Area Forecast Discussion
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
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551 FXUS65 KBOU 300251 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 851 PM MDT Wed May 29 2024 .KEY MESSAGES... - Scattered thunderstorms this afternoon and evening. A few severe storms are likely with large hail and strong winds in areas east of I-25 the main threat. - Scattered afternoon showers and thunderstorms Thursday-Friday. A few could be severe across the eastern plains. - Warmer and drier beginning Saturday. Hottest temperatures so far this year likely Sunday into Monday. && .UPDATE... Issued at 849 PM MDT Wed May 29 2024 Storms have mostly weakened and moved out of northeast Colorado with the exception of a line of thunderstorms moving east across southwest ELbert and Lincoln county. An outflow boundary moves westward across the Denver airport and Adams and Arapahoe counties. Made some minor adjustments to the precipitation probabilities to reflect the last of the showers/storms exiting to the east. && .SHORT TERM /Through Thursday/... Issued at 239 PM MDT Wed May 29 2024 Ongoing scattered storms and showers should continue through this evening. Weaker shear, instability, and lower dew points should keep showers non-severe. Areas across the eastern plains to right of the dryline align with SPC slight risk through this evening. Far east, MLCAPE increases near 800-1000 J/kg and lapse rates between 7- 8C/km. There still a lack of favorable shear for thunderstorm development but the threat of hail is high. Up to 2 inch hail could occur from these severe storms along the eastern plains. With cyclone development near DIA and robust outflow boundaries, the threat of landspouts will occur through this evening mainly for Morgan, Washington, Logan, eastern Adams, and eastern Arapahoe counties. Thursday, a cold front will arrive which will lead to lower temperatures in the afternoon. Although conditions should become stable after the front, daytime heating may lead to scattered storms and showers along the Palmer Divide and adjacent plains. There is low confidence in a severe threat of tornadoes but wind gusts up to 60 mph and up to 1 inch hail will likely become the main threat. && .LONG TERM /Thursday night through Wednesday/... Issued at 239 PM MDT Wed May 29 2024 Scattered thunderstorms are expected to continue into the evening Thursday, mainly along and south of I-70. However, the NAM has joined the GFS in showing isolated/scattered storms are able to break the cap across northeast Colorado. Some of these storms are expected to be strong to severe with ML CAPE to around 1000 J/kg. For Friday, westerly flow aloft will increase as a trough passes north of Colorado. Meanwhile at the surface, easterly winds will transport moisture westward with dew points in the upper 40s to lower 50s as far west as I-25. With dew points this high, ML CAPE reaches 1000-1500 J/kg. Seems to be a good setup for strong to severe storms due to good shear, moisture, and instability. One limiting factor to severe storms will be low clouds Friday morning and how long they persist. They could limit warming and result in a capped airmass. Southwest flow aloft will bring warmer and drier conditions to much of the area Saturday. A dry line sets up over the eastern plains Saturday. To the west of it, weak isolated high based showers and storms are expected. To the east of the dry line, strong to severe thunderstorms will again be possible. For Sunday through Wednesday, models continue to advertise a warmer and drier period even though upper level details are somewhat uncertain. For Sunday, a lee side surface trough is expected to develop under a westerly flow aloft. This will bring gusty westerly downslope winds. Temperatures heat up along the Front Range with the first 90 degree day possible. The eastern plains may end up east of the lee side trough. Areas east of the trough will see a chance for afternoon/evening thunderstorms. Monday and Tuesday will remain mild and dry. Downslope flow weakens, which should result in slightly cooler temperatures, though highs are still expected to reach the mid to upper 80s over northeast Colorado. Surprisingly good agreement among the models for Wednesday. They show an upper level trough passing well north of cold. A cold front associated with this system dives south across Colorado Tuesday night bringing cooler and continued dry air for Wednesday. && .AVIATION /00Z TAFS through 00Z Friday/... Issued at 627 PM MDT Wed May 29 2024 The main batch of the remaining showers moves of to the east of the terminals in the next hour. There is lower confidence on what the winds will transition to behind the showers (SW vs SE) at DEN/APA. By mid-evening, winds should begin to settle more southerly at the terminals. The main feature overnight-early Thursday morning will be a weak front that moves southward. The bulk of the front looks to come through in the 11-14z timeframe, but there may be a weak initial "push" of light north winds 08-11z. Winds turn easterly in the afternoon with a chance for scattered thunderstorms after 19z, mainly for DEN/APA. Variable gusts up to 35 kts will likely accompany any passing or nearby storms. Most activity should push out early evening. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Mensch SHORT TERM...AD LONG TERM...Meier AVIATION...Mensch