Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0351 AM CST Sat Dec 19 2020 Valid 221200Z - 271200Z ...DISCUSSION... Medium-range guidance continues to forecast significant amplification of a shortwave trough moving out of the Pacific Northwest D4/Tuesday. Forecast guidance suggests this shortwave deepens as it moves over the Plains on D5/Wednesday and continues maturing over the eastern CONUS on D6/Thursday. Very strong mid-level flow will develop around this upper trough, with a very deep surface low and strong cold front also anticipated. Main uncertainties are the speed of the system's eastward progression and the quality of the moisture return ahead of the cold front. Current guidance would suggest some low-probability severe potential does exist on D5/Wednesday and D6/Thursday, but limited moisture return is forecast to limit a more widespread severe threat.
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