421 FXUS65 KBOU 132017 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 217 PM MDT Fri Jun 13 2025 .KEY MESSAGES... - A few severe storms possible over the plains late this afternoon and evening. Less coverage and less intense showers/storms (but still gusty winds) over most of the I-25 Corridor and mountains. - Drying trend this weekend with the chance for thunderstorms mostly confined to the northeast plains. - Summer heat this weekend through Monday. Brief respite Tuesday and Wednesday, but then hot again end of next week. && .DISCUSSION /Through Friday/... Issued at 217 PM MDT Fri Jun 13 2025 Water vapor satellite imagery showing drier air has moved over the area and even drier air is upstream for this weekend. For the rest of this afternoon/evening we`ll see high-based showers and thunderstorms form and then progress eastward across the higher terrain and urban corridor. Wind gusts up to 50 mph will be possible with the showers/storms, any rainfall is expected to be short lived. As storms continue eastward, they will encounter an increasingly unstable airmass over eastern Colorado. MLCAPES of 1500-2500 J/kg are more than enough for severe storms with large hail and damaging winds. However, shear won`t be that great with 0-6km bulk shear of 25 to 35 knots. The stronger flow aloft and better shear will be to the north of Colorado. So we don`t expect strong supercell thunderstorms, but the multicellular storms still could produce golf ball sized hail and 70 mph winds. The greatest threat window is 6PM to 10PM and the area will be east of a line from Cheyenne to Fort Morgan to Limon. Upper level ridging centered over the Central and Southern Rockies this weekend, then shifting slightly eastward on Monday. This will result in very warm temperatures all 3 days with highs in the 90s across northeast Colorado. Cross sections show some mid level moisture, which is expected to result in isolated high- based showers. Chances rainfall reaches the ground are low, but gusty winds will likely occur during the mid afternoon to early evening hours each day. Over eastern Colorado, southeast lower level winds will help hold moisture in place. The warm temperatures combined with the moisture will yield 1500-3000 MLCAPE. However with the ridge overhead, mid level temperatures will be warm and flow aloft will be weak, greatly limiting the severe weather threat. However, the far northeast plains will see the strongest flow aloft and have the greatest chance at seeing strong/severe storms each day (Saturday-Monday). On Tuesday, an upper level trough pushes eastward across the Central Rockies Tuesday. This will bring a cold front and cooler temperatures with highs in the 80s across northeast Colorado. This system will also bring a chance for showers and thunderstorms. The ECMWF ensembles generally favor showers and storms, while the GFS ensembles lean on the drier side. Will keep a mention of showers and storms in the forecast for Tuesday. The trough shifts east of the region by Wednesday. Northwest flow behind the trough will bring drier weather back to the region. Temperatures will stay below 90F one more day on Wednesday before the upper level ridge rebuilds over the Central and Southern Rockies. The ridging overhead will bring very warm air back to the area for Thursday and Friday with highs in the 90s across northeast Colorado. The heat continues into next weekend (June 21st & 22nd) with a strong summer ridge over the region or just east of us. Highs are expected to continue to be well into the 90s with a few low 100s possible. && .AVIATION /18Z TAFS through 18Z Saturday/... Issued at 1115 AM MDT Fri Jun 13 2025 VFR conditions are expected through tonight and Saturday. Weak southeast winds to prevail before showers and thunderstorms develop over the higher terrain and push eastward. Main threat with this will be gusty winds to around 35 knots, possibly ~(10% chance) up to around 45 knots near the stronger downdrafts. Chance for a thunderstorm is still around 30% at the DEN airports, but chances for gusty outflow winds and wind shifts are high (greater than 90%). Threat for showers and storms ends 00Z to 01Z as they move off to the east. A typical wind pattern is expected after 00Z Saturday with east to southeast winds (possibly gusty from exiting storms) at first, then turning a typical southerly drainage direction. Like this morning, low clouds will be possible over northeast Colorado, but are expected to stay north and east of the Denver area. For Saturday, winds will generally be light, becoming east to southeast after 18Z. Dry microbursts with wind gusts to 30 knots will be possible from high-based showers after 21Z Saturday. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Meier AVIATION...Meier