Area Forecast Discussion
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
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843 FXUS65 KBOU 300538 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 1138 PM MDT Mon Apr 29 2024 .KEY MESSAGES... - Quick showers northern mountains late tonight. - Cooler Wednesday night and Thursday with a chance of showers. && .UPDATE... Issued at 912 PM MDT Mon Apr 29 2024 Quiet weather across northeast Colorado early this evening. A weak disturbance is still on track to bring a little wave of rain and snow showers across the higher terrain overnight. Made some minor adjustments to the precipitation probability grids. The highest chances will be in the overnight period. Dry, subsident air builds in by tomorrow afternoon shutting down shower activity. && .SHORT TERM /Through Tuesday/... Issued at 315 PM MDT Mon Apr 29 2024 Satellite imagery shows surface heating has produced a nice cumulus field across the plains. Under today`s weak ridging, temperatures have reached the mid to high 60s across the plains and foothills, and the mountains aren`t far behind having reached the 50s. Winds are generally light across the forecast area with some occasional gusts reaching up to 25 kts mainly in the foothills of Boulder County. Tonight will bring some snow showers to the northern Colorado Rockies as an upper level low tracks eastward across Montana. The passing disturbance will usher in just enough Pacific moisture, PVA, and a jet streak overhead to create enough forcing for Jackson, Grand, and Larimer Counties mountains to see some rain and snow showers, and with enough instability present, a chance for a thunderstorm. A cold front associated with the passing disturbance will pass through from northwest to southeast somewhere between 9Z and 12Z Tuesday morning, extending the precipitation and transitioning winds to northwesterly in its wake. All snow and rain showers are expected to diminish by late morning. High temperatures will feel little impact from the passing front aside from being a few degrees cooler than today`s. Cross sections indicate a mountain wave developing in the morning hours. Gusty westerly winds will develop over the mountains, foothills, and portions of the plains that could gust 30-40 mph at times. && .LONG TERM /Tuesday night through Monday/... Issued at 315 PM MDT Mon Apr 29 2024 The next in a series of shortwave troughs will move across Wednesday afternoon and evening. It`s a quick shot, but there`s enough moisture and instability for a pretty good chance of showers and thunderstorms as the trough passes. Ahead of the trough, it still looks pretty warm for the plains during the day Wednesday. Temperatures drop behind the front, although quick drying and subsidence in its wake should provide lots of sunshine on Thursday. We lowered Thursday morning`s lows a little in line with the latest guidance, then Thursday`s highs look alright, mainly in the 50s at lower elevations. We had been expecting some diurnal shower activity Thursday afternoon, but this is looking more questionable with the amount of drying now in the models so we trimmed the PoPs back a bit more. There`s reasonable agreement on another shortwave trough about Friday night. Once again, there should be enough moisture and instability for a quick shot of showers. Less agreement after that. Most model runs have WSW flow possibly becoming more SW into early next week, some with a shortwave going north of us. This is a generally warmer and drier pattern, at least through Monday. We`re a bit surprised the NBM is still dry Monday given some model runs showing either a large upstream trough nearing or a shortwave passing over Colorado. Apparently not enough members and/or a pretty dry environment by then. We left it for now, but this may be a case of the NBM favoring GFS solutions over mainly cooler and possibly wetter EC solutions. We`ll revisit this tonight and tomorrow. && .AVIATION /06Z TAFS through 06Z Wednesday/... Issued at 1138 PM MDT Mon Apr 29 2024 VFR to prevail through Tuesday under scattered to broken mid and high clouds. Southerly drainage winds will continue through about 12Z. Then a weak cold front pushes through and causes winds to turn to the north. Wind direction gets tricky 14-18Z as winds transition from a post frontal north to northeast direction to stronger westerly winds mixing down. Strongest winds are expected to be in the 18Z to 21Z period with gusts to 25 knots possible. Winds then decrease and turn clockwise, becoming and east to northeast direction after 00Z Wednesday. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Mensch SHORT TERM...Bonner LONG TERM...Gimmestad AVIATION...Meier