FXUS65 KBOU 151149 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 549 AM MDT Wed Apr 15 2026 .KEY MESSAGES... - Drier today with mild temperatures. - Locally critical fire weather conditions over the plains Thursday afternoon. - Next system moves in Friday with much colder temperatures and snow for most locations. - Hard freeze likely Friday night and into Saturday morning with lows in the upper teens to mid 20s. && .DISCUSSION /Through Tuesday/... Issued at 1145 PM MDT Tue Apr 14 2026 Satellite and RAP analysis products show today's shortwave continuing to push eastward, with only a few lingering showers across the plains left on radar. Wednesday should be warmer and drier across the forecast area as weak zonal flow develops behind the departing trough. Mid-level temperatures should warm several degC and forecast highs return to the 60s across most of the plains. A little bit of moisture is expected to linger across the high country leading to a bit more cloud cover there, with mostly sunny skies across the plains. Thursday will likely be the warmest day of the work week this week, with southwesterly flow aloft increasing ahead of our next (stronger) trough axis. Temperatures are expected to warm up into the mid to upper 70s across most of the plains... and combined with low relative humidity values... another day of widespread elevated to critical fire weather conditions will be possible. See the Fire Wx section below for additional details. The focus of the forecast period continues to be Thursday night through Friday night, as a strong trough axis swings across the region. Tonight's guidance hasn't changed significantly with the synoptic scale details of this event, with the trough axis quickly pushing across the state during the day Friday. A rather strong cold front looks like it will push into the plains late Thursday night or sometime Friday morning, with 700mb temperatures dropping to as cold as -8 to -11C by Friday afternoon. While the trough is rather quick to move across the region, there would still be a narrow period (<12 hours) of favorable upslope and QG ascent to work with during the day Friday. Unsurprisingly, ensemble guidance strongly favors a modest (around 0.15-0.4") QPF forecast which would lead to generally light snow amounts across most of the Front Range and I-25 corridor. We'll continue to watch trends closely here as we get into the range of the HRRR/RRFS and other CAMs. A cold overnight is likely on Friday night with a hard freeze expected across most of the lower elevations. We may be slow to warm on Saturday, but there's good agreement in a broad ridge developing across the western CONUS by later in the weekend or early next week. Highs should climb to above normal values by Sunday and continue through early/mid-week next week. && .AVIATION /12Z TAFS through 12Z Thursday/... Issued at 549 AM MDT Wed Apr 15 2026 VFR will persist through the TAF period, with only FEW-SCT clouds 10,000 feet AGL or higher. Winds are starting this valid period more westerly than normal, and overall see little change in those winds through about 17-18Z. Weak inversion is in place so sunshine wshould help bring a little more mixing and thus W-NW component 18Z-01Z, before transitioning back to normal S-SW winds by 03Z-05Z Thursday. KBJC will likely see stronger winds with gusts to 30 kts possible this morning due to mountain wave enhancement, but even there winds should settle in speeds this afternoon as flow aloft weakens a bit. Overall, there is higher than normal confidence with those wind trends, although can't totally rule out (20% chance) of brief disruptions in the expected wind progression. && .FIRE WEATHER... Issued at 1145 PM MDT Tue Apr 14 2026 Dry, southwesterly flow aloft is expected to develop on Thursday ahead of Friday's storm system... leading to widespread elevated to critical fire weather conditions across the forecast area. Good agreement across Tuesday afternoon's guidance and from most of the available 00z guidance tonight that we'll see humidity drop to critical thresholds across most of the lower elevations, with some models advertising single digit RH values Thursday afternoon. The bigger question is how much wind will develop across the lower elevations Thursday afternoon. The NBM appears to be far too aggressive with gusts, and even after adjusting down our forecast wind grids are about 5-10 mph stronger than some higher resolution guidance. With mid-level (700mb) flow around 20-25kt, it seems reasonable to expect at least a few hours of >25 mph gusts. Given that the flow is predominantly SW/WSW, much of the I-25/I-76 corridors may be partially sheltered. While many locations in the plains may see critical fire weather conditions, GEFS Hot Dry Windy Index plumes suggest higher confidence of approaching/exceeding the 90th percentile of the HDWI across South Park into Lincoln county, with far more spread along and north of I-70/I-76. For those reasons, we've opted for a relatively small Fire Weather Watch from South Park into the Palmer Divide and adjacent plains for Thursday, though it's possible the day shift will need to make additional refinements after evaluating the full suite of Wednesday's 12z guidance. && .BOU WATCHES/WARNINGS/ADVISORIES... Fire Weather Watch from Thursday morning through Thursday evening for COZ214-216-241-245>247-249. && $$ DISCUSSION...Hiris AVIATION...20 FIRE WEATHER...Hiris