4/20 – Rob Knight’s “Warm, More Humid” Afternoon Forecast
Onshore flow develops this afternoon as elevated winds will bring in the moisture very quickly. Those 2 changes will jump start the upcoming moderating period. We should see about a 5 degree rise in lows and high temperatures today and again on Thursday. Not any warming for Friday, but stays above climatology. From a rain chance perspective, I’m not carrying any in the portion of the forecast period. Subsidence aloft will stunt precipitation probability during the period. Showers may develop just northwest of the area today as a weak disturbance tracks across the upper Mississippi Valley. Will concede that it’s possible that a stray shower or 2 could develop over northwestern portions of the area, but the probability appears to be too low to justify having precip chances in the forecast.
High pressure at the surface and aloft will still keep much of the early part of extended period dry at this time. Rain chances look to hold off for the start of the weekend but could increase during the day on Sunday. The greater chance for rain will be on Monday, late in the period, as a cold front approaches and pushes through late in the day. Temperatures will slowly warm in the extended to just above normal values as the high pressure shifts east.