Area Forecast Discussion
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
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519 FXUS65 KBOU 041734 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 1134 AM MDT Thu Jul 4 2024 .KEY MESSAGES... - Quiet weather for the 4th of July, with just a weak stray shower or two this evening - Critical fire weather conditions across Park County this afternoon - Somewhat cool and mainly dry conditions will persist Friday through early next week. - Best chance for showers and storms in the extended will be Sunday. && .UPDATE... Issued at 1027 AM MDT Thu Jul 4 2024 Cooler start to the day today thanks to the passage of a cold front last evening. Temperatures earlier this morning can even be classified as "chilly" in the mountains/valleys with 30s around. Satellite shows a clear picture this morning, blue skies on this Fourth of July. Clouds develop this afternoon. There is a low chance of a stray shower or storm this afternoon/evening in the foothills, northern Larimer and Weld, and the Palmer Divide. No updates needed to the previous forecast. && .SHORT TERM /Through tonight/... Issued at 249 AM MDT Thu Jul 4 2024 Today`s forecast features quiet weather for the first time in several days, much to the relief of this tired midnight shift forecaster. The northeast plains are off to a cool start this (early) morning. The post-frontal airmass did have just enough moisture for some stratus across the southwestern Denver metro, but low cloud cover is slowly diminishing per the GOES Nighttime Microphysics RGB. We should have mostly clear skies by sunrise, and mostly sunny conditions will continue through most of the day today. High temperatures today should remain on the cool side, with upper 70s to low 80s expected across most of the plains. We`ll hold on to some modest surface moisture, and mid-level moisture is also expected to increase slightly during the afternoon and evening hours. However, there`s very little instability to work with and moisture overall is still expected to be below normal across the region. Only an isolated shower or two is forecast this afternoon and evening, primarily over the Front Range Foothills where surface convergence is maximized. Even if these showers form, they aren`t expected to be impactful with very brief/light rain and perhaps briefly gusty winds. A few elevated showers are also possible overnight as modest instability develops across the plains, but models are not very enthused with this potential. The main story of the day will be elevated to critical fire weather conditions across the high country. See the Fire Wx section of the AFD for additional details. && .LONG TERM /Friday through Wednesday/... Issued at 249 AM MDT Thu Jul 4 2024 Friday will be another gorgeous weather day as a weak shortwave trough will move through during the morning hours. This may create a few morning showers across the northern plains but the majority of the area will be dry. By the afternoon, the NVA behind the departing trough will keep any light showers that form limited in coverage and intensity. By Saturday, the flow aloft will turn more westerly ahead of a shortwave trough that will arrive late Saturday night. The more westerly flow will lead to downslope winds and with 700 mb temperatures around 17 C, highs will likely reach the upper 80s to low 90s across the plains. The shortwave trough will continue to move across Colorado Sunday as a cold front moves through the eastern plains. This front will have better moisture behind it and with the QG ascent from the trough, there will be scattered showers and storms that form mainly in the afternoon. The southern foothills and Palmer Divide will be favored for storms due to the northeast low levels winds enhancing upslope flow there. The shortwave trough will move past our forecast area on Monday as slight ridging aloft builds in. This will lead to another gorgeous day as temperatures will remain below normal with plenty of sunshine. An upper level ridge over the west coast of the US will begin moving eastward by the middle of next week. This ridge is already producing an expansive heat wave and it will have a lot of hot air associated with it. The good news is that it will take a while for this ridge to reach Colorado and the global ensembles seemly delay it slightly each run. The bad news is that the slow-moving nature of the ridge will only be able to delay the inevitable for so long. There will eventually be a heat wave in Colorado and ensembles favor that beginning either on Thursday or Friday of next week. && .AVIATION /18Z TAFS through 18Z Friday/... Issued at 1134 AM MDT Thu Jul 4 2024 VFR conditions expected through the TAF period. Light and variable winds become northeasterly this afternoon at 6-10 kts. Mid and high level clouds develop toward early evening. Can`t rule out the low chance of a high-based shower nearby. Light winds overnight and light northeasterly winds again Friday afternoon. && .FIRE WEATHER... Issued at 249 AM MDT Thu Jul 4 2024 Continued dry conditions are forecast tomorrow. Main concern is Park County (Fire Zone 214) where critical fire weather conditions are forecast. RH yesterday fell to around 15% in the afternoon in that zone with some gusts to 30 mph. Forecast guidance is generally a couple of percent lower with humidity and should fall below 14% across most of the zone. Forecast soundings suggest PBL top winds of roughly 25-30kt, and it seems reasonable to expect gusts of 25-35 mph through the afternoon. Therefore we opted for a Red Flag Warning this afternoon. Across the rest of the forecast area, humidity values should remain above critical thresholds. Elevated fire weather conditions are likely across the higher elevations and portions of the plains where breezy winds are forecast. && .BOU WATCHES/WARNINGS/ADVISORIES... Red Flag Warning until 7 PM MDT this evening for COZ214. && $$ UPDATE...Mensch SHORT TERM...Hiris LONG TERM...Danielson AVIATION...Mensch FIRE WEATHER...Hiris