwave energy drops down through the Mid South. The 00Z NAM is a bit stronger than the global models as it takes the aforementioned MCV over western IL down to the southeast which results in a more amplified trough over the Gulf Coast region. A non-NAM blend will be preferred for the time being since the global models are generally well clustered. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Orrison