Area Forecast Discussion
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
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656 FXUS65 KBOU 070258 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 758 PM MST Wed Nov 6 2024 .KEY MESSAGES... - Road conditions may worsen after sunset due to cooling pavement temperatures and continuing light to moderate snowfall. - Snow slowly decreases this evening, with a lull/break in snow late tonight. - Next wave of snow arrives Thursday morning, heaviest south of I-70 and east of I-25. - Another shot of snow Friday into Saturday as the upper low tracks northward across the region. Warm enough for rain across the lower plains. && .UPDATE... Issued at 751 PM MST Wed Nov 6 2024 Current radar shows light snow showers remain across the plains this evening. The current forecast still aligns with the latest guidance outputs, leaving little need for updating. Have included the latest observations and will let the current forecast ride for this update package. Conditions have improved over the northeastern plains that have allowed us to expire the Winter Weather Advisory a little ahead of schedule. There may still be some light lingering snow showers, but not worthy of an advisory any longer. && .SHORT TERM /Through Thursday/... Issued at 253 PM MST Wed Nov 6 2024 Snow is still going strong across parts of the Denver area and eastern plains. The strong upper level low spinning along the Colorado/Utah border has been slow to drift south, helping to keep lift over the area longer. Water vapor satellite imagery also showing broad divergence aloft. The heaviest snow seems to be along convergence at 700mb. The 700mb trough weakens overnight bringing most of the snow to an end this evening north of I-70. However, water vapor satellite imagery shows a conveyor belt of moisture still headed this way, so the lull in snow is expected to be short lived tonight and may not totally end south of I-70. As far as the Winter Storm Warnings and Winter Weather Advisories go, the southern foothills and Denver metro area advisories will expire at 06Z Thursday and the eastern plains warnings and advisories expire at 12Z. Hopefully these can be canceled sooner, but with this storm over performing decided not to move up the expiration times. We did make changes and extended the Palmer Divide, Elbert and Lincoln Counties through Thursday afternoon (See below for details). Next short wave and shot of snow lifts northward into the area early Thursday morning. Heaviest snowfall amounts with this will be east of I-25 and south of I-70. We upgraded all of Lincoln County to a Winter Storm Warning until 00Z Friday. An additional 5 to 9 inches of snow is expected Thursday. Winds will be much weaker with blowing snow much less of a concern. We also have a Winter Weather Advisory for the Palmer Divide until 00Z Friday for 2 to 6 inches of new snowfall. The Denver metro area and the eastern plains will see additional snowfall Thursday as well. The snowfall will range from very little north of the Denver metro to a few inches across the southern metro area. && .LONG TERM /Thursday night through Wednesday/... Issued at 253 PM MST Wed Nov 6 2024 It`s looking like a very active weather pattern for the start of the forecast period as a potent storm system ejects from the Desert Southwest into the Central Plains States. Latest models are in good agreement with the track of the upper low with some differences with precipitation and snowfall amounts. Thursday night, the large 500 MB cut-off low will be drifting across Southern New Mexico with light east to southeasterly flow aloft over the CWA. Mostly cloudy skies are expected across the forecast area with some light snow possible across our far southeastern zones due to plenty of low level moisture and some weak QG lift. The models are showing the upper low lifting northeastward through the day on Friday with most of the solutions having it centered near the Southeastern corner of Colorado by Midnight Friday. As the system shifts northeastward, rain and snow should increase across plains as wrap around moisture combines with plenty of QG lift. At this time, it`s looking like snow will ramp up across our far southeastern zones by mid to late morning Friday and spread westward into the Front Range Mountains/Foothills an Urban Corridor by late afternoon. Further to the north, the precipitation may be all rain, or a mixture of rain and snow, due to warmer temperatures. Models are also suggesting quite a bit of isentropic upglide, associated with a TROWAL, which would enhance precipitation and snowfall amounts, especially from the Palmer Divide eastward across the plains. In addition, cross sections are hinting at a possible barrier jet setting up along the Front Range Urban Corridor which could enhance snowfall amounts in these areas as well. Confidence is increasing that several inches of snow will fall from the Palmer Divide eastward across portions of the plains from Friday into Saturday with winter driving conditions expected. However, there is still quite a bit of uncertainty in the forecast, especially across the Front Range Foothills, and portions of the Front Range Urban Corridor. This storm bears watching as minor changes in the storm track could have a significant effect in QPF and snowfall totals as well as travel impacts. Winter Storm Watches my be needed in later forecast packages; therefore stay tuned. Warmer and drier weather is expected across the region by Sunday as the upper low moves into the Upper Midwest. Cooler unsettled weather is expected to return late Tuesday into Wednesday as the next storm system moves into Colorado from the west. && .AVIATION /00Z TAFS through 00Z Friday/... Issued at 453 PM MST Wed Nov 6 2024 Snow showers have persisted this evening that have kept visibility below 2SM for KDEN and KAPA. These showers are expected to decrease in coverage, and visibilities improve in the next hour or so. We are expecting a lull in snow showers for the overnight hours beginning around the 4/5Z timeframe. Decreasing visibility to 2SM and returning snow showers are expected Thursday morning when the next wave of our winter storm arrives. Snow is expected to continue through the day at all TAF sites with decreased visibility to 1.5 SM with the heaviest snowfall in the late afternoon. && .BOU WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 11 PM MST this evening for COZ036- 039-040. Winter Weather Advisory until 5 PM MST Thursday for COZ041. Winter Storm Warning until 5 AM MST Thursday for COZ045-049. Winter Storm Warning until 5 PM MST Thursday for COZ046-047. && $$ UPDATE...Bonner SHORT TERM...Meier LONG TERM...JK AVIATION...Bonner