669 FXUS65 KPUB 301044 AFDPUB Area Forecast Discussion National Weather Service Pueblo CO 344 AM MST Thu Nov 30 2023 .SHORT TERM...(Today and tonight) Issued at 343 AM MST Thu Nov 30 2023 Key Messages: - Snow to develop across the higher terrain, and especially along the Continental Divide, this morning and continue through the day. Currently...Upper low pressure system was moving across AZ early this morning, pushing increasing cloud cover up into southern CO. Most sites were still lingering in the 20s to around 30 degrees as of 3 AM, but the San Luis Valley had dropped down into the 5 to 15 degree range. A weak cold front was pushing south across the Palmer Divide and into the eastern plains. Today and tonight...The weak cold front will continue pushing across the plains, swinging surface winds around to an easterly direction through the morning. This will force a significant drop in afternoon high temps as compared to yesterday, which will be 5 to 10 degrees cooler for the high valleys, and 15 to 20 degrees cooler for the plains. At the same time, the upper low pressure system currently over AZ will track east across NM during the day, then eject to the east-northeast across the Panhandles and into Kansas this evening. As it exits, a larger more significant trough of low pressure will then push into the Great Basin. What this will mean for southern CO will be developing snow across the Eastern San Juan Mts this morning, which will gradually increase in intensity as well as spread to the remainder of the Continental Divide as well as the Sangre de Cristos. Pikes Peak and the Wet Mts should remain dry through the short term. The rest of the forecast area will see increasing cloud cover as well as a lowering cloud deck through the day. The ongoing Winter Weather Advisory for the Eastern San Juan Mts looks good, as latest model guidance is painting a very good probability (70-90%) of the area receiving 8 to 10 inches of new snow, with locally higher amounts. Snow is expected to begin by 18z and there was the temptation of starting the advisory earlier, but the greater snow amounts will likely hold off until this evening so decided against any timing changes. Prepare for highs today in the upper 30s to mid 40s for most locations, and overnight lows of 15 to 25 degrees. The heart of the San Luis Valley as well as the Wet Mt Valley will likely drop to around 10F. Moore .LONG TERM...(Friday through Wednesday) Issued at 343 AM MST Thu Nov 30 2023 Key Messages - Significant snow likely for Continental Divide Region, especially Eastern San Juan Mountains. - Warming trend next week. .Friday through Sunday...Main trough moves over the region on Friday. Southwest flow ahead of the trough is most favorable for heaviest snow in the Eastern San Juan Mountains. Currently have winter weather advisory in effect for the region which looks good. Heaviest snow will be on Friday as the main trough passes over the region. On Saturday, next disturbance passes over the region with the flow aloft being mainly from the northwest. Ensemble means are stingy with QPF over all of the mountains and the northwest flow aloft does not favor the Eastern San Juan Mountains. The advisory for the Eastern San Juan Mountains ends at 0600 UTC Saturday which looks reasonable. On Sunday, flow aloft becomes more northwesterly. There could be periods of light to moderate snow Sunday over the mountains of Lake and Chaffee Counties, and suspect accumulations will be below criteria for an advisory. Even the 90th percentiles for QPF would not support an advisory. Further east, some snow may reach the Sangre de Cristo Mountains where a couple inches are possible. Elsewhere, westerly flow aloft will limit the the QPF. A few snow showers may move across the plains as the troughs pass, but QPF will be limited. With cooler air aloft, temperatures will be cooler than the previous days, and the much colder arctic air will stay will to the north of the region. .Monday through Wednesday...Upper ridge builds into the region for a warming and drying trend. Some light snow will continue over the mountains of Lake and Chaffee Counties on Monday. Otherwise it will be dry and mild. Wednesday looks to be the warmest day of the period with models showing 700mb temperatures around +8C. --PGW-- && .AVIATION...(For the 12Z TAFS through 12Z Friday morning) Issued at 343 AM MST Thu Nov 30 2023 KCOS and KPUB: VFR conditions are expected along the I-25 Corridor and eastward over the next 24 hrs, including the TAF sites of KCOS and KPUB. A weak cold front pushing across the plains early this morning will swing sfc winds around from a N to NE direction to an E to SE direction at 10-15 kts by midday. Plan on gradually lowering CIGS to 080-100 after 00z. KALS: For all of the higher terrain and high valleys, including the TAF site of KALS, plan on worsening conditions through the day as snow begins along the CONTDVD between 12z-15z and CIGS begin to lower over the remainder of the higher terrain. VFR conditions currently will become MVFR/IFR over mt passes by 18z. Conditions at KALS will remain VFR through 00z, then lowering CIGS to 060-080 and snow showers in the vicinity will produce intermittent MVFR conditions after 00z. && .PUB WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 5 PM this afternoon to 11 PM MST Friday for COZ068. && $$ SHORT TERM...MOORE LONG TERM...PGW AVIATION...MOORE