Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0347 AM CST Mon Dec 16 2024 Valid 191200Z - 241200Z ...DISCUSSION... Medium range guidance is in fairly good agreement that an amplified but progressive upper level pattern will overspread the CONUS during the Day 4-8 period. A shortwave trough over the northern Plains early on Day 4/Thu will deepen and spread east over the eastern half of the CONUS through Day 6 or 7/Sat or Sun. Meanwhile, an amplified upper ridge will build over the western states and spread east into the Plains during this same time period. Spread among guidance increases around Day 6-8/Sat-Mon, but still indicates that another upper trough will emerge over the Plains and Midwest late in the period. A surface cold front will move south and east into the Gulf of Mexico and offshore the Atlantic coast on Thursday. This will clear out any lingering boundary-layer moisture and persistent offshore trajectories will mostly preclude much thunderstorm potential for most of the forecast period. The exception may be on Day 7-8/Sun-Mon as lee troughing allow for southeasterly flow to return across the western Gulf and TX, bringing modest moisture northward across southern/central TX. Nevertheless, severe-thunderstorm potential appears low throughout the forecast period.