Marine Weather and Tide Forecast for Nunn, CO

SHORT TERM /Through Friday/
Issued at 147 PM MDT Thu Apr 24 2025

Southwest flow aloft will prevail while an east-southeast low level flow advects moisture into eastern Colorado. This has resulted in mostly cloudy skies and cool temperatures over most of the eastern plains with a stable airmass in place. The increase in moisture made it to the urban corridor with dew points in the 40s. Skies were mostly sunny this morning allowing temperatures to reach the mid 60s to lower 70s. RAP model continues to show MLCAPE of 1000-1500 (J/kg) across the urban corridor and nearby plains. A cyclone has formed over the south part of the Denver area. Along this convergent boundary we are seeing towering cumulus and should see storms form along it by mid afternoon.
Additional storm development is expected over the northern urban corridor mid to late afternoon. Large hail, up to golfball size will be the main threat. Isolated wind gusts to 60 mph and a brief tornado will also be possible. Storms will weaken as they head into a less unstable airmass over the eastern plains.

The threat for severe storms will end early to mid evening as the airmass stabilizes. However the chance for showers and thunderstorms will continue through the evening, mainly over northern Colorado behind a cold front pushing south into the area.
Showers and storms end by midnight as the colder air behind the front stabilizes the airmass. Moisture and colder air moving into northeast Colorado will saturate the airmass leading to low clouds, fog, and drizzle after midnight and into Friday morning.

Easterly low level flow will keep low clouds with areas of fog and drizzle going for much of Friday morning, and perhaps into the afternoon in and near the foothills due to upslope flow. Highs will be chilly with upper 40s to lower 50s across northeast Colorado. This will stabilize the airmass over the foothills and eastward. The mountains become slightly unstable with MLCAPE climbing to 500 (J/kg). This is expected to lead to widely scattered showers and thunderstorms over the mountains. As the convective tracks eastward and encounters the cool and stable airmass, the showers and storms are expected to dissipate.

LONG TERM /Friday night through Thursday/
Issued at 147 PM MDT Thu Apr 24 2025

Broad but relatively weak southwesterly flow aloft will overspread the region on Saturday ahead of a closed upper low moving into California, entraining enough mid-level moisture in the afternoon to support isolated to scattered afternoon showers/thunderstorms, generally favoring the higher terrain. At the surface, healthy southerly winds will promote ample warm advection, returning temperatures to above normal values region- wide.

As the low lifts northeast through the Great Basin, southwest flow along its leading edge will increase into Sunday, helping to push highs potentially into the 80's for the lower elevations, with limited change for the high country. Precipitation chances will be buffered substantially under much drier low-levels.
There's growing confidence in critical fire weather conditions across a broad portion of the forecast area for Sunday afternoon, particularly the southern half where humidity will be lowest.

By Monday, the primary low is slated to transition into more of an open wave, with a secondary low shearing off the southern tip of the trough. It's a messy pattern which inherently carries greater uncertainty as far as how things play out through the week, but for Monday we'll at least be looking at considerably cooler temperatures following a frontal passage and greater afternoon precipitation potential, most pronounced in the mountains. Our southern plains could hold onto some fire weather concerns too depending on the frontal timing.

Details are fuzzier Tuesday onwards, with general west to northwest flow prevailing aloft and potentially punctuated by a few shortwaves and opportunities for spring-like convection most afternoons, albeit there are no strong signals.

AVIATION
(18Z TAFS through 18Z Friday)
Issued at 1151 AM MDT Thu Apr 24 2025

Scattered thunderstorms are expected to form after 19Z and then track eastward. Best chance for a thunderstorm at DEN will be 20Z to 23Z. Hail (possibly large 1.75 (in) diameter) will be the main threat with the stronger storms. Outflow winds to 30 knots will be possible as well, with a slight chance at wind gusts over 40 knots.

Cold front pushes south through the Denver area 02-04Z, bringing northeast winds and increasing low level moisture. Scattered showers and isolated thunderstorms will be possible behind the front for a brief period of time. Low clouds form behind the front with ceilings falling below 1000 feet after 06Z. Visibility will likely be reduced to 1sm to 3sm due to the low clouds and drizzle.
Dense fog will also be possible towards 12Z with visibility at or below 1/4sm. The low clouds and reduced visibility will linger most/all of Friday morning with ceilings slowly rising after 18Z.

BOU WATCHES/WARNINGS/ADVISORIES
None.