Area Forecast Discussion
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
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197 FXUS65 KBOU 252006 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 206 PM MDT Wed Sep 25 2024 .KEY MESSAGES... - Warm and dry for the foreseeable future with very limited chances of precipitation. The mountains have a 10-20% chance of showers late Friday into Saturday. - Record highs possible on Thursday and Sunday. && .SHORT TERM /Through Thursday/... Issued at 201 PM MDT Wed Sep 25 2024 Recent satellite imagery reveals clear skies abound across the region, setting the stage for tranquil weather as high pressure dominates the short term forecast period. Another calm and cool night is on tap for the CWA tonight. Temperatures will be a few degrees warmer than last night as northerly flow aloft transitions to a more westerly component. Temperatures are forecast to be in the upper 40s to mid 50s across the plains, with areas at the base of the foothills likely remaining in the 60s. 30s and 40s are forecast for the mountains and high valleys. With an anomalous 500mb ridge overhead and a dry airmass in place, the main highlight for tomorrow`s forecast will be whether Denver reaches 90 degrees or not, possibly tying (or surpassing?) the current record high of 90F, last set on this day in 2010. Conditions look to have high potential as a shortwave passing to the north will temporarily flatten the 500mb ridge centered over the southwest, bringing a westerly downslope component that will nudge temperatures upwards at the base of the Rockies through adiabatic warming. With 700mb temperatures between 15-17C expected, and dry conditions keeping clear skies through the morning, it will be a hot day for the end of September, whether records are met or not. Our persistent clear skies will likely come to an end by tomorrow afternoon as some moisture associated with the passing shortwave makes it under the ridge and forecast cross sections indicate a few clouds forming over the mountains by the afternoon. && .LONG TERM /Thursday night through Wednesday/... Issued at 201 PM MDT Wed Sep 25 2024 A weak and dry cold front Thursday night into early Friday morning will leave very light easterly flow in its wake and provide for a minor relaxation of temperatures as highs fall to the low 80`s for the plains and urban corridor - still well above normal for these dates. Some mid-level moisture may sustain scattered cloud cover, mainly in the mountains, but it will be a very quiet weather day all around. The upper-level ridge will hold strong into the weekend, with slight rises in geopotential heights during this period and large scale subsidence forcing temperatures to rebound to near-record territory by Sunday. Even the high country won`t escape the warmth, with highs peaking 10-15 degrees above average. Increased low-level southeasterly flow later on Sunday could lead to pockets of near-critical fire weather conditions in the plains - arguably the only weather concern of the next several days. Come Monday, a sizable chunk of ensemble members push a cold front southward into Colorado in association with a broad and quite northerly upper-level trough, with substantial cooling and a surge of breezier north winds, but a very slim (~10%) chance for any precipitation. Agreement isn`t consistent however, and WPC clusters indicate at least a 30-40% potential for the ridge to hold in place with the trough taking a more northerly track well into Canada. This would of course retain the anomalous warmth another day. For now, NBM temperatures appear reasonable with moderate cooling behind a front, depicting a blend of both scenarios. With uncertainty in timing, these more seasonal conditions could extend into Tuesday. Guidance actually shows slightly better agreement looking farther ahead, with signs of enhanced ridging once more as we move into Wednesday, bringing a return to well above normal temperatures and keeping the region dry. && .AVIATION /18Z TAFS through 18Z Thursday/... Issued at 1139 AM MDT Wed Sep 25 2024 VFR conditions expected through the TAF period. Light winds are currently making the shift to ESE at all TAF sites where they should remain through the afternoon. Drainage winds are expected overnight before becoming light and variable Thursday morning. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Bonner LONG TERM...Rodriguez AVIATION...Bonner