Marine Weather and Tide Forecast for Granby, CO

SHORT TERM /Through Saturday/
Issued at 228 PM MDT Fri Apr 18 2025

Deepening moisture and a slight enhancement of the upslope component in the low-level winds will support continued snow across the high country, foothills and urban corridor, gaining some intensity and persistence this afternoon and evening. Despite ambient temperatures near or below freezing around the Denver metro, pavement temperatures remain markedly warm at this hour courtesy of the April sun, effective even with the cloud cover. With increased snowfall rates and roadway temperatures anticipated to drop near freezing between 5-8pm, some slushy accumulations will become possible for the urban corridor this evening, primarily west of I-25 where snow will be heaviest/most persistent. Thus, minor impacts to the very tail end of the commute will be possible, but there just isn't enough road temperature, snowfall intensity, and snowfall duration alignment to necessitate any expansion of current headlines. The extent of travel impacts is similarly questionable for the Palmer Divide, but there's enough potential for snow to drag on longer into the evening for us to retain the Advisory and see how things play out. In the high country, the focus for the heaviest snow will focus along and south of I-70, especially in and around Park County, with hazardous road conditions expected to extend into Saturday.

That being said, one consideration for the overnight period will be the freezing of road surfaces as snow gradually diminishes and temperatures fall below into the 20's, making roads slick early Saturday. Patchy fog can't be ruled out either for the lower elevations in the morning.

For Saturday, we'll see modest warming into the 50's for the plains/urban corridor (low 50's in the northeast corner), and mostly 30's for our mountain communities. Southeasterly low-level flow combined with lingering mid-level moisture will sustain scattered snow showers in the mountains, again favoring I-70 southward, whereas most other areas will be mostly dry past midday. Cloud cover will be slower to clear however.

LONG TERM /Saturday night through Friday/
Issued at 228 PM MDT Fri Apr 18 2025

Saturday night, an upper level trough of low pressure will be over the Rocky Mountain Region with a closed upper low tracking across New Mexico. Cross sections show diminished upslope flow east of the mountains which should result in mostly dry weather across the plains. The high country could see scattered snow showers overnight due to some weak orographic lift combined with QG lift from a passing shortwave.

Warmer and drier weather is expected on Sunday as the upper trough moves into the Central Plains States and a weak upper ridge builds over Colorado.

Early next week, a zonal flow aloft sets up over the state with mild and dry weather across the plains, with temperatures climbing into the lower to mid 70s. Across the high country, there should be enough available moisture combined with some orographic lift to produce isolated to scattered rain and snow showers. On Monday, the flow aloft will be the strongest which will produce breezy conditions across the higher mountains and foothills. In addition, the plains could also see gusty winds due to a downsloping flow. The gusty winds combined with low relative humidity will lead to increasing fire danger during the afternoon hours.

For the Wednesday night through Friday period, the upper flow turns southwesterly in response to an upper level trough deepening along the west coast of the U.S. At the surface, the gradient between higher pressure over the Central U.S. and lower pressure over Colorado should allow east to southeasterly winds to advect higher moisture onto the plains. This moisture combined with daytime heating may lead to a better chance for afternoon and early evening showers and storms through this period.

AVIATION /18Z TAFS through 18Z Saturday/
Issued at 1141 AM MDT Fri Apr 18 2025

Snow will become more persistent through early evening, with vis reducing to 2-4SM most of the time for KAPA and KDEN, and at times 1SM or less possible, especially for KBJC. CIGS will hover between 006-010, with sustained northeast winds near 10kts for the remainder of the day.

SHSN will diminish through the overnight period, although there's some uncertainty as far as just how quickly showers and CIGS will lift. Additionally, there's some potential for lower stratus 10-15Z Sat and FG for Denver terminals, although development of SE winds Sat AM could hamper this, so confidence is relatively low.

BOU WATCHES/WARNINGS/ADVISORIES
Winter Weather Advisory until 6 AM MDT Saturday for COZ031- 033>037-041.