MD 2051 CONCERNING HEAVY SNOW FOR THE NORTHERN WASHINGTON CASCADES VICINITY
Mesoscale Discussion 2051 NWS Storm Prediction Center Norman OK 0734 AM CST Tue Dec 20 2022 Areas affected...the northern Washington Cascades vicinity Concerning...Heavy snow Valid 201334Z - 201730Z SUMMARY...Snow rates will continue to increase across the northern Washington Cascades this morning, perhaps maximizing up to 2+ inches per hour around 8-10 AM PST. DISCUSSION...Large-scale ascent is increasing within saturated (or saturating) and subfreezing thermodynamic profiles across the northern Washington Cascades. The lift is being supported by lower/mid- tropospheric warm advection, as southwesterly flow in the 850-700 mb layer strengthens to 50+ kt, in advance of a weak frontal low forecast to migrate inland of the Washington coast this morning. It appears that this will be enhanced by forcing associated with an approaching vigorous mid/upper jet streak, which Rapid Refresh forecast soundings suggests will contribute to maximizing lift in the favorably cold mid-level layers for large dendritic ice crystal growth during the 16-17Z time frame. This may include at least a couple hour period of heavier snow rates on the order of 2+ inches per hour, particularly across the Mt. Baker-Snoqualmie National Forest into North Cascades National Park vicinity, as precipitable water increases in excess of .50 inches. ..Kerr.. 12/20/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...OTX...PDT...SEW... LAT...LON 48092193 48922126 48572039 47532087 47542178 48092193
