Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0343 AM CDT Fri Sep 13 2019 Valid 161200Z - 211200Z ...DISCUSSION... The medium-range models generally indicate that a significant short wave impulse will emerge from the base of initially amplified large-scale mid-level troughing, near the Pacific coast at the start of the period. It appears probable that this perturbation will accelerate northeastward across the northern Rockies and Plains, and north of the international border by Wednesday night, accompanied by modest surface cyclogenesis from eastern Montana through the Hudson Bay vicinity. This seems to provide the primary focus for any appreciable severe thunderstorm potential across the U.S. during this period, which could impact areas from the immediate lee of the northern Rockies into the northern Plains Tuesday through Tuesday night, and portions of the Upper Midwest on Wednesday. However, the extent of this potential remains unclear at this time, and may considerably hinge on sub-synoptic developments with low predictability in this extended forecast time frame.
There’s more click here.