Marine Weather and Tide Forecast for Lochbuie, CO

SHORT TERM /Through Tonight/
Issued at 233 AM MST Wed Jan 15 2025

Drier air will move across the area today as the flow aloft becomes more NW. However, some shallow moisture will linger over the higher valleys and mtns this morning which may lead to a flurries. Otherwise it will be dry both today and tonight.

As far as highs, will still have to contend with lingering snow cover over portions of the plains. 850-700 mb temps do rise quite a bit today, so highs where no snow cover exits may reach the upper 40s to around 50. In snow covered areas of the plains, highs may stay in the upper 30's to mid 40s. Meanwhile in the higher valleys, where inversions hold, readings will remain below normal.

For tonight the flow aloft will become more WNW with dry conditions over the area. Have lowered temps, in the normal cold areas of the higher valleys, several degrees from guidance.

LONG TERM /Thursday through Tuesday/
Issued at 233 AM MST Wed Jan 15 2025

The axis of a ridge aloft will be over Colorado on Thursday with convergent flow aloft. The substantial subsidence along with downslope winds will allow for quite mild conditions. In fact, some guidance has Denver reaching 63 F which would be just a degree off the record high temperature for the date. But that will be the end of any record high talk for a while. The model guidance that takes Denver to 63 seems to over-mix the westerly, downslope winds so temperatures that warm may be tough to come by. However, highs reaching 60 or 61 will certainly be possible across much of the Denver metro. The only other thing to note for late Thursday and into Thursday night will be windy conditions in the Front Range mountains and foothills as a mountain wave sets up. This event will not be particularly strong and gusts up to 55 mph are possible.

A positively tilted trough will move out of Canada and into the Midwest and High Plains on Friday. This trough will accompanied by a strong cold front that will take temperatures from near record highs on Thursday to below zero by Saturday night. Compared to the past few model runs, there have been some trends with the newest runs.
Previous runs had a stronger surface low pressure system that moves from southeast Colorado across the Red River. At 700 mb on previous runs, there was a stronger trough over northern New Mexico which kept winds more north-northeasterly which would have resulted in better upslope flow for portions of our forecast area. However, the newest runs keep the surface low and the 700 mb low weaker and winds shift towards the northwest quicker during the day on Saturday. Therefore, forecast snow amounts have come down slightly. Ensemble guidance overwhelmingly shows that roughly 0.2" of QPF is forecast for the Denver metro and the forecast is in line with those amounts through Saturday evening. Snow ratios are still expected to by quite high as a large isothermal layer will exist with temperatures in the dendritic growth zone. So we will maximize the QPF with 15-20:1 snow ratios but unless the QPF increases substantially, most snowfall amounts will be in the light to moderate range (2-6") across the I-25 corridor. Higher snow amounts will fall in the Front Range mountains and foothills as better orographic flow will help to increase QPF there.

The cold air associated with the first cold front does not appear to be as cold as once feared. Nonetheless, the low temperatures across the entire forecast area are expected to be below zero with -1 to -5 F forecast across the I-25 corridor and plains.
Northerly winds will be strong enough (gusts up to 25 mph) to allow winds chills to get as low as -20 F Saturday night and Sunday morning.

Another significant model trend was towards a much more amplified secondary shortwave trough. This initially allows Sunday to be warmer than previously forecast as easterly winds impede the progress of the arctic airmass for a short time. There will be light low level upslope, easterly winds across all of the plains on Sunday. Meanwhile, QG ascent will develop aloft ahead of the secondary shortwave trough. The combination of these factors will allow for good coverage of light snow across our forecast area.
Ensembles seem to have caught onto this secondary system as nearly every member of the ECMWF ensembles has accumulating snow in Denver on Sunday. The NBM PoPs include old model data that have a much weaker second system so PoPs were increased on Sunday and Sunday night. The ensemble mean for QPF in the Denver metro is roughly a tenth of an inch so it is reasonable to think another 1-4" might fall during this event with higher amounts in the Front Range mountains and foothills.

Models then bring in the worst of the arctic air after this second system and associated cold front. Lows are currently forecast to be between -5 to -10 F across the I-25 corridor and plains Sunday night. The pressure gradient at the surface will still be strong enough such that wind gusts could reach 20-25 mph. This would allow wind chills to reach as low as -30 F and extreme cold highlights will likely be needed. The peak of the cold airmass will be positioned over Colorado during the day on Monday and highs could struggle to get above 0 F across the I-25 corridor and eastern plains. On Monday night, temperatures will have a chance to bottom out. A high pressure system will be directly overhead so very light winds are forecast. With the fresh snowpack and clear skies, temperatures could reach -15 to -20 F before drainage winds develop and increase temperatures. Temperatures will warm up very quickly on Tuesday as westerly winds with warm air advection develops at 700mb.

AVIATION /12Z TAFS through 12Z Thursday/
Issued at 415 AM MST Wed Jan 15 2025

VFR conditions today thru tonight. Winds were SSW early this morning and should remain so thru early aftn. Still not sure about directions between 20z and 00z. Some data suggest winds may go briefly north for a few hours this aftn while other data has directions remaining SSW. At this point have kept the directions from the SSW. Tonight winds will be SSW thru 12z Thu.

BOU WATCHES/WARNINGS/ADVISORIES
None.