ZCZC SPCSWOMCD ALL ACUS11 KWNS 140239 SPC MCD 140239 NEZ000-COZ000-WYZ000-140845- Mesoscale Discussion 0172 NWS Storm Prediction Center Norman OK 0839 PM CST Sat Mar 13 2021 Areas affected...Eastern Colorado into Wyoming and western Nebraska Concerning...Heavy snow Valid 140239Z - 140845Z SUMMARY...Heavy snow with rates around 1 in/hr will continue periodically through the next several hours. Widespread heavy snow with rates of 1 to 2 in/hour in the Plains, and 3+ in/hr in the foothills/mountains will likely expand in coverage late this evening and overnight. DISCUSSION...*Corrected for Wording* Evening water vapor imagery showed a deep upper-level low atop the Four Corners with a 100 kt 500 mb speed max rotating around the low across the High Plains. Surface low pressure across the Texas Panhandle will gradually intensify and shift northwestward across Kansas through this evening and overnight. A TROWAL signature was also noted to the northeast of the center of the low in response to strong mid-level warm advection occurring to the east. 00Z operational RAOBS and university/research soundings show a deep layer of saturated east northeasterly upslope flow stretching from southeastern Wyoming into northeastern Colorado. This deep orographic lift is supporting moderate to heavy stratiform precipitation along the I-25 corridor. Snowfall rates of 1 in/hour are likely within the heavier bands of precipitation through the next several hours. The most likely location for the heaviest snowfall rates will be along the eastern slopes of the northern Front Range, southern Laramie Range, and the Cheyenne Ridge where orographic enhancement will be maximized. Expansion of the snowfall deeper into the Nebraska panhandle is also expected this evening as nocturnal/dynamic cooling of the column promotes a changeover to all snow this evening. More widespread heavy snow will likely develop after 04z this evening and overnight as the main forcing for ascent from the upper low spreads eastward across Colorado. The TROWAL will move east/southeast centered across northern Colorado and southern Wyoming supporting intense lift and precipitation through the overnight hours. Localized blizzard conditions may develop across portions of northern Colorado and southern Wyoming in response to increasing surface pressure falls from the strengthening lee low across western Kansas. Snowfall rates of 1 to 2 in/hr will be possible across the Plains with very heavy rates of 3+ in/hr possible in the foothills and mountains northwest of Denver. ..Lyons.. 03/14/2021 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...PUB...BOU...CYS...RIW... LAT...LON 42960627 42590650 42260610 41580580 41250575 40840579 40220586 39840601 39570606 39290605 38930600 38720591 38510567 38390542 38360508 38340446 38410401 38410388 38510383 38760373 39020362 40120334 40730326 41270314 41730314 42430326 42790363 42990420 43060514 43060590 42960627 NNNN