Outlook for the week (monsoon surge for Tue-Thu)

07/20/25 10am: Morning, happy Sunday. I'm having a casual morning at home in Westminster after a nice weekend in the mountains. Lets take a look at what we can expect weather wise this week.

Overall seeing a surge of monsoon moisture combined with a couple short-waves which will bring much better rain and thunderstorm chances across much of the state (mountains and front-range) especially from Tue-Thu this week (with Tue likely being the most active weather day).

Here are some main points

• Hot today with isolated high-based storms for both the central mountains and front-range (Den/Bou) from 2pm-7pm, best chances today will be in the mountains (Summit, Grand counties, etc) and also in the foothills. Not much for Den/Bou

• Moisture increases tomorrow (Monday). On Monday good storm chances from say Summit to ClearCreek / Grand counties south and east including the front-range (Den/Bou) form 1pm-7pm.

• For the front-range on Mon, best chances along/south of I-76 and also in the foothills and Palmer Divide south of Denver (after 3pm will have best chances)

• Models show even deeper moisture that will combine with a short-wave on Tue and that will set the stage for numerous storms on Tue (likely the wettest day this week)

• For the north-central mountains on Tue a good chance for scattered storms 1pm-8pm, best chances from Vail east (including Summit and Grand counties, etc) and especially over the front-range mountains (after 3pm on Tue)

• For Den/Bou and the front-range also good chances for scattered storms on Tue from 3pm-9pm (foothills initially spreading onto plains later).

• We will stick with good afternoon thunderstorm chances on both Wed and Thu especially over the central mountains (north and south central CO, higher terrain will be favored)

• Then it dries out starting Friday and especially into Sat and Sun of next weekend (so drier Fri, Sat and Sun)

  
  

So overall wetter conditions in the mountains Tue-Thu and maybe lasting into Fri we shall see. But really hoping this monsoon surge pans out for the mountains, they need it. Unfortunately I'm not seeing much rain at all this week (or in the next 7-10 days) for western CO: from Steamboat to Glenwood and west towards Grand Junction will remain pretty dry.

First image loop shows forecast Precipitable Water Vapor Anomaly from now through Fri afternoon from latest GFS (we look for those darker greens). Second image shows forecast radar at 4pm tomorrow (Mon) from latest HRRR model. Image 3 shows 24hr precip ending Wed am (for Tue) and fourth image shows forecast total precip from now through next Sat am from latest GFS....take amounts with big grain of salt but shows where strongest signals are for heavy rain this week (central mountains finally).