Marine Weather and Tide Forecast for Byers, CO

DISCUSSION /Through Thursday/
Issued at 257 PM MDT Thu May 22 2025

Main forecast concern will surround thunderstorm chances and intensity as we head into this Memorial Day Weekend.

We still have a chance of a few showers and storms this evening, as we are now getting closer to convective temps (upper 70s).
We're starting to see a little cumulus along a north-south oriented Denver Convergence Vorticity Zone (DCVZ) from around Johnstown to the west side of DIA to near Centennial. Low level moisture has been a little more than earlier advertised, with lower to mid 40s dewpoints on most of the plains. Thus, MLCAPE has been able to increase to over 500 j/kg while CIN is eroding as we continue to warm. Latest ACARS soundings also show us getting close to breaking the cap. Thus, it's not entirely impossible we don't pop a couple strong thunderstorms late this afternoon into early evening. Marginal severe hail and/or a landspout can't be ruled out. Also, a couple storms will be possible near the Wyoming/Nebraska border overnight as a weak shortwave moves across Wyoming - we think the main chance of storms would stay farther north.

On Friday, flat upper level ridging occurs and the thermal ridge shifts east across the state. This will be the warmest day with highs pushing into the lower to mid 80s across the plains.
Southerly low level flow will continue to advection moisture northward across the eastern plains, while a dryline forms along the downslope moving off the Front Range and shifts east. MLCAPE will rise into the 1000-1500 J/kg range where the best combination of heat and moisture exists. Right now, the most likely location for that would be along/east of a Sterling to Akron line, but some chance moisture could hold as far west as Fort Morgan. Anywhere east of that a couple severe storms/supercells are probable (>50% chance) with large hail, damaging winds, and even a tornado threat.

The weather pattern becomes more active this weekend, as an upper level trough, increasing low level moisture, and some upslope all join together. For Saturday, low level moisture is expected to increase further as east/southeast winds develop and advect higher dewpoints across the High Plains. This occurs as surface pressure falls are expected ahead of an upper level trough pushing east across the Great Basin and Northern Rockies. There will be another risk of severe storms, but this time pushing back to the Front Range and I-25 Corridor. That severe threat, however, hinges on the depth of the stratus deck and how much surface heating occurs.
The models have trended cooler which seems reasonable in this pattern, but that doesn't necessarily mean we won't break the cap.
The low levels may be only warming slightly to moist adiabatic, but there's still sufficient MLCAPE and rather strong shear to warrant a risk of severe storms with all hazards possible. SPC outlook is Marginal Risk at this time but considering the time of year, low LCLs, and potential this could get upgraded especially if we can still get MLCAPE of ~1000 J/kg.

Sunday is still shaping up to be the wettest day, as there may be morning showers or light drizzle, replaced by more convective shower and storm coverage in the afternoon. That would occur given a more neutral but moist stability profile (still some weak MLCAPE <600 J/kg). We could even see some locally heavy rain (30-40% chance) if we get a little heating. High temperatures, however, will be quite cool with highs only expected in the lower to mid 60s, and that could be generous if we fill in with a low level stratus deck.

While the trough is still near us for Memorial Day, it is forecast to move east of the forecast area during the day. Thus, as long as it doesn't slow any further we shouldn't see a washout. However, that does bear watching since timing of just a few hours could make a big difference. For now, we'll have a lower chance of showers and storms in line with ensemble guidance. Temperatures will still be below normal, with highs in the 60s expected.

There's not much to change in the expectations for the eventual weather pattern early next week - we'll still be caught somewhere in between a trough to the east and a building ridge/weak zonal flow over the Great Basin or Northern Rockies. This would keep scattered showers and storms in the forecast each day due to lingering moisture in light flow aloft. Temperatures should begin a slow warming trend.

AVIATION /18Z TAFS through 18Z Friday/
Issued at 1213 PM MDT Thu May 22 2025

Forecast is looking on track. Main concern will be winds and possible outflows from a high based shower/storm late this afternoon/evening. Winds have already transitioned to E/SE, but a boundary is lurking just to the west of KDEN that will need to be monitored. We do think it eventually backs to the west through 00Z with increased mixing, but a small chance the boundary stalls very close to the west side of the KDEN field. Robust SE-S winds will then carry into the overnight period, with potential for gusts 22-30 kts between 22Z and 10Z. Isolated high based virga or even -SHRA will be possible 22Z-02Z, and may produce (20% chance)
of slightly gustier winds. Winds will be considerably weaker west of I-25 (e.g. KBJC). Winds will weaken 09Z-12Z Friday, and then turn clockwise through 18Z. VFR conditions will prevail for all terminals through the TAF period.

BOU WATCHES/WARNINGS/ADVISORIES
None.