Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 425 PM EDT Fri Apr 01 2022 Valid 00Z Sat Apr 02 2022 - 00Z Tue Apr 05 2022 ...Eastern Great Lakes and Northeast... Days 1-2... An amplified upper level shortwave and its associated surface reflection will continue to move across the Northeast this evening. In addition to some wraparound precipitation spreading across the U.S.-Canada border into northern New England, lake effect showers are expected to continue into the evening hours. Snow is expected to diminish as a shortwave ridge shifts east across the region tonight. Overall, additional heavy accumulations tonight into early tomorrow are not expected. After a brief dry period, precipitation is expected to return the region as another amplified shortwave crosses the region Saturday night into Sunday. Across Upstate New York, thermal profiles support snow initially before changing to a rain/snow mix, especially across the lower elevations. Again, widespread heavy accumulations are not expected. ...Corn Belt... Days 1-3... Two systems will likely affect the region over the next three days. The first will develop tonight as a mid-level shortwave moves through Iowa. At the surface, an area of low pressure will exit Colorado and slip eastward as a brief surge in precipitable water noses into eastern Iowa and southern Wisconsin. Temperatures at the surface will be marginal, near and maybe just above 32F, but CAM guidance continue to suggest a focused area of frontogenesis over the area around 12Z Sat with appreciable lift into the DGZ. WPC snowband tool shows the possibility of >1 inch/hr rates around daybreak which could accumulate a few inches from northeastern Iowa into southern Wisconsin. WPC probabilities have shown a small increase in the chances for accumulations of 2 inches or more across this area. The next system will be on Sunday evening into early Monday. Probabilities for accumulating snow have increased with the latest run across portions of Wisconsin into Lower Michigan, however model spread is still significant with this system, limiting probabilities and forecast confidence. ...Northwest... Days 1-3... A weak system will move through the area tonight with snow levels around 4000ft before falling a bit on Saturday behind the front. By Sunday night, a strong/extended jet (160 kts) across the Pacific will aim into the Northwest coast with a significant moisture flux reaching into western Washington/Oregon. West-southwest flow will capitalize on upslope into the Olympics and Washington Cascades where widespread accumulations of a foot or more are likely, with multiple feet possible across the higher peaks. Lesser amounts are expected into Oregon where snow levels will be higher. ...Colorado/New Mexico Rockies... Day 3... Weak upper trough and surface cold front will lead to an increase in snow over higher elevations of Colorado on Sunday, aided by upslope flow as an area of high pressure sinks southeastward over the Plains. At least a few inches of snow can be expected across the higher elevations of the central Colorado and far northern New Mexico ranges. For Days 1-3, the probability of significant icing of at least 0.25" is less than 10 percent. Pereira/Fracasso