After a challenging spring for temperatures and precipitation, as we are finally seeing summer like temperatures as we enter July. Two weeks ago I indicated that the GFS model was hinting at a substantial move to warmer conditions as upper air ridging built in from the western U.S.  The latest model runs continue to reinforce that idea through the first half of July.

Meteorologists often use the thickness of the atmosphere between 500 and 1000 millibars (mb) to make temperature forecasts. Using the GFS thickness levels to project temperatures going forward, it appears that the state should experience plenty of days with highs exceeding 90°F through July 11, with several days when temperatures could break the century mark.

Current GFS model runs indicate that widespread 90s should prevail from June 27-31, with upper 90s to low 100s possible across southwestern Nebraska during the June 28-31 period. A brief cool down is projected from July 1-4 as the ridge responsible for this warm-up buckles in response to energy riding along the periphery of the ridge.  This will allow temperatures to cool into the upper 70s to low 80s north to the mid 80s to low 90s south.

The best opportunity for widespread moisture appears to be across the Panhandle during the late afternoon and evening hours July 1-4 as convection develops along the front range of the Rockies. Currently, the GFS doesn’t project widespread precipitation chances across the eastern half of the state.

There appears to be some uncertainty regarding temperatures from July 5-7 as the GFS wants to warm temperatures dramatically back into the upper 80s in the north to near 100°F in southwest Nebraska July 5, cooling back into the mid to upper 80s on July 6, and into the upper 70s to low 80s on July 7.  The GFS depicts another wave moving around the periphery of the upper air ridge and this period would represent the best opportunity for widespread moisture across eastern Nebraska.

Warmer conditions appear to develop once again toward the end of the GFS model forecast period July 8-11. Projected thickness levels point toward high temperatures moving from the mid to upper 80s on July 8 into the mid to upper 90s July 10-11. The GFS indicates that the best potential for 100°F plus high temperatures will be across southwestern Nebraska July 10 and central Nebraska on July 11. 

Although the GFS hints that there may be some widely scattered thunderstorms developing during this period, high temperatures moving into the upper 90s usually signal a stable atmosphere with little chance of precipitation. With crops rapidly growing with our recent uptick in temperatures and projections for warmer temperature to hold through at least mid-July, expect that crop water use will increase dramatically these next two weeks.

In addition, heat indices will be on the rise and cattle stress may become an issue depending on how much air flow is generated on those days when the thermometer approaches the century mark.  The good news is that the forecast is fairly favorable for haying, but pinpointing where occasional scattered convection will develop this far out is a fool’s errand.