Area Forecast Discussion
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
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721 FXUS65 KBOU 130956 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 356 AM MDT Thu Jun 13 2024 .KEY MESSAGES... - Much above normal temperatures will continue today. Isolated showers and storms will produce gusty outflow winds in the afternoon and evening hours. - Snowmelt producing minor impacts from high streams, mainly in Grand County. - Slightly cooler conditions will arrive Friday and Saturday with scattered showers and storms. Some of these storms could be strong to severe along the plains with heavy rain on Friday. && .SHORT TERM /Through tonight/... Issued at 355 AM MDT Thu Jun 13 2024 As previously expected, mid level temperatures will be a bit warmer today. However, there`s mid level moisture which will again produce clouds and high-based weak showers. It`s likely there`s a bit more of this than yesterday, which should lead to earlier cloud development. We also have a weak "cold" front that will pass through by midday. This will only bring a few degrees of low level cold advection, but the combination of these two things should offset the warming aloft and result in temperatures similar to, or slightly cooler than yesterday. With better coverage of weak convection this afternoon, we may have more widespread wind. We had one report of damaging microburst winds yesterday around Eaton and Ault. While we don`t expect that to be anywhere close to widespread, there may be more of that this afternoon. The situation gets a bit more complicated this evening, as moisture will be increasing from the east. The environment on the plains may be more favorable for rain, and if it moistens fast enough there could even be 1000-1500 J/kg of CAPE and an environment supportive of slow moving supercells. It probably won`t moisten up enough to realize the full potential of that, but there`s a better chance of mid to late evening storms with locally heavy rain and hail over the eastern part of the plains. They will still be fighting the warm air aloft though, so it`s hard to tell how long they will hold on. For now, the main change to the forecast was to increase cloud cover, and lower nighttime temperatures in the mountain valleys where we`ve been a little bit too warm the past several nights. && .LONG TERM /Friday through Wednesday/... Issued at 355 AM MDT Thu Jun 13 2024 An upper level trough axis begins to replace an upper level high pressure system Friday morning. Lingering showers crossing from the northeast plains into Kansas are possible early Friday morning. Winds aloft shift southwesterly and cross sections indicate potential low clouds persisting over I-76 until late morning. This would be a limiting factor to the severe weather potential Friday afternoon if these clouds limit our daytime heating. Given PWATs range between 1.00-1.50 inches over the region and QPF fields significantly increasing amongst guidance, scattered to numerous showers and storm will occur by Friday afternoon. There are several favorable factors for storms to become severe along the eastern plains such as MLCAPE nearly 1000-1500 J/kg and lapse rates between 7-8 C/km. Although CAMs are in favor of this severe potential, looking at temperatures, they seem to over estimate how much warming will occur in the afternoon. With higher forecast confidence of cooler temperatures, leaning towards the severe threat occurring north of I-76 for a brief window Friday afternoon. These severe storms could produce wind gusts up to 60 mph and hail. Nonetheless flooding will be the main hazard through Friday evening. Expecting storm motion to move rather slow thus there is a higher flooding threat if storms are able to stall or train over the same area. Across the Divide, the Cameron Peak burn area near Miller Fork could reach minor flooding concerns Friday afternoon. This weekend, 700mb temperatures increase between 15-18C. This pattern will lead to another round of 90s for the urban corridor and plains. Mountains and valleys increase between 67-79. Marginal fire weather conditions could return Sunday due to warm and dry conditions but this will depend on fuel status. Mid-level moisture remains limited leading to isolated chances of a shower or storm mainly for the high country both Saturday and Sunday afternoon. Next week, warm and dry conditions are expected through Tuesday night. && .AVIATION /06Z TAFS through 06Z Friday/... Issued at 1202 AM MDT Thu Jun 13 2024 VFR through Thursday. A weak front will bring a shift to north winds around 14z-16z. Isolated showers and thunderstorms between 22z and 02z will produce areas of gusty winds. A wind shift or two are likely during this time with gusts up to 35 knots. && .HYDROLOGY... Issued at 355 AM MDT Thu Jun 13 2024 Elevated flows continue across the upper Colorado River basin in Grand County, with Flood Advisories in effect for streams above Granby and Grand Lake. Remain alert of the dangers of water that is running high and cold. Flows may increase over the next few days as hot temperatures are expected followed by showers and storms on Friday. On Friday, heavy rainfall will be possible on the plains where PW`s are expected to range between 1.00"-1.50". However, the storms are expected to be slow moving which could increase flooding potential. Moisture levels across the high country will be lower; however, there could be localized areas of heavy rainfall which could cause flooding issues across the burn scars. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Gimmestad LONG TERM...AD AVIATION...Gimmestad HYDROLOGY...AD/Gimmestad