BBS: TELESC.NET.BR Assunto: HVYSNOW: Probabilistic Heavy Snow And Icing Discussion De: COD Weather Processor Data: Tue, 28 Apr 2026 18:13:13 +0000 ----------------------------------------------------------- FOUS11 KWBC 281813 QPFHSD Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 213 PM EDT Tue Apr 28 2026 Valid 00Z Wed Apr 29 2026 - 00Z Sat May 02 2026 ...Central & Southern Rockies... Days 2-3... Two distinct mid-level impulses will interact as they move across the Great Basin and into the Central Rockies to bring heavy snow to the higher elevations of CO and NM. During the past few model runs the trends have been for more substantial snow but with a farther south footprint, with significant accumulations now expected to miss Wyoming, but affect Colorado and New Mexico Wednesday night through Friday night. At the beginning of the period /00Z Wednesday/ these impulses will be positioned over CA, and west of Baja, respectively. Throughout D1, the lead impulse over CA will open and become embedded in the larger trough over the Great Basin, while the stronger impulse (really a cutoff low) will hang back and move little until opening on Thursday as it drifts eastward over Baja. As this secondary evolution occurs, the result will be a longwave positively tilted trough anchored NE to SW across the Central and Southern Rockies, with 500mb heights falling below the 10th percentile within the CFSR database across the Desert Southwest. This evolution will result in broad height falls and the amplification of an impressive subtropical jet streak arching from the Four Corners into the Ohio Valley. Where the LFQ of this jet streak overlaps with the height falls, broad synoptic lift will occur, likely focused over CO and NM. At the same time, since the primary trough axis will lag to the west during this forecast period, persistent SW flow within the 700-500mb layer will transport moisture northeastward, and while the core of the IVT will remain south of the Four Corners, there will be sufficient moisture to result in heavy precipitation. The heaviest precipitation is likely in the upslope regions of the east-facing terrain thanks to easterly flow behind a cold front, but modest fgen and continued mid-level isentropic ascent will also expand precipitation across much of CO and NM by 00Z-06Z Friday. Snow levels through the event will remain elevated, generally around 8000 ft, but may periodically fall to 7000 ft through a combination of precipitation loading/dynamic cooling, lowering heights aloft, and CAA behind the cold front. This will allow for some light accumulations even out onto the Palmer Divide and Raton Mesa. However, the heaviest snowfall is likely in the higher elevations along the Front Range, Sangre de Cristos, and as far west as the San Juans. 2-day WPC probabilities are high for more than 12 inches of snow are high (>70%) in the higher elevations of the Front Range, including the Pike's Peak region, and along the Sangre de Cristos. Lower elevations will have less snow, but I-25 will also likely experience some modest accumulations where it crosses the Palmer Divide and Raton Mesa as reflected by WPC probabilities for 4+ inches in these areas that rise to 30-50%. The probability for significant icing over one-tenth of an inch is less than 10 percent. Weiss $$ = = = To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.28-Linux * Origin: Capitol City Online (1:2320/107) ----------------------------------------------------------- [Voltar]