During La Niña, models tend to over amplify weather systems several days out from onset. Overamped, too much moisture, only to see it correct toward the onset time. This latest event is a prime example as across the board guidance was giving a 6-10” area wide event and more like 10”+ on the euro, only to cave to a minor system...even by I-70 standards. Last storm very similar with the euro giving 25-30” at day 4/5 only to be cut back. For the hobbyist, it might be a sting to the gut, but for those working in the field, the inconsistency and wild swings have made forecast ops and communication to high level partners even up into high tier Gov partners a nightmare! Briefings for these “major” events that crop up at day 3-5 in NWP gain attention quickly then to have the rug pulled after you’ve messaged people is tough. One factor, could be minor, but it is a factor in such inconsistent data is the lack of domestic air travel in the U.S. we know the euro model in particular relies on aircraft data which air travel is 1/10th of what it was. Same with other guidance. Perhaps other factors we don’t know about. Niña years are tough as it is. Two conclusions I can draw from this season is... 1) the euro is not what the euro was, and 2) the NAM is useful outside its perceived “wheelhouse”. NAM is great at depicting changes, details in the pattern evolution that is not seen in the globals. It’s done well this season in that regard, overdone with front end waa snow. 3) it’s guidance only! Not verbatim. Know your patterns and climo vs model chasing.
I expect the same trends with all the weather systems depicted through the 2/20 time frame.