


Area Forecast Discussion
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
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793 FXUS65 KBOU 170527 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 1127 PM MDT Thu Oct 16 2025 .KEY MESSAGES... - Patchy frost tonight for the Palmer Divide, Lincoln County, and portions of Weld County. - Seasonably cool (though slightly milder Sunday), with breezy winds most days through Monday, and limited potential for any precipitation. - Elevated fire weather conditions will be present most afternoons across lower elevations, and may be locally critical come Monday. && .DISCUSSION /Through Thursday/... Issued at 133 PM MDT Thu Oct 16 2025 The closed low now into Wyoming and associated upper-level trough are keeping our region seasonably cool and rather breezy under enhanced southwesterly flow aloft. Temperatures tonight should cool enough under the post-frontal airmass to support patchy frost across some of the lower elevations, with the highest confidence for the Palmer Divide and east into Lincoln County. Opted for a slight expansion of the Frost Advisory into the former as a result. With the shortwave still overhead Friday, temperatures will remain relatively stable, if even slightly cooler in our eastern plains in the absence of warm southerly surface flow. Should otherwise be a mostly clear and dare I say quiet day. By Friday night, stronger synoptic northwest flow will begin to impinge on northern Colorado thanks to an amplifying longwave trough, producing notably stronger winds over the high country initially (gusts 45-55 mph being fairly widespread for higher exposed terrain), then spreading into the plains during the day Saturday behind a secondary cold front. Highs will fall below normal as a result. One advantage of the frontal passage will be an increase in dewpoints and thus humidity, which should limit fire weather concerns despite the breezier conditions. The trough will not dig sufficiently south to bring any meaningful precipitation however, rather just scraping northeast Colorado and limiting the potential for light showers (if any) to our northernmost mountains. Lows at or slightly below freezing look increasingly likely Saturday night/Sunday morning across a majority of the rural plains following the frontal passage (not so much for the urban corridor where downslope flow should taper the cooling), so highlights will eventually be needed barring any significant changes to the forecast. The cooler weather takes a mini hiatus Sunday, as weak ridging briefly expands into the state behind the departing trough. Healthy subsidence accompanying the ridge will make temperatures rebound well into the mid to potentially upper 70`s east of the mountains, and buffer the winds temporarily under weakened flow aloft. Yet another trough enters the picture Monday, following a similar track to Saturday`s. There has been a clear and consistent northward trend in its track over the past 24-48 hours across practically all guidance, including both ensemble and deterministic solutions. Consequently, precipitation chances have almost completely evaporated for our lower elevations, and are now largely confined to our northern mountains. While some light snow remains favored Monday afternoon into Tuesday there, amounts look considerably less impactful. We`ll see if this trend continues. In any case, will need to continue to monitor the potential for locally critical fire weather conditions on Monday, as breezy northwest winds should be relatively widespread. Moisture guidance often lags behind in these situations, so wouldn`t be surprising to see the forecast trend dry enough to meet critical thresholds over time. Beyond that, the pattern transitions to weaker zonal flow, with limited opportunity for precipitation, and temperatures likely quite close to seasonal averages. && .AVIATION /06Z TAFS through 06Z Saturday/... Issued at 1127 PM MDT Thu Oct 16 2025 VFR conditions will persist through Friday night. Winds have settled down in wake of the easterly surge, and a fairly normal transition is now underway that will take winds at KDEN and KAPA from SSE to S to SW through 15Z. There is some uncertainty with winds beyond 15Z, but overall moderate confidence (60-70% chance) that winds eventually become more W-NW-N 17Z-20Z, before an anticyclone develops and winds turn more N-NE-E 21Z-24Z. Even if winds don`t conform to the above, they should stay light and less than 8-10 kts. Then expect a gradual transition to normal S/SW winds by 02Z-04Z this evening. && .BOU WATCHES/WARNINGS/ADVISORIES... Frost Advisory until 8 AM MDT Friday for COZ041>043-046. && $$ DISCUSSION...BRQ AVIATION...20