Area Forecast Discussion
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
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573 FXUS65 KBOU 271027 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 427 AM MDT Mon May 27 2024 .KEY MESSAGES... - Mostly dry and mild Memorial Day with light winds. Only an isolated late day shower or weak storm over the mountains south of I-70. - Warm through the coming week. There will be limited late day thunderstorm activity on Tuesday with better coverage Wednesday through Friday. A few severe storms are possible on the plains with the highest threat on Wednesday and Thursday. && .SHORT TERM /Through tonight/... Issued at 407 AM MDT Mon May 27 2024 As a ridge continues to build over the western CONUS, today`s holiday forecast for northern Colorado looks to be sunshine filled with light winds and above normal temperatures. There is a slight chance for some isolated, high-based convection to develop over the mountains in the afternoon/evening time frame, mainly for areas south of I-70 where the HREF puts SBCAPE values in the 250 - 500J/kg range. With dry lower levels, chances for measurable precipitation are minimal. Forecast daytime temps are high 70s for the plains with a few locations topping 80, and 60s and 70s for the mountains and foothills. With clear skies expected overnight, temperatures are expected to cool off quickly after sunset resulting in overnight lows dropping a few degrees below normal. Overall, it will be a beautiful day for a Memorial Day celebration! && .LONG TERM /Tuesday through Sunday/... Issued at 407 AM MDT Mon May 27 2024 We`ll settle into a fairly normal early summer weather pattern this week with convective coverage and the threat of any severe storms determined by subtle and hard to predict details. Temperatures will warm Tuesday and Wednesday with light southwest flow aloft and southeast low level winds over the plains. Moisture will increase, but it will struggle to get warm enough for convection on the plains Tuesday. We`ll eventually get some storms, but they may be focused on the terrain especially in the afternoon. There could be enough CAPE on the eastern part of the plains to support strong updrafts, but with questionable heating and not much shear yet, the severe threat still looks pretty low. Wednesday will have stronger low level winds and should be warm enough for a crop of diurnally driven storms. Models have vacillated on the details of the low level flow, but it still seems likely that there will be a dryline east of the cities that could be the focus for a greater severe threat. Mid level winds are still pretty weak though which will likely limit the threat. Thursday had looked like a bigger severe threat with stronger winds aloft and a better chance of advecting moisture westward ahead of the incoming front. But the timing of the front may be too fast, or maybe just slow enough for a more substantial Palmer Divide/east central Colorado severe threat. Both of these days will see the storm threat mainly along and east of the Front Range, with less moisture further west but still enough heating for isolated storms. Guidance temps for these days are similar to the current forecast and look good. There`s been a trend in the models since yesterday for a weaker/more north trough about Friday. We still get a Thursday afternoon/evening cold front, but in most runs the temperature drop is limited to 5 to 10 degrees. These "weaker" solutions could actually be more favorable for thunderstorm coverage and intensity as there really won`t be much change, still some low level moisture, enough instability, and maybe sufficient shear for some threat of severe storms. By Saturday, there`s likely to be some drying aloft, though how much that reduces the surface moisture/instability isn`t clear. The severe threat should be lower, but there could still be a good crop of diurnal storms. Sunday will have additional drying with some warming and a bit less shear. However, these changes might be slight, and a return of southerly winds on the plains could help hang on to some instability. && .AVIATION /06Z TAFS through 06Z Tuesday/... Issued at 1143 PM MDT Sun May 26 2024 VFR conditions through the TAF period. Winds are taking slightly longer to make the turn to southwest than expected, but they are are still expected to remain a WSW component through the overnight hours. Tomorrow will bring northeasterly winds by 14Z - 15Z, and transition to a more easterly component as peak heating persists and the diurnal upslope kicks in between 18Z - 0Z. There is a low probability (10%) that a storm may move south of APA in the evening. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Bonner LONG TERM...Gimmestad AVIATION...Bonner