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938 FXUS65 KBOU 220910 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 310 AM MDT Wed Apr 22 2026 .KEY MESSAGES... - Critical fire weather conditions and potential for rapid wildfire spread today due to gusty winds and very low humidity. Elevated to critical conditions expected on Thursday. - Dry and unseasonably warm weather continues today. Highs will be nearly 20 degrees above normal. - Slight mountain wave amplification to bring strong winds to the higher foothills (mainly above 8,500 feet) Thursday morning. - Pattern change to cooler and unsettled weather by this upcoming weekend. && .UPDATE... Issued at 306 AM MDT Wed Apr 22 2026 Made some minor adjustments to temps and winds. Not sure about tstm threat over the far northeast plains this aftn. Low level moisture looks to mix out by mid aftn with no defined convergence zone. However, can`t completely rule out an isold high based storm with gusty winds due to decent DCAPE. && .DISCUSSION /Through Tuesday/... Issued at 1127 PM MDT Tue Apr 21 2026 Hot, dry, and windy will be the name of the game today as southwest flow increases across the forecast area ahead of an approaching trough currently moving across the Great Basin. Our latest warming trend will max out this afternoon as highs are expected to climb into the 80s once again across the plains, and 60s for our high mountain valleys before returning to near seasonal norms through Saturday. Critical fire weather is expected across the majority of the forecast area by late morning as enhanced downslope winds, drying, and warming is brought on by a deepening lee surface trough. A prolonged period Red Flag Warning is in effect beginning at 10 AM Wednesday morning through Midnight tonight as continued enhanced downslope winds will make for slow relative humidity recoveries. Overall, expecting southwest winds to gust between 30-45 mph (strongest in the afternoon hours when mixing is greatest) with very low relative humidity values in the low single digits across the plains and South Park. This will make for rapid fire spread if a fire were to start. Outside of the fire weather concerns, our northeast corner may see a few late day/evening thunderstorms as a dryline retrogrades westward nudging 50-55 degree dewpoints up against our Nebraska and Kansas borders. The SPC has kept Sedgwick and Phillips Counties in a Marginal Risk for tomorrow for if we do see a storm develop, large hail and strong winds would be the main hazards, though most CAMs show the main activity staying just east and north of our CWA boundaries. A cold front is expected to slide across the forecast area Wednesday night. Additionally, a restrengthening of 700mb flow is expected late Wed night/early Thurs morning as a 60-70kt jet max straddles the WY/CO border. This will increase winds at ridgetop, and while pressure gradients are in place (~10 mb difference between GJT-DEN), the main ingredients we look for in a high wind type mountain wave event, aren`t quite adding up to more than a slim chance that mountain wave amplification will be suffice to send stronger winds down into the lower foothills. We are expecting some stronger gusts to make their way down into our typical upper-foothill windy spots for a few hours early Thursday morning where 55-60 mph gusts will be possible between roughly 6AM to 9AM. With the aforementioned poor overnight relative humidity recoveries expected for our lower elevations and South Park, another critical fire weather day is on tap for Thursday. Despite seeing much cooler temperatures behind the front, windy conditions are expected to persist as subsidence and efficient mixing will keep enhanced winds in place with relative humidities ranging from 10% to 17% across the lower elevations on Thursday afternoon. A Fire Weather Watch is in effect for all of the lower elevations from 10AM to 8PM and will likely be upgraded later today. By Friday, fire weather conditions should start to improve as a backdoor cold front stemming from a building surface high over South Dakota and Nebraska looks to bring improved RH into at least the northeastern plains, but just how far west it makes it could determine the need for any additional fire weather highlights. At this time, confidence is higher in South Park, the Palmer Divide and our southern plains being the likeliest to see elevated to critical fire weather conditions, but would like to wait for the hi-res guidance to come into play before making any decisions. With an upper-level low progged to sit over Southern Canada through the weekend, smaller scale disturbances are expected to move through the larger scale flow keeping at least some potential for light precipitation across the forecast area through the weekend. Sunday looks to be our best shot at any real measurable precipitation as a shortwave brings Pacific moisture into the Rockies, but we will have to see how things trend between now and then. && .AVIATION /06Z TAFS through 06Z Thursday/... Issued at 1120 PM MDT Tue Apr 21 2026 Winds were gusty out of the south at DIA but should decrease by 07z. Otherwise winds will be drainage overnight. SSW winds will increase in the 15z to 16z period with gusts up to 25 mph. SSW winds will continue thru the aftn with gusts from 30 to 35 mph at times. The winds will switch to a more westerly direction by 01z with gusts up to 30 mph thru early Wed evening. Finally, VFR conditions will continue thru the period. && .FIRE WEATHER... Issued at 1127 PM MDT Tue Apr 21 2026 Critical fire weather conditions are expected today as gusty southwest winds and very low relative humidity values coincide across our lower elevations, Front Range Foothills, and South Park. 30-45 mph gusts are expected during peak heating this afternoon, though critical thresholds are expected to be met early and persist through late tonight, therefore, a prolonged Red Flag Warning is in place from 10 AM this morning to Midnight tonight. Poor overnight recoveries are expected tonight that will bring another day of critical fire weather conditions to the same locations on Thursday. Currently these areas are under a Fire Weather Watch, but this is expected to be upgraded to a Red Flag Warning later today. There are uncertainties with how widespread critical fire weather conditions will be on Friday as a backdoor cold front should allow for cooler temperatures and higher RH to filter into the plains through the day. Confidence is higher in critical fire weather conditions developing for South Park, the Palmer Divide, and Lincoln County at this time, but will need to see how things trend as hi-res guidance comes into play today. && .BOU WATCHES/WARNINGS/ADVISORIES... Red Flag Warning from 10 AM this morning to midnight MDT tonight for COZ214>216-238>251. Fire Weather Watch from Thursday morning through Thursday evening for COZ214-216-238>251. && $$ UPDATE...RPK DISCUSSION...9 AVIATION...RPK FIRE WEATHER...9