National Weather Service Forecast Discussion |
Thornton Weather Forecast Today's Forecast Story |
981 FXUS65 KBOU 182351 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 551 PM MDT Sun Oct 18 2026 .KEY MESSAGES... - Warm and dry conditions continuing into the upcoming week. - A few mountain rain and snow showers early in the week. - A more organized system by late week or next weekend, with light rain/snow showers likelyacross the high country. && .DISCUSSION /Through Sunday/... Issued at 126 PM MDT Sun Oct 18 2026 Water vapor satellite imagery shows two weak upper level troughs to the southwest. The first trough is just south of the Four Corners and the second is near Yuma, Arizona. The first trough passes to our south tonight bringing high clouds. A few weak showers willbe possibleacross southwest Colorado, but nothing is expected in our forecast area. Temperatures will be slightly cooler Monday due to increased cloud cover and slight cooling behind a very weak cold front that backed south across the area today. The central mountains could see isolated rain and snow showers Monday afternoon and evening, otherwise dry conditions will continue. Tuesday will warm a little, and we`ll see a continued chance for isolated showers over the central mountains during the afternoon and evening. An upper level ridge forms over the region Tuesday night and Wednesday ahead of an upper level low along the west coast. We`ll see mild temperatures with highs in the 70s over northeast Colorado and dry conditions across the area. The upper level ridge shifts east of Colorado Wednesday night as the upper level low along the west coast moves inland over California. This will bring a southwest flow aloft to Colorado. The flow extends far enough south to pick up subtropical moisture.On Thursday, the upper level ridge will remain over the middle part of the country. Thiswill cause the upper level low to track northeast across the intermountain west Thursday andFriday. By late Friday the upper level low (in a much weaker state) is expected to be north to northwest of Colorado, somewhere over Wyoming and/or Idaho. Southwest flow aloft and moisture will increase over western Colorado under this pattern on Thursday. Widespread rain and mountain snow are expected over the southwest Colorado mountains. The moisture embedded in the southwestflow aloft is wrung out over the mountains with only scattered showers expected for the north central mountains and dry conditions east of the mountains through Friday. For next weekend, models still vary on solutions, but agree there won`t be much left of the upper level low. There is loose agreement that unorganized troughiness passes eastward across the Rockies, but some models even wash this troughiness out, leaving only westerly flow aloft. Temperatures likely cool closer to normal. Regarding precipitation chances, model spread ranges from dry conditions to a round of light rain and mountain snow showers. && .AVIATION /00Z TAFS through 00Z Tuesday/... Issued at 536 PM MDT Sun Oct 18 2026 VFR conditions to persist through the TAF period. Current easterly winds are expected to become more north-northwesterly through the evening tonight, with KAPA perhaps seeing a brief turn to the southeast first between 2Z-4Z. There may be a few gusts (10-15 kts) with the onset of the north-northeasterly push (better chances at KBJC), but by 8Z-10Z light and variable winds (under 6 kts) are expected across all TAF sites. These light and variable winds are expected to persist through the morning on Monday, becoming easterly between 18-20Z and slightly increasing in magnitude (9-10 kts) after 21Z-22Z. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...BM AVIATION...9