This page has daily 12Z model output discussion as it comes in. Discussion updated Monday-Friday by 1:15p.
HEADLINE: MID-DAY GFS TRENDS SNOWIER, SETS UP ACTIVE WEEK 2 IN U.S….
North America: The 12z GFS has some significant differences in its handling of a snow threat starting in the Plains on Sunday, which has major downstream ramifications. This initial disturbance is more vigorous, upping snow potential from Kansas across the central belt into the western Lakes. The big difference is the transfer to a coastal secondary low on Monday, greatly enhanced here relative to 00/06z runs. This stronger low pulls in a more powerful Great Lakes trough at the start of week 2, which sets up a more favorable pattern for Midwest/Eastern U.S. snow and ice in the middle of week 2, which just is starting to show up on day 10 in the Plains on this run. Look for more of a trend in this direction over the next few days.