Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 444 AM EDT Sun Mar 20 2022 Valid 12Z Sun Mar 20 2022 - 12Z Wed Mar 23 2022 ...Utah and Rockies onto the southern Plains... Days 1-3... A negatively-tilted trough axis currently digging over southern California will close into a low as it crosses AZ and pushing into NM tonight. This mid-level low is now progged to shift a bit farther east than before, over the TX Panhandle by late Monday before turning up the Plains and interacting with northern stream troughing to result in a sprawling low over the central Plains. The surface low develops over the southern High Plains of eastern NM Monday then before slowly shifting northeast to the Midwest through Wednesday. Ample Gulf moisture wrapping around the low as it pivots up the Plains Monday into Monday night is still likely to produce a band of potentially heavy snow NW of the low center. This looks to be less focused on the Raton Mesa (though heavy snow is sure to still fall given the topographic enhancement) near the CO/NM border from recent days with banding more over the Plains. Dynamic cooling in a rather marginal thermal environment, but under the upper low should result in snow band development over the TX Panhandles late Monday/Monday night. Day 1 snow probabilities over 6" are moderate for the NW WY ranges and for Day 1.5 portions of the CO Rockies. There are still moderately-high probabilities for over 6" for the Raton Mesa to the Sangre de Christos which is down from recent days. As of now the Day 2.5 snow probabilities for over 2" are fairly low over the TX/OK Panhandles, but this should area continue to be monitored. The wrap around banding is likely to continue into the central Plains Monday night, but the occluded low may allow the snow bands to weaken enough to limit the heavy snow threat for Tuesday night. ...Northern Plains through the Upper Midwest... Days 2/3... A northern stream shortwave trough pushing east along the Plains portion of the U.S./Canadian border tonight through Monday night. Increasing moisture as the system shifts east allows warm air advection snow to develop Monday over ND/northern MN that enhances and stalls Tuesday/Tuesday night over northern MN as the southern stream system moves up the Plains, interacting with the northern stream. The Arrowhead of MN looks to have long-fused snowfall with some enhancement off Lake Superior. Days 2.5 and 3 snow probabilities for over 4" are generally low over eastern ND and northern MN, increasing on Day 3 over the Arrowhead where probabilities are moderate. Ahead of this wave from the northern Plains and north of a warm front is a stripe of precip and a potential freezing rain threat that develops near Duluth late tonight and expands over the Upper Great Lakes through Tuesday with potential to linger into or through Wednesday as the occluded low develops to the south over the Midwest. Days 2 and 3 ice probabilities for over 0.1" are moderate near Duluth and low for portions of northern WI/MI. Jackson