National Weather Service Forecast Discussion |
Thornton Weather Forecast Today's Forecast Story |
572 FXUS65 KBOU 220855 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 255 AM MDT Wed Jul 22 2026 .KEY MESSAGES... - Storm coverage and intensity increases today and Thursday as monsoonal moisture moves into the region. Storms from today onward will be capable of producing locally heavy rainfall along with a localized threat of flash flooding. - Storm coverage expected to decrease again by Friday into this upcoming weekend, although mountain areas should see at least scattered storm coverage each afternoon and evening. - Temperatures will rise back into the upper 90`s to lower 100`s over northeast Colorado for the weekend into early next week. && .DISCUSSION /Through Tuesday/... Issued at 250 AM MDT Wed Jul 22 2026 For today, will continue to see monsoon moisture moving across the area as the main upper level high is centered to the southeast of the area. PW`s across the high terrain will be from 150% to 200% above normal so expect areas of heavier rainfall during the aftn with the stronger storms. Across the plains, the low level flow will be SSE with a Denver cyclone expected by aftn. Should see tstms develop along the associated convergence zone with storms moving slowly to the east across the plains from late aftn thru the evening hours. Additional storms may also develop along the I-25 Corridor as outflow boundaries move across from the higher terrain. Once again, with PW`s aoa 150% of normal, expect some areas of heavy rainfall. SBCAPE will range from 1500-2000 j/kg over the plains but overall shear will be fairly weak. However, can`t rule out an isold marginal svr storm or two. Highs this aftn, will remain in the upper 80`s to mid 90`s over nern CO. For tonight, a weak upper level trough will move into wrn CO which may allow for showers and a few tstms to continue over the higher terrain overnight. Across the plains, should see a decrease in shower/tstm activity by midnight. On Thu, monsoon moisture will continue over the area as the weak upper level trough moves across the area. PW`s are still fcst to be from 150% to 200% above normal. Thus should see another round of showers and storms across much of the area with areas of heavy rainfall. Highs on Thu will be in the mid 80`s to lower 90`s across the plains. Looking ahead to Fri and Sat, the upper level high will gradually build back into the area as monsoon moisture decreases. As a result, will see tstm activity become more sct over the higher terrain with only a slight chc of storms over the plains both days. Highs will be warmer as well, as readings rise back into the upper 90`s to lower 100`s, across the plains by Sat. For Sun into Mon, an upper level high will extend from the Great Basin across Colorado. The ECMWF and GFS are in better agreement tonight, with regards to whether there will be another surge of monsoon moisture moving into the area. Both models now show monsoon moisture affecting the area both days, especially across the higher terrain. Meanwhile temperatures will remain in the upper 90`s to lower 100`s for highs across nern CO. && .AVIATION /06Z TAFS through 06Z Thursday/... Issued at 1113 PM MDT Tue Jul 21 2026 Outflow boundary frm convection to the north is moving across the area late this evening. Will see a brief period of gusty north winds as this feature moves across. Winds should decrease by 07z and then will gradually shift to south by 10z. On Wed, light and variable winds in the morning will become ENE by 17z. Sct tstms will move across the between 21z and 01z so have included a tempo group. Brief gusty winds up to 40 mph and visibility restrictions from 3-5 miles occur. Naturally if a stronger storm were to occur then may see higher wind gusts with lower visibility. Wind speeds and directions will be chaotic as storms move across. After 01z, should see decreasing potential for tstms so will just mention prob30 for showers thru 06z. Winds will be SSW during the evening hours. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...RPK AVIATION...RPK