Area Forecast Discussion
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
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600 FXUS65 KBOU 061008 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 408 AM MDT Mon May 6 2024 .KEY MESSAGES... - Very active weather pattern through the next couple days, with Winter Weather, Fire Weather, and High Wind highlights in effect - Snow and blowing snow develops across the high country late tonight and continues through Tuesday. Travel impacts likely, especially across the Park Range/Rabbit Ears Pass. - Widespread gusty winds developing tonight and continue through at least Tuesday, with the strongest winds expected across the higher Foothills. - Cool and unsettled weather along with much lighter winds Thursday through Saturday. && .SHORT TERM /Through tonight/... Issued at 407 AM MDT Mon May 6 2024 Snow, wind, fire, and slightly cooler air. These four elements will lead to hazardous weather conditions across northeastern Colorado today. GOES-18 water vapor displays a decent plume of moisture across our mountains this morning. As this trough enters portions of western Colorado, winds aloft shift west increasing between 70-90kts throughout the 500-700mb layer. In fact, vort max pivots along the foothills and areas west of I-25. This will allow for orographic snowfall for elevations above 8 thousand feet to persist which will lead to totals between 3-8 inches through Tuesday. The Winter Weather Advisory will continue through 6 PM this evening; it is likely snow will continue after this time period but intensity should decrease as the trough axis begins to exit. Wind. Similar to yesterday, deep mixing will occur which will maximize surface winds especially along the urban corridor. BUFKIT soundings momentum xfer presents 35-45kts mixing down to the surface well before noon for urban corridor areas west of I-25. Given the strong signals of this bora event, decided it was possible for gusts up to 60 mph to occur for these areas which lead to additional High Wind Warnings through midnight tonight. It is possible these conditions may become spotty reach 60 mph across these zones but given the threat along I-25 on a Monday morning/afternoon commute, it was evident to issue. Additionally, parts of the mountains and foothills will gusts up to 75 mph. Wouldn`t be surprise as the trough passes through, gusts peaking up to 80-85 mph occurring on mountain passes. Tonight, expect westerly winds to continue gusting but decreasing in intensity along the urban corridor and plains. Across the foothills and mountain passes late this evening, wind gusts up to 40-50 mph and low visibilities due to blowing snow proceeds through Tuesday. Fire. Minimum relative humidities this afternoon range between 35-55 percent for areas west of I-25 and slight lower between 20-25 percent for areas east of I-25 outside of southern Lincoln county. Although these areas are not included in a Red Flag Warning, if a fire were to occur, expect rapid spread as westerly winds will produce wind gusts up to 50 mph. Critical conditions are possible for southern Lincoln county this morning through this evening.. see fire weather sections for more. Slightly cooler air. As the trough approaches, 700mb temperatures this morning range between -4C to -2C through late afternoon. With cold air advection passes with the trough, expect afternoon temperatures to sit almost 10 degrees cooler than yesterday. Mountains and valleys range between low 30s to low 40s. Parts of the foothills, urban corridor and plains will reach the mid 40s to upper 50s with a few spots in the northeast corner slightly above 60. Lows remain slightly cooler than normal as well. && .LONG TERM /Tuesday through Sunday/... Issued at 407 AM MDT Mon May 6 2024 An intense storm system will be over the nrn High Plains on Tue with stg WNW flow aloft remaining over the area. Cross-sections show favorable moisture and orographics in the mtns along with lapse rates around 8 c/km. Thus will see another round of snow with advisory amounts likely along with areas of poor visibility due to blowing snow. As far as winds, cross-sections show cross barrier flow won`t be as stg and there is a lack of a mtn wave. So, although it will be windy the threat of winds meeting high wind criteria look low at this time. Across the plains it will be manly dry with another day of gusty winds but speeds should also stay below high wind criteria. Highs on Tue will be in the 60s over nern CO. For Tue night into Wed, the upper level storm system will begin to weaken and move southeast into the central plains. Cross-sections show decreasing moisture in the mtns so snow shower activity will be less in coverage. Across the plains, it will remain mainly dry with lighter winds. Highs will be in the upper 50s to mid 60s over nern CO. Meanwhile, one thing to watch overnight into Wed morning will be the possibility of freezing temperatures over portions of nern CO. By Wed night into Thu, the storm system is fcst to elongate as one piece of energy moves eastward out of the Central Plains while another piece of energy redevelops further west from the central Rockies into the Great Basin. As this occurs, another cool front will move across the area. The combination of these two features may bring a chc of light precip to the area on Thu along with cooler temperatures. Highs across the plains may stay mostly in the 50s. Looking ahead to Fri, there is still alot of uncertainty as to how far west a weak upper low will be located and how much moisture will be across the area. The GFS has a considerable amount of moisture affecting the higher terrain with widespread precip. Meanwhile, the ECMWF keeps this moisture further west with much lower precip chances across the higher terrain. For now, will continue with the blended solutions until it becomes more clear how things will evolve. For next weekend, there are major differences between the ECMWF and GFS in the overall pattern. The ECMWF has a weak closed low moving into the area late Sat into Sun while the GFS has a disturbance in NNW flow aloft moving across on Sat. Overall, the ECMWF solution would bring a good chance of precip to the area on Sun while the GFS generates a good chc of precip on Sat. Once again, confidence in either of these solutions is very low at this time. && .AVIATION /06Z TAFS through 06Z Tuesday/... Issued at 1117 PM MDT Sun May 5 2024 VFR conditions will continue through Tuesday morning. Winds continue in southeast flow until 9-10Z then shifting southwest. Wind speeds increase Monday afternoon gusting between 25-35kts. Westerly winds are expected which may lead to crosswinds issues at KDEN and KAPA. Wind speeds near 20-26kts will likely continue until 02Z at all terminals. By Monday late evening, it is possible wind speed decrease between 14-17kts and shift southwest once more. && .FIRE WEATHER... Issued at 407 AM MDT Mon May 6 2024 A Red Warning is in effect for southern Lincoln county for critical fire weather conditions this morning through this evening as very windy conditions exist across the plains. Relative humidity will drop between 11-15 percent and wind gusts up to 50 mph could occur. Gusty winds and low humidity will continue on Tuesday across the plains with critical fire conditions over southern Lincoln county. Elsewhere across the rest of the plains elevated fire conditions will be in place. && .BOU WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 6 PM MDT this evening for COZ031- 033-034. High Wind Warning until 6 AM MDT Tuesday for COZ035-036. High Wind Warning until midnight MDT tonight for COZ038-039. Red Flag Warning from 9 AM this morning to 9 PM MDT this evening for COZ247. Red Flag Warning from 11 AM to 7 PM MDT Tuesday for COZ247. && $$ SHORT TERM...AD LONG TERM...RPK AVIATION...AD FIRE WEATHER...AD/RPK