Area Forecast Discussion
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
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032 FXUS65 KBOU 290536 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 1136 PM MDT Fri Jun 28 2024 .KEY MESSAGES... - Scattered showers and storms could produce gusty conditions until early evening across the mountains to the plains. Expect wind gusts up to 50 mph. A severe storm cannot be ruled for the northeast corner which could produce small hail and wind gusts up to 60 mph. - Isolated to scattered thunderstorms this weekend, with a few strong to severe storms possible Sunday afternoon and evening. - Drier conditions possible by mid next week. && .UPDATE... Issued at 838 PM MDT Fri Jun 28 2024 Scattered showers and storms are currently ongoing across our CWA. The peak intensity of the storms has decreased in the last hour or so due to the lack of daytime heating. For the rest of the evening, gusty winds will be the primary threat as winds could reach 50 mph beneath dying showers. The PoPs were increased through 11pm to get a mention of showers and storms in the forecast. Forecast models and observations would indicate storms will last a bit longer than originally expected. Otherwise, the forecast remains on track with a cold front moving through the eastern plains after midnight. && .SHORT TERM /Through Saturday/... Issued at 242 PM MDT Fri Jun 28 2024 CSU TIME SLICE sounding this afternoon displays weak shear and MLCAPE values near 400-500 J/kg. With large DCAPE values shown on CSU and ACARS soundings between 1000-1400 J/kg, any delayed convection that arrives will bring strong wind gusts up to 50 mph. CAMs favor scattered showers and storms rolling off the foothills into the plains between 4-8 PM MDT. In terms of severe chances, an isolated storm or two could produce wind gusts up to 60 mph and small hail but given our late warm up and dry soundings, the chances are low. Partly cloudy skies clear tonight. A few hours after midnight tonight, a cold front will sweep through the CWA. Northerly winds could produce wind gusts up to 20-30 mph briefly overnight. 700mb temperatures drop between 9-12C as much cooler air approaches from the north Saturday morning. Cold air advection will lead to a afternoon temperatures slightly below normal conditions. Expect low to mid 80s for the urban corridor and plains; low 60s to mid 70s for the mountains, foothills and valleys. Diurnal thunderstorms will develop once more mainly south of I-70 for areas such as South Park, Douglas, Elbert and Lincoln counties. These areas line up with SPC marginal risk of severe storms. With decent conditions for development such as steep mid- level rates between 7-8C/km, 25-30kt shear, and weak instability, it is possible a few storms could produce small hail, and gusty winds. && .LONG TERM /Saturday night through Friday/... Issued at 242 PM MDT Fri Jun 28 2024 Weak ridging aloft and subtle height rises increase mid-level temperatures on Sunday. This will support a rebound in temperatures back into the lower 90s across a good portion of the plains and urban corridor. MLCAPE values are marginal (< 1000 J/kg) with normal to slightly above normal moisture and weak ascent. The higher chances will more likely be in the mountains/foothills, Park County, and the Palmer Divide areas where the higher instability/moisture is. Model soundings across the east plains show sufficient instability, but are weakly capped, which may also thunderstorm development/coverage. Shear will be sufficient to support a few organized strong to severe thunderstorms. Early next week to mid-week, the main axis of an upper level trough positions to the west of Colorado. An upper jet situates to the north, putting CO in an area of weak ascent. Moisture ranges from above to just above average. As a result, each day will feature afternoon/evening chances for scattered, lower coverage thunderstorms with the higher chances for the higher terrain and Palmer Divide. Towards the end of the week, moisture gradually decreases as an upper ridge slowly pushes eastward across the western CONUS. && .AVIATION /06Z TAFS through 06Z Sunday/... Issued at 1129 PM MDT Fri Jun 28 2024 Cold front imminent in next 1-2 hrs for Denver metro, and will bring shift to north winds with gusts up to 20 kts at times. Expect reduction in speeds after 1 to 2 hours post-front, with generally north flow prevailing still. Some low clouds 025-035 may trickle in after ~09Z Sat, but suspect any CIGS would be on the patchier side, with better chances from KDEN eastward into the plains. Any low cloud cover should dissipate near 16-17Z. Winds will be out of the southeast for most of the day tomorrow. Scattered convection will develop mid afternoon, with greater coverage immediately due south of Denver. Leaning on bulk of convection remaining south of KDEN, but do believe stronger TS are possible relative to yesterday, so have replaced VCSH with VCTS or -TSRA in TEMPO (terminal-dependent). Some outflow winds possible (favoring southerly direction), but expect outflow threat to be less than previous days. As convection moves into the southeast plains, more robust south flow will take hold in the evening and overnight, when gusts have a higher potential of exceeding 30 kts. Also monitoring for potential intrusion of low to mid-level cloud cover Saturday night under a moist environment, but confidence is low. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Danielson SHORT TERM...AD LONG TERM...Mensch AVIATION...Rodriguez